site preparation for a deep foundation test site, at

SITE PREPARATION FOR A DEEP FOUNDATION TEST SITE, AT THE

UNIVERSITY OF CENTRAL FLORIDA

By

EVELIO HORTA Jr

A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT

OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF ENGINEERING

UNIVERSITY OF FLORIDA

2003

Copyright 2003

by

Evelio Horta Jr

To my parents.

ACKNOWLEDGMENTS

The writer would like to thank Dr. Frank C. Townsend for being a very patient and

dedicated educator, for providing me with a complete access to his knowledge of

geotechnical engineering, and for serving as committee chair and guiding me through this

research. I would also like to thank Dr. Michael C. McVay and Dr. Paul J. Bullock, for

being my professors and guides throughout my career. A special thank you is offered to

Dr. Brian Andreson for his knowledge of the pressuremeter, computers and his

unconditional help during the development of the research. I am also greatly indebted to

Mr. Chris Kolhoff and Mr. Julian Sandoval for their assistance during this work.

A special thank you is extended to the many friends the writer made during his stay

in Gainesville, the great geotechnical and materials group, to Dr. J. L. Davidson and Dr.

F. T. Najafi, for always treating me as their student and cordially returning my greetings,

to those who give me the opportunity to go back in time, and let me use my student’s

sandals for a second chance, and made it even better, and to the beautiful girls on the

way.

I thank my mother and father, and my family, for their constant support and

sacrifices during my master’s work, for their love.

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TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................................................................................. iv

LIST OF TABLES...............................................................................................................x

LIST OF FIGURES .......................................................................................................... xii

ABSTRACT…………………………………………………………………………….xix

CHAPTER 1 INTRODUCTION ............................................................................................................1

Objectives .....................................................................................................................1 Scope of Work. .............................................................................................................3 Thesis Organization. .....................................................................................................3

2 LITERATURE REVIEW .................................................................................................5

Insitu Testing at FDOT-UCF Site, Literature Reviews ................................................5 Standard Penetration Test (SPT) ..................................................................................5

The Standard Penetration Test...............................................................................5 Test history.....................................................................................................5 Test concept....................................................................................................7 Safety hammer................................................................................................9 Problem statement ........................................................................................10 Approach to the energy measurement ..........................................................11 Energy measurement at FDOT-UCF site. ....................................................12 Data control unit...........................................................................................12

Cone Penetrometer Test (CPT)...................................................................................13 The Cone Penetrometer Test ...............................................................................13 CPT Correlations .................................................................................................15

Cohesionless soil ..........................................................................................15 Cohesive soil ................................................................................................17 The piezocone penetrometer ........................................................................18

Dilatometer Test (DMT).............................................................................................19 The Flat Dilatometer Test....................................................................................19 Penetration Stage .................................................................................................20 Expansion Stage ..................................................................................................21 Intermediate and Common Soil Parameters ........................................................22

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DMT approach to lateral pile loading ..........................................................23 Cohesive soil ................................................................................................23 Cohesionless soils ........................................................................................25

The Pencel Pressuremeter Test (PMT) .......................................................................25 History of the Pressuremeter ...............................................................................25 The Pencel Pressuremeter....................................................................................30

Geophysical Methods .................................................................................................33 Ground Penetrating Radar ...................................................................................33

GPR surveys focus on ..................................................................................34 Earth material properties ..............................................................................36

Electroresistivity..................................................................................................37 Electrical concepts........................................................................................37 Electrical resistivities of selected earth materials.........................................38 Description of the ERI technique .................................................................39

Laboratory Testing......................................................................................................40 The Triaxial Test .................................................................................................40 Soil Classification Based on Grain Size Distribution..........................................41

3 INSITU TEST METHODS.............................................................................................43

Standard Penetration Test (SPT) ................................................................................43 SPT - Dynamic Penetration Test .........................................................................43 Standardized Sampler ..........................................................................................43 Standardized Hammer. ........................................................................................44 Drilling Technique...............................................................................................44 Energy Entering Rods (Not Standardized) ..........................................................45 Factors Affecting Energy, Ei Factors...................................................................46

Cone Penetration Test (CPT)......................................................................................48 Electrical Cone Penetration Proceeding and Standards.......................................48 Device..................................................................................................................48 Types of Cone......................................................................................................48 Test Procedure .....................................................................................................49 Measured Parameters...........................................................................................49 Soil Properties Inferred from the Test .................................................................49

Sands ............................................................................................................49 Clays.............................................................................................................50

Factors Affecting Results ....................................................................................50 Correction for Interpretation................................................................................50 Additional Sensors...............................................................................................50 Data Reduction ....................................................................................................51

Dilatometer Test (DMT).............................................................................................51 Description of Test ..............................................................................................51 DMT Equipment..................................................................................................53 Measured Parameters...........................................................................................54 Factors Affecting Results ....................................................................................54 Available Standard ..............................................................................................55 Corrections for Pressures.....................................................................................55

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Pressuremeter Test (PMT)..........................................................................................57 Device..................................................................................................................57 Test Procedure .....................................................................................................58 Calculated Parameters. ........................................................................................58 Factors Affecting Results ....................................................................................58 Corrections for Pressures.....................................................................................58 Calibration of Equipment ....................................................................................58 Pressure Correction .............................................................................................59 Volume Correction ..............................................................................................59 Probe Insertion.....................................................................................................61 Test Execution .....................................................................................................63 Data Reduction ....................................................................................................64 Hand Solution vs Use of Computer Spreadsheet to Perform Data Reduction ....65

Ground-Penetrating Radar ..........................................................................................67 Test Proceeding ...................................................................................................67 Device..................................................................................................................69 Fieldwork.............................................................................................................69

Electrolresistivity........................................................................................................70 Equipment. Electrical Resistivity Imaging (ERI)................................................70 Soil Properties Directly Measured During Test ..................................................71 Applications of Technique ..................................................................................71 ERI Test Procedure and Data Reduction.............................................................72

Triaxial Testing...........................................................................................................75 Initial Measurements ...........................................................................................75 Fundamental Relationship Equations ..................................................................77 Test Procedure .....................................................................................................78

4 INSITU TESTING FOR SITE CHARACTERIZATION ..............................................80

Insitu Testing ..............................................................................................................80 Presentation of Test Results........................................................................................83

Standard Penetration Test (SPT) .........................................................................83 SPT test location...........................................................................................83 Ground water elevation ................................................................................83 Grain size distribution ..................................................................................84

Standard Penetration Test with Energy Measurements.......................................90 Group east ....................................................................................................90 Group west ...................................................................................................92 Comparison of all SPT data .........................................................................94 N-value correction........................................................................................97

Dilatometer Test (DMT)....................................................................................100 DMT layout ................................................................................................100 Data comparison of DMT tests ..................................................................100 DMT results................................................................................................100

Cone Penetration Test (CPT).............................................................................104 CPT layout..................................................................................................104 Data comparison.........................................................................................104

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CPT results .................................................................................................104 Pencel Presuremeter Test (PMT).......................................................................116

PMT layout.................................................................................................116 Test results..................................................................................................116

GPR Test ...........................................................................................................121 Test scope...................................................................................................121 Test layout ..................................................................................................121 Conclusions ................................................................................................125

Electro Resistivity Test......................................................................................126 Test scope...................................................................................................126 Survey run # 1 ............................................................................................126 Survey run # 3 ............................................................................................129 Conclusions ................................................................................................132

Soil Profile.........................................................................................................132 General soil description..............................................................................132 3D soil characterization..............................................................................133 Conclusions ................................................................................................150

5 EVALUATION OF TRIAXIAL TESTING AND INSITU TEST

CORRELATIONS....................................................................................................151

Introduction...............................................................................................................151 Problem Statement....................................................................................................151 Objectives .................................................................................................................152 Testing Layout ..........................................................................................................152 SPT Correlations.......................................................................................................154 SPT vs. Cohesion......................................................................................................156 CPT and DMT Discussion........................................................................................158

6 PMT TESTING AND CALIBRATION.......................................................................164

Friction Reducer Evaluation .....................................................................................164 Test Comparison (Friction Reducer Ring vs. No Friction Reducer Ring) ...............164

Comparison at Lake Alice .................................................................................164 Characteristics of the site. (cohesive soil) clays.........................................164 PMT test results - Lake Alice location.......................................................167 Data reduction method ...............................................................................170

Comparison at Archer Landfill research site.....................................................173 Characteristics of the site (cohesionless soil) sands...................................173 Test conditions and results from work at Lake Alice location...................174

Conclusions .......................................................................................................179 Analysis of results ......................................................................................179 Suggested future work................................................................................180

7 CONCLUSIONS AND RECOMENDATIONS...........................................................181

Conclusions...............................................................................................................181

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FDOT-UCF Research Site.................................................................................181 Triaxial Testing and Correlations......................................................................182

SPT vs φ angle............................................................................................182 SPT vs cohesion .........................................................................................183 SPT, CPT and DMT vs triaxial testing ......................................................183

PMT Results ......................................................................................................183 Recommendations.....................................................................................................184

APPENDIX A STANDARD PENETRATION TEST (SPT) BORING LOGS ..................................185

B PMT BACK UP DATA FOR LAKE ALICE AND ARCHER LANDFILL...............208

Archer Landfill CPT. ................................................................................................209 Lake Alice CPT. .......................................................................................................211

C BACK UP DATA FPR TRIAXIAL TEST..................................................................213

LIST OF REFERENCES.................................................................................................219

BIOGRAPHICAL SKETCH ...........................................................................................222

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LIST OF TABLES

Table page 2.1. Basic DMT data reduction formulae, for determine soil parameters..........................23

2.2.Values of end bearing factor kp for driven or bored piles ...........................................33

2.3. Electromagnetic properties of earth materials ...........................................................36

2.4. Electrical resistivities of selected earth materials .......................................................39

2.5. Unified Soils Classification System ...........................................................................42

3.1. Some factors in the variability of standard penetration test N-value .........................46

3.2. NSPT suggested by Bowles .........................................................................................47

3.3. Example of proposed calibration method for volume correction curve .....................61

3.4. Typical antenna work performances...........................................................................69

4.1. Summary of testing program and responsible agency ................................................81

4.2. Grain size distribution Bartow SPT 1 .........................................................................85

4.3. Grain size distribution Bartow SPT 2 .........................................................................86

4.4. Grain size distribution Universal SPT 1 .....................................................................87

4.5. Grain size distribution Universal SPT 2 .....................................................................88

4.6. Grain size distribution Nodarse SPT1.........................................................................89

4.7. Uncorrected SPT analyzer data group east .................................................................91

4.8. SPT analyzer data group west.....................................................................................93

4.9. Summary of the uncorrected N-values obtained at the site from 7 SPT.....................95

4.10 Summary of corrected N-values obtain from SPT test where energy measurements were performed.................................................................................98

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5.1. Triaxial test results. SPT 1 “hard” area on site, SPT 2 “soft” area on site ...............157

5.2. General friction angle at UCF sit based on CPT correlations. SPT-2 “soft” area, SPT-1 “hard” area ..................................................................................................158

5.3. Summary of comparison between Triaxial testing , CPT and DMT ........................160

6.1. Comparisons of the Ei modulus obtain from research versus back up data from insitu class 2002 .....................................................................................................170

6.2. Comparison of the pressuremeter initial modulus (Ei) and unload reload modulus (EUR) at Archer Landfill site...................................................................................179

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LIST OF FIGURES

Figure page 1.1. Aerial view showing location of research site, in the vicinity of The University of

Central Florida, Orlando. ...........................................................................................1

2.1. Accuracy or reliability scale for field insitu testing .....................................................6

2.2. Split-spoon sampler used in standard penetration test .................................................7

2.3. Evolution of the SPT hammer to the Safety hammer, or Standardized hammer........10

2.4. Electric force transducers located at the sleeve of the electrical cone probe..............13

2.5. Full assembled (ready for testing) electrical cone penetrometer ................................14

2.6. Proposed correlation between cone bearing and peak friction angle for uncemented quartz sands ..............................................................................................................15

2.7. Relationship between cone bearing and constrained modulus for normally consolidated, uncemented sands ..............................................................................16

2.8. Relationship between cone bearing and drained Young’s modulus for normally consolidated, uncemented sands ..............................................................................16

2.9. Statistical relation between Su/σ’vo ratio and Plasticity Index, for normally consolidated clays. ...................................................................................................18

2.10. Normalized Su/σ’vo ratio and plasticity Index, for normally consolidated clays......18

2.11. Dissembled Dilatometer blade (probe), showing expandable membrane mechanism................................................................................................................20

2.12. Deformation of soil due to wedge penetration..........................................................21

2.13. Kögler’s sausage-shaped pressuremeter ..................................................................26

2.14. A modern version of the Ménard pressuremeter ......................................................27

2.15. Self-boring pressuremeter sold by Cambridge Insitu ...............................................28

2.16. Full displacement pressuremeter, very similar to the CPT probe.............................29

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2.17. The pavement pressuremeter probe .........................................................................30

2.18. Pressuremeter curve with limit pressure and moduli denoted. .................................31

2.19. Curves for the assessment of unit limit friction qs ...................................................33

3.1. Standardize Safety hammer .......................................................................................44

3.2. DMT setup ready for testing.(Schematic shows pressure source, control unit, Dilatometer, pneumatic-electrical cable) .................................................................52

3.3. DMT test method sequence .......................................................................................53

3.4. Dilatometer blade or probe, with dissemble(expandable) membrane ........................53

3.5. DMT control unit ........................................................................................................54

3.6.Calibration of Sensing disc, feeler and quartz cylinder using the tripod dial gauge ...55

3.7. Calibration of the blade before and after the reading of A and B pressures imply obtain the values of ∆A and ∆B. After changing the membrane for a new one, it most be exercise an proceed with several readings to obtain a consistent value of ∆A and ∆B ...............................................................................................................56

3.8. Reading of ∆A and ∆B from unit box ........................................................................56

3.9. The PENCEL pressuremeter probe. Friction reducer ring on tip (figure upper left corner) ......................................................................................................................57

3.10. Methodology for plotting of calibration curve..........................................................61

3.11. Representation of control unit valves, during testing performance ..........................62

3.12. Example of how to correct the raw curve using pressure and volume correction curves .......................................................................................................................64

3.13. Example of the use of spreadsheets to obtain, the correction curves........................65

3.14. PENCEL pressuremeter curve with Limit Pressure and moduli denoted.................66

3.15a. GPR Reflection method, using common offset mode.............................................68

3.15b. GPR reflection method, using common midpoint mode ........................................68

3.16. Schematic illustration of common offset single fold profiling .................................68

3.16. Diagram of a Dipole-Dipole array configuration. Current (A and B) electrode and potential (M and N) electrode locations as survey progress down the transect line

xiii

from left to right. The depth of measurement increases as spacing between electrodes pairs increases .........................................................................................73

3.17. ERI profile of contoured resistivity values beneath survey line using RES2DINV software. Top pictured is measured values; middle picture is calculated values of apparent resistivity; bottom picture is a best-fit model of resistivity .......................73

3.18. Electroresistivity electrode array configurations ......................................................74

3.19. Triaxial cell, height measurement.............................................................................76

3.20. Mohr circles and envelopes ......................................................................................78

4.1. Plan view of the site with the exact location of the tests performed...........................82

4.2. Energy analysis SPT group east..................................................................................91

4.3. Energy analysis SPT group west. Appreciable difference exist between the SPT’s from 8 to 17 feet. Probable cause is due to existence of hardpan layer located at this same depth. Both are mudded holes (Bentonite)......................................................93

4.4. General site stratigraphy from summary of 7 SPT tests. Notice the difference between East and West side due to hardpan layers ..................................................94

4.5. Typical trend of uncorrected N values from 7 SPT at FDOT-UCF site .....................96

4.6. Typical trend of corrected N-values from SPT test where energy measurements were performed .................................................................................................................99

4.7. DMT results for comparison between UF DMT 1 and SMO located at east group of SPT tests .................................................................................................................101

4.8. DMT results for UF DMT 2 and FDOT District 1 located at west Group of SPT tests .................................................................................................................102

4.9. East vs. West comparison of reduced data from DMT.............................................103

4.10. Location of CPT cross sections at the FDOT-UCF site..........................................106

4.11. CPT soundings at NE corner location 1..................................................................107

4.12. CPT soundings at NW corner location 2 ................................................................108

4.13. CPT soundings at SW corner location 3 .................................................................109

4.14. CPT soundings at SW corner location 4 .................................................................110

4.15. CPT soundings at center location 5 ........................................................................111

xiv

4.16. CPT soundings at south location 6 (South-Center) ................................................112

4.17. CPT soundings cross section show increasing tip resistance along SW to SE portion of the site ..............................................................................................113

4.18. CPT soundings show increasing tip resistance along NW to SE cross section of the site ................................................................................................................114

4.19. CPT soundings show increasing tip resistance along SW to NE cross section of the site ................................................................................................................115

4.20. Comparison graph of data interpretation from UF and SMO pressuremeter at depth 5 feet .........................................................................................................117

4.21. Comparison graph of data interpretation from UF and SMO pressuremeter at depth 10 feet .......................................................................................................117





4.26. Comparison graph of data Interpretation from UF and SMO pressuremeter at depth 35 feet .......................................................................................................120

4.27. Test was performed using the Ramac GPR, a 100 mHz antenna, shielded with fiber optics in order to avoid external interference ........................................121

4.28 Location of GPR test at FDOT-UCF research site ..................................................122

4.29. Comparison of the GPR output from pass # 5 with GMS soil profile at same location. Data compared from 0 to 27 feet of depth...............................................123

4.30. Comparison of the GPR output from pass # 10 with GMS soil profile at same location. Data compared from 0 to 30 feet of depth...............................................124

4.31 All Coast Engineering Inc., crew performing the test. Immediate reading of the antenna is sent to the portable computer, giving the operator an opportunity to control velocity of the pass, and direct detection of anomalies in the field ...........125

4.32. Location of electro resistivity surveys (Run) # 1 and 3 at the UCF site.................127

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4.33. Interpretation of soil profile from test Run #1. CPT 5 and SPT Universal 2 were added to figure for visual comparison ...........................................................130

4.34. Interpretation of soil profile from test Run # 3. CPT’s 3, 4, 5 and SPT Universal 2 were added to figure for visual comparison. The interpretation of data equals reduced data from CPT and SPT....................................................131

4.35. Relative location of the CPT, SPT and DMT borings performed at the site ..........135

4.36. Overhead view. Cross section A delineates the borderline between “soft” west area and “hard” east area. Hard Pan layer is located at depths 5 to 12 feet ...136

4.37. 3D view of the site looking toward North, standing at SE corner ..........................137

4.38. 3D View of the site looking towards South standing at NW corner.......................138

4.39. Cross section A is located on the border between “hard” and “soft” layer. Cross section B shows extension of a third layer of silty sand below the clay layer not seen on the general 3D view ..................................................................................139

4.40. Cross section A is located on the border between “hard” and “soft” layer. Cross section E shows the change of soil type from silty sand to sand in the upper layer (this cross section is located between the “hard” SW corner and “soft” NE corner) ..................................................................................................140

4.41. Cross section C is characterizing the “soft” area to the West. Cross section D is characterizing the “hard” East. This is a typical example of the use of the software when designing piles. The information shown provides enough information to determine the extension of a soft layer sensitive to scour..............141

4.42. Cross section characterizing FDOT-UCF site soil profile along the SE to NW edge.................................................................................................................142

4.43.The overlaying hardpan and sand layers have been removed, exposing the steep shape characteristic of uppers layers at the site. Elevation of NW corner is 0 feet, elevation of SE corner is 30 feet...................................................143

4.44. First layer of silty sand has been removed, exposing a second layer of sand below it. Overhead layer at 25 feet ........................................................................144

4.45. SE corner view at depth of 30 feet. The overlying hardpan, and two sand layers have been removed exposing the “silty-sand” layer....................................145

4.46. SE corner view at depth of 45 feet. The overlying hardpan, two sand layers, and “silty-sand” layer have been removed exposing the “clay” layer. Overhead view at depth 33 feet ..............................................................................................146

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4.47. SE corner view at depth of 50 feet. The overlying hardpan, two sand layers, “silty-sand,” and “clay” layers have been removed exposing the medium cemented sand layer. Overhead view at depth of 50 feet.......................................147

4.48. General tip resistance characterization of the site...................................................148

4.49. Comparison showing the change in tip resistance between “Hard” NE corner and “Soft” SW corner.............................................................................................149

5.1. Location of SPT testing for extraction of Shelby tubes............................................153

5.2. Different trends plotted by the use of correlations interpreting N values as Friction Angle (φ) of the soil..................................................................................155

5.3. Best-fit NSPT correlations for triaxial laboratory results ...........................................156

5.4. Most suitable correlations for determine cohesion when compare with triaxial results .....................................................................................................................157

5.5. Friction angle comparison; insitu testing vs. measured (Triaxial) at “Hard” area of site (SPT-1) ........................................................................................................159

5.6. Friction angle comparison; insitu testing vs. measured (Triaxial) at “Soft” area of site (SPT-2) ........................................................................................................159

5.7. Soil profile base on information collected by CPT ,DMT, SPT and Triaxial testing .....................................................................................................................161

5.8. Comparison of insitu testing CPT, DMT, SPT vs. Triaxial testing results in the East side of site.......................................................................................................162

5.9. Comparison of insitu testing CPT, DMT, SPT vs. Triaxial testing results in the West side of site .....................................................................................................163

6.1. Sketch of general soil profile at Lake Alice. Highlighted appear the main clay layer tested on this research. ..................................................................................165

6.2. Sketch of research site at Lake Alice showing relative location of new PMT testing (denoted NR and WR) vs. previous PMT-2. On the sketch also appear location of CPT test used as reference for soil profile ...........................................166

6.3. Lake Alice comparison of different friction reducer at depth 5 feet.........................167

6.4. Lake Alice comparison of different friction reducer at depth 10 feet.......................168



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6.7. Copy of hand reduced data, from pressuremeter test performed by insitu class 2002 at Lake Alice , depth 1,5 m ...........................................................................171

6.8. Copy of hand reduced data, from pressuremeter test performed by insitu class 2002 at Lake Alice , depth 2,5 m ...........................................................................172

6.9. Archer Landfill soil profile based CPT data from previous research .......................173

6.10. Location of research site at Archer landfill.............................................................174

6.11. Archer Landfill comparison of different friction reducer at depth 5 feet ...............175

6.12. Archer Landfill comparison of different friction reducer at depth 10 feet .............175

6.13. Archer Landfill comparison of different friction reducer at depth 20 feet .............176

6.14. Archer Landfill, comparison of all data available at depth 5 feet...........................177

6.15. Archer Landfill, comparison of all data available at depth 10 feet.........................177

6.16. Archer Landfill, comparison of all data available at depth 20 feet.........................178

7.1. FDOT-UCF site soil profile along the SE to NW edge ............................................181

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Abstract of Thesis Presented to the Graduate School

of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Engineering

SITE PRPARATION FOR A DEEP FOUNDATION TEST SITE, AT THE UNIVERSITY OF CENTRAL FLORIDA

By

Evelio Horta Jr

December 2003

Chair: Frank C. Townsend Major Department: Civil and Coastal Engineering

An experimental test site located at the University of Central Florida (UCF),

Orlando, has been selected for evaluating deep foundations. The 300 ft. by 300 ft. test site

has been cleared and fenced. The objective of this site characterization program was to

provide a comprehensive suite of insitu tests for future evaluation of axial and lateral

capacities of deep foundations. The scope of work has been divided into three phases.

The first phase consists of the analysis and comparison of the insitu testing

performed at the site: five instrumented Standard Penetration Tests (SPT), seventeen

Cone Penetration Tests (CPT), four Dilatometer Test (DMT), and two PENCEL

Pressuremeter Tests (PMT) soundings. Inasmuch as the SPT is the most common insitu

test, comparisons were made among (1) drilling operators, (2) hammer type (safety vs.

automatic), and (3) cased vs. drilled mudded holes. Energy measurements were also

conducted to compare the SPT data. Electricoresistivity and GPR tests were added in

order to compare information obtained by the use of geophysical methods of insitu

xix

exploration. From these comparisons the following conclusions were drawn: (1) a general

profile was defined. The generalized soil profile is (1st) 0-5 ft. loose sand, (2nd) 5-33 ft.

sand, silty sand, (3rd) 33-52 ft. silty clay – clayey sand, (4th) 52-60 ft. medium cemented,

gravelly silty sand. (2) The existence of a hard pan sand layer on the center and eastward

side of the site was located between the 8 to 15 ft of depth. (3) Comparisons between SPT

borings using a hollow stem auger vs. a cased hole using an automatic trip hammer

revealed little difference in N values. SPT energy measurements gave energy

measurements of 82% for an automatic hammer, and only 65% for a safety hammer. (4)

Comparisons between DMT and CPT borings using three different agencies revealed

consistent results with little variation between agencies. (5) The geophysical exploration

methods show agreement with rest of the data. (6) PMT measurements between two

different agencies revealed substantial differences.

The second phase of work included the comparison of results from triaxial

laboratory tests with the results of the insitu testing performed. The triaxial test results

back up the interpretation of the information obtained with insitu testing.

The third phase of work involved performing additional comparative testing of the

PMT at previous research sites studied by the University of Florida, and the development

of an explicit methodology for PMT calibration and performing of the test. The

experience accumulated in this testing program led to establishing a new calibration and

testing methodology .The PMT test program was inconclusive in reference to previous

discrepancies at the UCF site and there are still some difference of results, when depths

of testing are greater than 20 ft. A new testing program should be performed to clarify the

discrepancies.

xx

CHAPTER 1 INTRODUCTION

As a result of the continuously increasing use of deep foundation solutions in the

transportation industry throughout Florida, the FDOT decided to create a full scale testing

research site to evaluate deep foundation designs. The experimental site is located at the

University of Central Florida (UCF), Orlando, close to the university campus as shown in

Figure 1.1 The test site occupies an area of 300 ft. by 300 ft. and has been cleared and

fenced in order to maintain the area.

Objectives

The first objective proposed by the investigation committee organized by the

FDOT was to obtain proper site characterization. A program was established to provide a

comprehensive suite of insitu tests for future evaluation of axial and lateral capacities of

deep foundations.

In order to obtain a good spectrum or variability on the results, different research

agencies and institutions were selected randomly, in order to represent Florida’s

geotechnical consulting companies. Due to the accumulated experience on this type of

work, the University of Florida was chosen as the entity in charge of the compilation,

reduction and presentation of the data in a report format.

1

N

2

Figure 1.1. Aerial view showing location of research site, in the vicinity of The University of Central Florida, Orlando.

3

Scope of Work.

The scope of work has been divided in three phases.

The first phase consists of the analysis and comparison of the results obtained from

the insitu testing performed at the site: seven instrumented SPT, seventeen CPT, four

DMT, and two PMT soundings. ER & GPR tests were added in order to compare

information obtained by the use of advanced geophysical methods of insitu exploration.

The main propose is to develop an accurate soil profile, based on a summary of the

different interpretations provided by each set of tests. Another objective of the

investigation was:

• To determine how much difference would be introduced in the interpretation of the data based on energy variation, between agencies (drillers, operators), variation of equipment or technology.

• Comparison of results from different methods of exploration.

• Agreement of results between geophysical exploration methods and traditional insitu tests.

The second phase of work involved the comparison of results from triaxial

laboratory test with the results of the insitu testing performed.

The third phase of work involved performing additional comparative testing of the

PMT at previous research sites studied by the University of Florida, and the development

of an explicit methodology for PMT calibration and performance of the test. A program

of testing to develop solutions in reference to the discrepancies between data results at the

research site was established

Thesis Organization.

Chapter 2 embodies all the literature review relevant to the insitu testing performed

at the site.

4

Chapter 3 presents a brief approach to the standards or methodologies established

in order to perform each test. New recommendations for the performance of the PMT test

are given.

Chapter 4 compiles the presentation of the reduced data from each insitu test

performed at the site. An overall, general soil profile is defined with the compilation of

all the insitu data.

Chapter 5 establishes a comparison of the soil properties classification, between

results from triaxial testing and interpretation of tests based on insitu correlations.

Chapter 6 focuses on the comparison of the results, from a series of testing

programs performed at University of Florida research sites, in order to determine the

reason for differences in performance of the pressuremeter probes.

Chapter 7 provides conclusions and recommendations given by the author.

CHAPTER 2 LITERATURE REVIEW

Insitu Testing at FDOT-UCF Site, Literature Reviews

The FDOT-UCF site is to be used for evaluating deep foundations, so the objective

of the site characterization program was to provide a comprehensive suite of insitu testing

for future evaluation of axial and lateral capacities of deep foundations.

The scope of work to accomplish this program was to perform conventional insitu

tests, i.e. SPT, CPT, DMT, and PMT. Laboratory testing was implemented as well as the

use of geophysical methods of exploration i.e. GPR and Electroresistivity.

The following is an explanation of the history and characteristics of the equipment

used. For the case of the PMT, the author gives new recommendations. Figure 2.1

presents the “accuracy” of insitu testing method for perspective.

Standard Penetration Test (SPT)

The Standard Penetration Test

This test is probably the most widely used field test in the United States. It has the

advantages of simplicity, the availability of a wide variety of correlations for its data

interpretation , and the fact that a sample for visual classification is obtainable with each

test.

Test history

• 1902 C.R Gow, used a 1” diameter sampling tube driven with a 110 lb weight. Prior to this time samples were recovered from wash water.

5

6

Figure 2.1. Accuracy or reliability scale for field insitu testing (Handy , 1980)

7

• 1927 L. Hart and G.A. Fletcher devised the 2” diameter spilt spoon sampler. Same time Fletcher and H.A Mohr standardized the test using the spilt spoon sampler and hammer with a mass of 140 lb dropped from 30” height.

• Terzaghi and Peck incorporate the test and correlations in their book, “Soil Mechanics in Engineering Practice” in 1948.

• Use of the test grew rapidly; today is the common tool for the geotechnical engineer.

Test concept

A standard split barrel sampler is advanced into the soil by dropping a 140-pound

(63.5-kilogram) safety or automatic hammer on the drill rod from a height of 30 inches

(760 mm). The sampler is advanced a total of 18 inches (450 mm). The number of blows

required to advance the sampler for each of three consecutive 6-inch (150 mm)

increments is recorded. The sum of the number of blows for the second and third

increments is called the, N-value (blows per foot {300 mm}). Tests shall be performed in

accordance with ASTM D 1586. Figure 2.2 shows a cross section of the split-spoon

sampler used in the standard penetration test.

Figure 2.2. Split-spoon sampler used in standard penetration test (Bowles 1996)

During design, the N-values may need to be corrected for overburden pressure and

measured (or estimated) hammer energy.

8

Many correlations exist relating the corrected N-values to relative density, angle of

internal friction, shear strength, and other parameters. Some of the most common

correlations used for the SPT data interpretation are shown in Appendix D. Due to the

popularity of the SPT many design methods use N-values directly (uncorrected) in the

design of driven piles, embankments, spread footings and drilled shafts.

But the SPT values should not be used indiscriminately. They are affected by

fluctuations in both individual drilling practices and equipment. Studies have also

indicated that the N-values are more consistent in sands than clays. The SPT penetrates

most soils and some rock, but laboratory test and other insitu tests provide more specific

soil properties with better accuracy, particularly when dealing with clays. The type of

hammer (safety or automatic) should be noted on the boring logs, since this may

significantly affect the actual input driving energy. Bowles (1996) suggested the

following corrections when dealing with safety hammers:

N70 = η* CN * N

where: η represents several efficiency factors and CN is defined by Liao and

Withman (1986) as2/1

'76.95

=

oN P

C

CN corrects the value N value to standard overburden stress. The other η factors

correct the N-values for differences in testing procedure (hammer energy, use of lines,

oversize boreholes and rod length). Details of the corrections for the N-value are

presented in Chapter 3. Appendix D provides a compilation of several correlations

commonly used to estimate soil properties from SPT blowcount.

9

The FDOT uses the two most common types of hammer, the safety hammer with

cathead and rope mechanism and the automatic trip hammer system. Therefore, only

these two systems were tested under the scope of this project and are discussed in the

Chapter 4.

Safety hammer

The safety hammer, shown in Figure 2.3, is one of the two most common hammers

used in the United States because of its internal striking ram that greatly reduces the risk

of injuries. When the hammer is lifted to the prescribed height, the outer barrel and the

enclosed hammer move together as one piece. When released, the hammer falls, striking

the internal anvil and creating an energy wave. The kinetic energy of the system, is

transmitted as a compression wave through the anvil to the center rod. Because the center

rod is threaded into the drill rod string, the wave is then transmitted through the drill rod

string and into the sampler.

The mechanism used to lift the safety hammer is the cathead and rope system. A

rope is tied to the outer barrel of the safety hammer and strung through a pulley, or crown

sheave, them wrapped 2-3 times around a rotating cathead. The free end of the rope is

held by the operator. To conduct the test, the operator pulls the rope to raise the hammer

and then “throws” the rope quickly to release the tension holding the hammer at the 30-

inch drop height, thereby causing the hammer to fall. The raising and dropping of the

hammer is conducted repeatedly until the sampler penetrates the required depth of 18

inches.

10

Figure 2.3. Evolution of the SPT hammer to the Safety hammer, or Standardized hammer

(Bowles,1996)

Problem statement

Unfortunately the ASTM standard (ASTM D1586) allows a wide diversity of

equipment for performing standard penetration testing. As a consequence there are a

variety of hammer types in use, ranging from donut and safety hammers using cathead

and rope systems to the latest in automatic trip hammers. Different hammers introduce

different amounts of energy per blow into the rods and different N-values result. The

ratio of energy provided by the best automatic trip hammer and a cathead system in

which the winch is spooled by the weight of the hammer can be a factor of 4 to 5.

11

Approach to the energy measurement

Since Schmertmann (1979) shoed that the hammer energy is approximately

inversely proportional to the blowcount, this factor dramatically affects any interpreted

soil properties In the early studies of the SPT energy, Kovacs and his co-workers (1981)

used a light scanner and reflection technique to measure the height of hammer fall and

the velocity just before impact. These measurements allowed them to calculate the

potential energy of the hammer drop and the kinetic energy of the hammer just before

impact. They found that the hammer energy just before impact was always less than the

potential energy of the hammer drop due to energy losses. They also found an inverse

linear relationship between SPT N value and hammer energy impact,(N ∞ 1/E) and

proposed that a “standard energy” be established in order to calibrate or adjusting the

hammer fall height to deliver that “standard energy.“

Schmertmann and Palacios (1979) incorporated hollow-center, strain gauge load

cells near the top and bottom of the drill rods to measure the force-time history of the

stress waves. The force data were used to calculate energy transferred into the rods and

energy lost in the sampling process. They found that a drill rod string, less than about 45’

long, limited the hammer-rod contact time and reduce the hammer energy entering the

rods.

Based on these investigations, in order to reduce the variability caused by energy

differences, it is recommended that the SPT N-value be standardized to a particular

energy level, e.g., 60% of the theoretically available energy of 4200 in-lbs. The corrected

N-value would be equal to the N-value obtained, multiplied by the ratio of that rig’s

energy input to the standard 60% energy of 2520 in-lbs.

12

Energy measurement at FDOT-UCF site.

For this test site, equipment for performing the energy calibration was suppliedy by

PDI. The test was perform by GRL & Associates, Inc., on the consulting rigs (Universal

& Nodarse). GRL also helped FDOT personnel perform measurements on the Bartow rig.

Because non-uniformity of cross-section causes force/velocity disproportionality, it

is theoretically better to conduct the test using an instrumented rod of the same size as the

drill string.

The PDI equipment has two type of sensors are used for the rod instrumentation:

• Foil strain gages (350 ohm) glued directly onto the rod in a full Wheatstone bridge configuration to measure strain, which is converted to force using the cross-sectional area and modulus of elasticity of the rod.

• Piezoresistive accelerometers, which are bolted to the instrumented rod. The acceleration measured by these sensors is integrated to obtain velocity, which is used in the Fv computations.

Data control unit.

The data control unit, has a LCD touch-screen for entering rod area and length,

descriptions and names, and user comments. The programmed screens allow for easy data

control and review. The force and velocity traces are continuously displayed during

testing and saved at a user-selected blow frequency in the memory of the unit. The

memory holds the data from approximately 175 blows. The raw data and energy-related

quantities are stored in the memory until downloaded into a computer using the SPTPC

software. After analyzing the data using SPTPC, data plots can be made using PDIPLOT

Version 1.1.

13

Cone Penetrometer Test (CPT)

The Cone Penetrometer Test

The Cone Penetrometer Test is a quasi-static penetration test in which a cylindrical

rod with a conical point is advanced through the soil at a constant rate and the resistance

to penetration is measured. A series of tests performed at varying depths at one location is

commonly called a sounding.

Several types of penetrometers are in use, including mechanical (mantle) cone,

mechanical friction-cone, electric cone, electric friction-cone, and piezocone

penetrometers. Cone penetrometers measure the resistance to penetration at the tip of the

penetrometer, or the end-bearing component of resistance. Friction-cone penetrometers

also include a friction sleeve, which provides the added capability of measuring the side

friction component of resistance. Mechanical penetrometers have telescoping tips to

allow use of an inner rod to minimize rod friction and generally provide measurements at

intervals of 8 inches (200 mm) or less. Electric penetrometers, like the one shown in

Figure 2.4 and Figure 2.5, use electric force transducers, to obtain continuous

measurements with depth. Piezocone penetrometers are also capable of measuring pore

water pressures during penetration.

Figure 2.4. Electric force transducers located at the sleeve of the electrical cone probe

14

For all types of penetrometers, cone dimensions of a 60-degree tip angle and a 1.55

in2 (10 cm2) projected end area are standard. The friction sleeve outside diameter is the

same as the base of the cone. Penetration rates should be between 0.4 to 0.8 in/sec (10 and

20 mm/sec). Tests shall be performed in accordance with ASTM D 3441 (which includes

mechanical cones) and ASTM D 5778 (which includes piezocones).

Figure 2.5. Full assembled (ready for testing) electrical cone penetrometer

The penetrometer data are plotted showing the end-bearing resistance, the friction

resistance and the friction ratio (friction resistance divided by end bearing resistance) as

functions of depth. Pore pressures, if measured, are also plotted with depth. The results

should also be presented in tabular form indicating the interpreted results of the raw data.

The friction ratio plot can be analyzed to determine soil type. Many correlations of the

CPT test results to other soil parameters are available, as direct design methods for spread

footings and piles. The penetrometer can be used in sands or clays, but not in rock or

strong dense soils. The CPT not provide a soil sample, so penetrometer exploration

should always be augmented by SPT borings or other borings.

15

CPT Correlations

Cohesionless soil

Relative density: Dr (Jamiolkowski 1985)

[ ] 5.010 'log6698

vo

cr

qD

σ+−=

Friction angle φ: using Figure 2.6 (design using CPT, by Campanella,1995)

Figure 2.6. Proposed correlation between cone bearing and peak friction angle for

uncemented quartz sands, (Campanella 1995)

Tangent modulus Mt: using Figure 2.7 (Campanella, 1995)

cv

t qm

M α==1 , 113 −=α

16

Figure 2.7. Relationship between cone bearing and constrained modulus for normally

consolidated, uncemented sands (Campanella, 1995).

Secant modulus; using Figure 2.8 from Campanella (1995)

cqE α=25 , 35.1 −=α

Figure 2.8. Relationship between cone bearing and drained Young’s modulus for

normally consolidated, uncemented sands (Campanella, 1995).

17

Dynamic shear modulus: Gmax (Imai and Tonouchi, 1982)

611.0max 125NG = , 5.4=

Nqc

Cohesive soil

Undrained shear strength: Su

k

cu N

qS 0σ−

= , 15=kN

Sensitivity: St (Campanella)

(%)f

st R

NS = , 6=Ns

Stress history OCR; using Campanella procedure, Guidelines for Geotechnical

design using CPT, (Campanella, 1995)

• Estimate Su from qc or ∆u

• Estimate vertical effective stress, σ’vo from soil profile.

• Compute Su/σ’vo

• Estimate the average normally consolidated (Su/σ’vo) NC for the soil-using Figure 2.9. Knowledge of the plasticity index (PI) is required.

• Estimate OCR from correlations by Ladd and Foott (1974) and normalized by Schmertmann (1978) and reproduced in Figure 2.10.

If the PI of the deposit is not available, Schmertmann (1978) suggests assuming an

average (Su/σ’vo) NC ratio of 0.33 for most post-pleistocene clays.

18

Figure 2.9. Statistical relation between Su/σ’vo ratio and Plasticity Index, for normally

consolidated clays.

Figure 2.10. Normalized Su/σ’vo ratio and plasticity Index, for normally consolidated

clays

The piezocone penetrometer

The piezocone penetrometer can also be used to measure the dissipation rate of the

excessive pore water pressure. This type of test is useful for soils, such as fibrous peat or

muck, which are very sensitive to sampling techniques. The cone should be equipped

19

with a pressure transducer that is capable of measuring the induced water pressure. To

perform this test, the cone is advanced into the soil at a standard rate of 0.8 inch/sec (20

mm/sec). Pore water pressures are measured during penetration and during dissipation

intervals, when penetration stopped. The recorded data are then used to plot a pore

pressure versus log-time graph. Analysis of the dissipation rate providespermeability and

consolidation parameters.

Dilatometer Test (DMT)

The Flat Dilatometer Test

The Flat Dilatometer Test (DMT) is a simple, repeatable and economic insitu

penetration test. The small size of the dilatometer blade enables data to be collected close

to the foundation surface where the lateral response of piles is most influenced. The

(DMT) shown in Figure 2.11, was developed in Italy by Marchetti in the late 70’s. The

Dilatometer probe consists of a stainless steel blade with a thin flat circular expandable

steel membrane on one side. When at rest, the external surface of the membrane is flush

with the surrounding flat surface of the blade. The blade is pushed into the ground using a

penetrometer rig or a drilling rig. The blade is connected to a control unit on the surface

by a nylon tube containing an electrical wire. The tube runs through the penetrometer

rods. At 20-cm depth intervals jacking is stopped and, without delay, the membrane is

inflated by means of pressurized gas. Readings are taken of the A-pressure required to

just begin to move the membrane and of the B-pressure required to move its center 1.10

mm into the soil. The rate of pressure increase is set so that the expansion occurs in 15

sec—30 sec. Also the thickness of the blade (15 mm) was chosen as small as possible

consistent with the requirement that it must not be easily damaged or bent. The maximum

20

deflection, 1.10 mm, was chosen as small as possible in order to keep soil strains in the

expansion stage as small as possible.

Figure 2.11. Dissembled Dilatometer blade (probe), showing expandable membrane

mechanism

The DMT is best used in soils, which are finer than gravelly sands. It is not

recommended in soils which have penetration obstructions such as rock layers,

concretions, cobbles, cemented zones, large shells (bouldery glacial sediments or gravelly

deposits). These soils resist penetration and may damage the blade and the membrane.

Penetration Stage

The dilatometer causes a wedge bearing failure during a essentially plane-strain

penetration. A possible way of analyzing the penetration process is to model it as the

expansion of a flat cavity, where the measured horizontal total soil pressure against the

blade increases with the horizontal insitu stress, soil strength parameters, and soil

stiffness.

The penetration of the dilatometer causes a horizontal displacement of the soil

elements originally on the vertical axis of 7.5 mm (half thickness of the dilatometer),

displacement considerably lower than that induced by currently used conical tips [18mm

for cone penetration test (CPT)]. which, according to a theoretical solution by Baligh

(Research Report, MIT No517), shows the different strains caused by wedges having an

apex angle of 20° (angle of the dilatometer) and 60° (angle of many conical tips), may

21

give an idea of the different magnitudes of the strains induced by DMT and CPT. Figure

2.12 gives a graphical explanation to previous statement.

Figure 2.12. Deformation of soil due to wedge penetration (Baligh, MIT No 517)

Because of the nearly plane-strain penetration, shear and volume strains adjacent to

the membrane are nearly uniform and relatively small. Much less than a smilar size

axisymetric penetration.

Expansion Stage

In this stage the increments of strain in the soil are relatively small. The theory of

elasticity may be used to infer a modulus. This modulus relates primarily to the volume

of soil facing the membrane. However this soil has been prestrained during the

penetration. As already noted, shear strains in this volume are low (compared with the

22

strains induced by other presently used penetrating devices, such as the cone

pressuremeter).

However soil stiffness is sensitive to prestrain. Thus empirical correction factors

are necessary to evaluate the stiffness of the original soil.

The A and B pressure readings, (taken from the dilatometer control unit), are

corrected using the calibrations ∆A and ∆B, determined by measuring the membrane

stiffness in air. Test and calibrations procedures are discussed at the Chapter_3.

Intermediate and Common Soil Parameters

The corrected A-pressure, Po and B-pressure, Pl are key values used to determine

the “intermediate” DMT parameters, the material index ID, the horizontal stress index KD

and the dilatometer modulus ED. The original correlations (Marchetti 1980) were

obtained by calibrating these parameters versus high quality measured soil properties.

The values of insitu equilibrium pore pressure uo and of the vertical effective stress σ’vo,

prior to the insertion of the probe, must be estimated also.

Table 2.1 shows the reduction formulae needed to determine the common soil

parameters for which the DMT provides an interpretation. The constrained modulus M

and the undrained shear strength Su (in Table 2.1 as Cu) are believed to be the most

reliable and useful parameters obtained by DMT (Marchetti, 2001).

23

Table 2.1. Basic DMT data reduction formulae, for determine soil parameters. (Marchetti et al., 2001)

DMT approach to lateral pile loading

Because the dilatometer blade displaces soil laterally during penetration it may also

be used to model the lateral stress against a driven pile. However the DMT induce

relatively small strains and empirical correlations are required to estimated lateral pile

load-deflection response.

In contrast, pressuremeter methods, induce larger lateral strains and have the

advantage that the cylindrical expansion can be considered a more reasonable direct

model of the lateral movement of the soil during lateral loading of piles (Robertson

P.K,1984).

Cohesive soil

In cohesive soil, the lateral deflection yc is a function of the undrained strength of

the soil, the insitu effective stress level and the soil stiffness.) The value of the pile

24

deflection yc based on a concept proposed by Skempton (1951) (as appears in Robertson

et al.,1989) that combines elasticity theory, ultimate strength method and laboratory soil

properties. Based on his work and the experience gained by University of British

Columbia and different authors yc is determine by the following equation.

DCc EF

DSuy⋅

⋅⋅=

5.067.23

where

Su and ED are calculated with the empirical correlations (Table 2.1).

D= diameter of the pile in cm

FC = 10 (as first approximation for cohesive soil).

For clays, the evaluation of the ultimate static lateral resistance Pu is given by

Matlock and Reese (1960) as

DSNP upu ⋅⋅=

where

Su is calculated with the empirical correlations (Table 2.1).

D= diameter of the pile

Np= Non dimensional ultimate resistance coefficient 9

Near the surface, because the lower confining stress level, the value of Np is

calculated by

++=

DxJ

SN

u

vop

'3

σ

where

σ’vo = effective vertical stress at x

x = depth

25

J = empirical coefficient 0.25 –0.5

Cohesionless soils

The ultimate lateral soil resistance Pu is determined from the lesser value given by

the following two equations:

( )[ ]βφσ tan'tan' ⋅⋅+−= papvou kxkkDP

[ ]apopvou kkkkDP −++= 'tan'tan2' 23 φφσ

where

φ’ = Angle of internal friction.

ka = Rankine active coefficient

kp = Rankine passive coefficient

ko = Coefficent of earth pressure at rest

β = 45° + φ/2

For the prediction of lateral pile response on sands, yc is calculated as

( ) DFE

ySD

voc 'sin1

''sin17.4φ

σφ−⋅

=

The method outlined above does not address the pile group effect, or the effect of

cycling loadings. Respective corrections must be applied for these effects.

The Pencel Pressuremeter Test (PMT)

History of the Pressuremeter

Kögler, a German, developed the first pressuremeter and used it to determine soil

properties somewhere around 1930. His pressuremeter was a single cell, long, and

hollow device, which he inserted into a bore hole and inflated with gas. The results of

26

this early pressuremeter were often difficult to interpret, and its development was

hampered by technological difficulties (Baguelin et al., 1978). Figure 2.13 shows

Kögler’s pressuremeter.

Figure 2.13. Kögler’s sausage-shaped pressuremeter (Baguelin et al., 1978)

Louis Ménard, developed the modern soil pressuremeter in 1954 working on his

university final year project. Also a prebored PMT This apparatus was a tri-cell design

with two gas-filled guard cells and a central water-filled measuring cell. Ménard

continued his work under Peck at the University of Illinois for his Master’s thesis, “An

Apparatus for Measuring the Strength of Soils in Place.” By 1957, Ménard had opened

the Center d’Etudes Ménard where he produced pressuremeters for practicing engineers.

Figure 2.14 shows a modern Ménard Pressuremeter marketed by Roctest, Inc.

27

Figure 2.14. A modern version of the Ménard pressuremeter http://www.roctest.com/

roctelemac/product/product/g-am_menard.html)

Although the pressuremeter seemed a radical departure from traditional

geotechnical tests, there were inherent problems with the device. Many believed that the

stresses induced or reduced by drilling the borehole were significant. These stresses were

further complicated by the general quality of drilling. If the holes were too large, the

pressuremeter would possibly not inflate enough to develop a full pressuremeter curve.

On the other hand, if the holes were too small, the insertion of the probe would disturb

the borehole and therefore diminish the quality of the test data.

In an attempt to rectify these drilling issues, engineers at the Saint Brieuc

Laboratory of the Ponts et Chaussées (LPC) in France developed the first self-boring

pressuremeter. As the name implies, this pressuremeter inserts itself into the borehole as

the borehole is being drilled. The premise behind the new device was to prevent

movement of the borehole wall after drilling, and therefore minimize any changes in

stress. A similar device was developed at Cambridge and is sold by Cambridge Insitu

called the Camkometer (Figure 2.15). Data from this pressuremeter proved to be signifi

different from that of the Ménard. While the self-boring pressuremeter may have seemed

28

to be the panacea to PMT problems, it suffered from more of its own. These new probes

were extremely complex and required a great deal of experience and maintenance to

operate.

Figure 2.15. Self-boring pressuremeter sold by Cambridge Insitu (http://www

.cambridge-insitu.com/csbp_leaflet2.htm)

Reid et al.,(1982) and Fyffe et al.,(1985) address the pre-boring affects by

developing a push-in type of pressuremeter. This new probe was developed primarily for

use in the characterization of soils for offshore drilling structures. This new

pressuremeter is hollow much like a Shelby tube. Soil is displaced into the probe during

pushing, thus eliminating the cutting system. Unfortunately, the probe has to be extracted

after every test to clean out the displaced soil.

A more recent development in pressuremeter technology is the full displacement or

cone pressuremeter. This probe is pushed, as a cone penetration test, and then inflated as

a traditional pressuremeter. This method eliminates the problems associated with drilling

29

and the complexity of the self-boring equipment. Full displacement probes have been

researched at the University of British Columbia, the University of Ottawa, and Oxford

University. A commercially available full displacement type of pressuremeter is shown

in Figure 2.16.

Figure 2.16. Full displacement pressuremeter, very similar to the CPT

probe.(http/www.Cambrige–Insitu.com/specs/Insttruments/CPM:html

The first cone pressuremeter probe was developed by Briaud and Shields (1979).

Their pressuremeter was developed primarily for the pavement industry to test the

granular base and sub base layers and cohesive and granular sub grades.

30

Figure 2.17. The pavement pressuremeter probe (Briaud and Shields, 1979)

The pavement pressuremeter was developed as a rugged, inexpensive, portable

apparatus for the direct evaluation of the deformation characteristics of the pavement and

subgrade layers. A traditional Ménard type of probe could not be used in the case of

pavement design. The magnitude of the loads and depths of influence due to traffic

loading are very different from those of a shallow foundation. Since the depth of

influence was much smaller, a cone penetration test tip sized monocellular probe with a

singular hydraulic tubing was used. The shortened length of the probe facilitated a

reasonable amount of measurements within the relatively shallow zone of influence.

Strain control was chosen to allow for better definition of the elastic portion of the curve

since stiffness is the important measurement. Additionally, strain control also simplified

the equipment and facilitated cyclic testing.

The Pencel Pressuremeter

The testing device used in this study was the PENCEL model pressuremeter. This

is more or less the commercial version of the pavement pressuremeter developed by

31

Briaud and Shields (1979). An outer sheath of steel strips protects the inner rubber

membrane. Roctest, Inc. manufactures the unit in Canada and markets it worldwide.

As with other pressuremeters, the parameters determined are the Limit Pressure

(PL) and Pressuremeter Modulus (EPMT). The PENCEL limit pressure is defined as the

pressure required to double the cavity volume, or more simply the maximum pressure

during the test. On the other hand, the modulus could come from many portions of the

pressuremeter curve. Due to probe insertion, the initial modulus, Ei, may not be that

reliable. Other portions of the PENCEL curve that could be used for calculating stiffness

are an unload-reload loop, if available, and the final unload portion of the test. These

moduli are referred to as EUR and EUL, respectively. Figure 2.18 shows these moduli and

the Limit Pressure on an arbitrary pressuremeter test.

Ei

EUR

EUL

PL

Figure 2.18. Pressuremeter curve with limit pressure and moduli denoted.

Calculation of the PENCEL Pressuremeter modulus is identical to the Ménard

method:

−

−

+++=

of

offocPMT VV

ppVVVE

2)1(2 µ

32

where

µ is Poisson’s Ratio

Vc is the initial volume of the pressuremeter

Vo and po are the first point on the linear portion of the pressuremeter curve

Vf and pf are the final points on the linear portion of the pressuremeter curve

Practice has shown that the standard pressuremeter test provides reasonable

estimates of bearing capacity and settlement of shallow foundation. Comparisons of

predictions with actual performances have shown that measured, long-term settlements

are in most cases within ± 50% of the predicted values, and often within ± 30%

(Baguelin, Jézéquel, Shields, 1978). The design of bearing capacity of piles under axial

loading based on the pressuremeter method (Menard, 1963) requires the knowledge of an

end-bearing factor, Kp and the unit limit frictions, qsi, in all layers. Then the limit load QL

is

SLPLL QQQ +=

with:

( )[ ]oolPpPL qppKAQ +−= the limit tip load

∑ ×=i sisiSL qAQ the limit shaft friction load

where

PL= the limit pressure from the pressuremeter test

po = the horizontal ground pressure, before the test (roughly estimated from at rest

coefficient ko)

qo = The initial vertical pressure at the foundation level.

33

Readjusted design factors Kp and qs have been proposed for isolated piles by

Bustamante and Gianeselli (1981)(as seen at Robertson et al, 1984) from the examination

of numerous full-scale static loading test results, and are presented in Table 2.2 and

Figure 2.19.

Table 2.2.Values of end bearing factor kp for driven or bored piles (Robertson et al, 1984) Type of Pile

Type of soil Bored Driven Clay or Silt 1.2 - 1.4 1.8 - 2.2 Sand or gravel 1.0 - 1.2 3.2 - 4.2 Chalk, marl or calcareous marl1.8 2.4 - 2.8 Weathered Rock 1.0 - 1.8 1.8 - 2.8

Figure 2.19. Curves for the assessment of unit limit friction qs (Robertson et al, 1984)

Geophysical Methods

Ground Penetrating Radar

Ground-penetrating radar (GPR) uses a high-frequency (80 to 1,000 KHz)

Electromagnetic (EM) pulse transmitted from a radar antenna to probe the earth. The

transmitted radar pulses are reflected from various interfaces within the ground and are

monitored by a radar receiver. Reflecting interfaces may be soil horizons, the

groundwater surface, soil/rock interfaces, cavities, boulders, man-made objects, or any

34

other interface possessing a contrast in dielectric properties. The dielectric properties of

materials correlate with many of the mechanical and geologic parameters of materials.

Generally, the radar signal is transmitted by an antenna in close proximity to the

ground. The reflected signals can be detected by the transmitting antenna or by a second,

separate receiving antenna. The received signals are processed (digitized) and displayed

on a monitor or graphic recorder. As the antenna (or antenna pair) is moved along the

surface, the graphic recorder displays results in a cross-section record or radar image of

the earth. As GPR has short wavelengths in most earth materials, resolution of interfaces

and discrete objects is very good. However, the attenuation of the signals in earth

materials is high and depths of penetration are often limited to less than 10 m. Water and

clay soils increase the attenuation, decreasing penetration. Depths are interpreted by

measuring the tow-way travel tme of the radar pulse and dividing by an assumed

transmission velocity.

GPR surveys focus on

1. Mapping near-surface interfaces.

2. The location of objects such as tanks, utility cables, or pipes in the subsurface.

3. Groundwater depth location.

4. Identification of Subsurface anomalies (cavities, boulders, clay puckets)

Dielectric properties of materials are not measured directly. The method is most

useful for detecting changes in the geometry of subsurface interfaces.

The following questions are important considerations in advance of a GPR survey.

5. What is the target depth? Though target detection has been reported under unusually favorable circumstances at depths of 100 m or more, a careful feasibility evaluation is necessary if the investigation depths exceed 10 m.

6. What is the target geometry? Size, orientation, and composition are important.

35

7. What are the electrical properties of the target? As with all geophysical methods, a contrast in physical properties must be present. Dielectric constant and electrical conductivity are the important parameters. Conductivity is most likely to be known or easily estimated.

8. What are the electrical properties of the host material? Both the electrical properties and homogeneity of the host must be evaluated. Attenuation of the signal is dependent on the electrical properties and on the number of minor interfaces which will scatter the signal.

9. Are there any possible interfering effects? Radio frequency transmitters, extensive metal structures (including cars) and power poles are probable interfering effects for GPR.(mostly eliminated when using a shield antenna)

10. Electromagnetic wave propagation. There are two physical parameters of materials which are important in wave propagation at GPR frequencies.

• One property is conductivity (σ), the inverse of electrical resistivity (ρ). The

relationships of earth material properties to conductivity, measured in mS/rn (1/1,000 Qm), are given in Table 2.3.

• The other physical property of importance at GPR frequencies is the dielectric constant (ε), which is dimensionless. Materials made up of polar molecules, such as water, have a high ε. Physically, a great deal of the energy in an EM field is consumed in interaction with the molecules of water or other polarizable materials. Thus waves propagating through such a material both go slower and are subject to more attenuation. To complicate matters, water, of course, plays a large role in determining the conductivity (resistivity) of earth materials.

36

Earth material properties

Two subsurface materials, cause important variations in the EM response in a GPR

survey, water and clay. At GPR frequencies, the polar nature of the water molecule

causes it to contribute disproportionately to the displacement currents which dominate the

current flow at GPR frequencies. Thus, if significant amounts of water are present, the ε

will be high and the velocity of propagation of the electromagnetic wave will be lowered.

Clay materials with their trapped ions behave similarly. Additionally, many clay minerals

also retain water.

The physical parameters in Table 2.3 are typical for the characterization of earth

materials. The range for each parameter is large; thus the application of these parameters

for field use is not elementary.

Table 2.3. Electromagnetic properties of earth materials (US Army 1995)

Simplified equations for attenuation and velocity (at low loss) are

2/1

8103ε×

=V

2/1

69.1ε

σ=a

37

where

V = velocity in m/s

ε = dielectric constant (dimensionless)

a = attenuation in decibels/m (db/m)

σ = electrical conductivity in mS/m

The large variations in velocity and especially attenuation, are the causes of success

(target detection) and failure (insufficient penetration) for surveys in apparently similar

geologic settings. As exhaustive catalogs of the properties of specific earth materials are

not readily available, most GPR work is based on trial and error and empirical findings.

Electroresistivity

The use of an Earth Resistivity Meter is one of the options in the study of shallow

depth earth exploration, pollution monitoring and archaeological problems. The test

consists on setting several electrodes over a straight measured line in the field, spaced to

a desire length. A current is passed through the electrodes and the voltage drop is

measured between electrodes. A value of resistivity is calculated knowing the current, the

voltage difference and the electrode spacing. The electricity is conducted through the

ground by the electrolytic conductivity of the soil or rock pore fluid and to a lesser degree

by electronic conductivity of metallic solid particles. For the present study performed at

FDOT-UCF site an electrical resistivity imaging (ERI) geophysical method was used.

Electrical concepts

The resistivity of a material is a measure of how difficult it is to make an electrical

current flow through the material, and is measured in Ohm-meters.

38

The overall resistance resulting from every possible flow path is the apparent

resistivity, it is a weighted average of the measured resistivity. If the ground is

homogeneous, the apparent resistivity theoretically equals the true resistivity.

The conductivity of a material is a measure of how easy it is to make an electrical

current flow through the material and is measured in Siemens or mho and usually

expressed in milliS/meter or millimhos/meter. Conductivity is the reciprocal of

Resistivity in terms of propagation of an electrical signal through a medium or material.

Properties which affect the resistivity of soils and rocks:

• Porosity; shape, size, and connection of pore spaces.

• Moisture content.

• Dissolved electrolytes, minerals, or contaminants/pollutants.

• Temperature of pore water. Conductivity of minerals.

Electrical resistivities of selected earth materials

The resistivity of earth materials varies widely for any one material and between

different materials. Various ranges are cited in the geological literature (Table 2.4). The

variation is due largely to differences in moisture content and the salinity of the ground

water (pore fluid) rather than to the minerals themselves. Subsurface Evaluations, Inc.,of

Tampa, Fl, recommends using the resistivity values presented by Vogelsang (1995), as

they seem to represent more accurately the conditions commonly encountered in Florida.

39

Table 2.4. Electrical resistivities of selected earth materials

Description of the ERI technique

Electrical resistivity imaging (ERI) is an advanced geophysical method and is a

much more powerful way of documenting the lateral extent of subsurface layers than old-

fashioned resistivity soundings or profiling. In an ERI survey, typically, 28 or 56

electrodes are placed in the ground in a straight line and are connected by a switching

cable. The electrodes are spaced evenly, usually at distances of 5 to 20 feet, which

corresponds, approximately, to the resolution. A computer is used to switch power on and

off, usually to groups of four electrodes so that every geometrically possible combination

of electrodes is used to collect measurements. Typically, 138 to 281 data points are

measured per transect depending on the type of electrode array. The depth of testing is

about one-half of the length of the line, but the depth of reliable modeling is about 15-

25% of the transect length. Depth of scanning is commonly greater than 100 feet. Usually

about four or five ERI transects can be measured per day.

Measured apparent resistivity values represent weighted averages for the ground

around each group of electrodes. By themselves, they do not show a cross-section of the

ground. To get a useful image, the measured values are downloaded to a computer and

processed using a program, in this case the RES2DINV. This program estimates the true

40

resistivity values at points along a finite-element grid, beneath the survey line, using a

least-squares method. The true resistivity values are modeled through an iterative process

that approaches a unique solution for the subsurface resistivity. There is no guessing

about layer thickness, number of layers or average resistivity of the layers. The model’s

girdded values are contoured to produce a cross section of the subsurface resistivity.

Goodness of fit for the model is automatically calculated as root mean square error.

Laboratory Testing

The Triaxial Test

In the triaxial test a cylindrical specimen of soil is sealed in a watertight rubber

membrane and enclosed in a cell in which it can be subjected to a confining pressure. A

load applied axially through a ram acting on the top cap is used to control the deviator

stress. Under these conditions the axial stress is the major principal stress σ1; the

intermediate and minor principal stresses (σ2 and σ3) are both equal to the cell pressure.

Connections to the ends of the sample permit either the drainage of water and air

from the voids of the soil or, alternatively, the measurement of pore pressure under the

conditions of no drainage.

Generally the application of the confining pressure and the deviatoric stress form

two separate stages of the test; tests are therefore classified according to the condition of

drainage obtained during each stage as

1. Undrained Test( U/U or Q): No drainage and hence no dissipation of pore pressure, is permitted during the application of the all round stress. No drainage is allowed during the application of deviator stress. Used during the end of construction phase of testing.

2. Consolidated-Undrained Test (C/U or R): This method combines a CD test with a UU test. Drainage is permitted during the application of the all round stress, so that the sample is fully consolidated under the pressure. No drainage is allowed during the application of deviator stress. Used primarily to obtain effective stress

41

parameters of impermeable soils. It is used for rapid draw down analyses or means to determine the effective conditions via measured pore water pressure.

3. Drained Test (C/D or S): Drainage is permitted throughout the test, so that the full consolidation occurs under the all round stress and no excess pore pressure is set up during the application of the deviator stress. Used for sands or partially saturated soils.

Fundamental to performing a laboratory triaxial test is understanding the

calculations required for data reduction in determining the pore water pressure during

undrained loading (undrained strength), deformations during drained loading (including

volume change), c and φ values of the soil sample and the effect of stress path leading to

the failure on these values.

Soil Classification Based on Grain Size Distribution

A inexpensive alternative to the triaxial testing is the use of visual categorization

and sieve analysis of samples. This is less expensive and faster than compare with the

triaxial test.

As the visual criteria is extremely dependent on the experience of the technician,

the use of the sieve analysis is more recommendable. There are several authors and

regulations that classified the soil type based on his particle size distribution. For the

present work the Unified Soils Classification Systems was used. The system is shown in

Table 2.5.

42

Table 2.5. Unified Soils Classification System (ASTM D2487) (USAWES,1967)

CHAPTER 3 INSITU TEST METHODS


SPT - Dynamic Penetration Test

The purpose of the test is to obtain a representative soil sample and dynamic

penetration resistance designated as the N value. Blow count is recorded 3 times, each

150 mm (6”) of penetration. The N value is the sum of the blow count of the last 300 mm

(1’) of penetration and is recorded as blows per foot.

The test uses several standards in order to control the performing and improve data

results.

• ASTM D 1586 Penetration Test and Split-Barrel Sampling of Soils

• ASTM D 4633 Stress Wave Energy Measurement of Dynamic Penetrometer Testing Systems (currently withdrawn)

• ASTM D 6066 Determining the Normalized Penetration Resistance Testing of Sands for Evaluation of Liquefaction Potential (N60)

Standardized Sampler

A sample is taken at bottom of a borehole using a “Split-spoon” sampler with

standard dimensions. The sampler may be opened for sample removal. The sampler is

robust enough for penetration, but the samples are highly disturbed and samples are only

suitable for Atterberg Limits, grain size and visual classification.

43

44

Standardized Hammer.

The sampler is driven 18” with a 140 lb (63.5 kg) hammer and a 30” drop. Types of

hammer vary, but the safety hammer is the most common. New automatic hammers

(chain drive or hydraulic piston) have been implemented for use.

Figure 3.1. Standardize Safety hammer (Bowles, 1996)

Drilling Technique

A “clean and stable” borehole, 2.2”-6.5” diameter, must be prepared by:

• Washed boring give poor results • Open-hole rotary drill • Continuous flight hollow stem auger • Continuous flight solid stem auger • Drill mud and casing is the best solution when drilling above GWT

45

However, the following borehole methods are not permitted:

• Jetting through sampler • Bottom discharge bits • Continuous sampling • Drill fluid level below GWT • Casing below test depth

Sample Interval:

Commonly samples are taken every 5 ft (every 2.5 ft better). Samples are visually

classified and transported in small glass jars (ziploc bags now common).

The test is the primary investigation tool, and is used in all but the softest soils. The

sampler can even be driven into layers of rock. It is the most common field test used (&

abused) today. It is excellent for modeling of pile driving and also gives good

information about seismic response.

Energy Entering Rods (Not Standardized)

Inasmuch as hammers, and operators vary, the energy input is greatly affected by

equipment and operator.

E* = maximum theoretical energy = 140 lbs x 30” = 4200 in-lb

Ei = actual energy input varies greatly, historical average about 50-60% of E*

N-value may vary ±100% due to Ei variability see Table 3.1 (from Schmertmann,

1978).

Eri = ratio of actual energy o maximum theoretical energy (%) (Ei/E*)

46

Table 3.1. Some factors in the variability of standard penetration test N-value (Bowles 1996)

Factors Affecting Energy, Ei Factors

• Rope and cathead condition

• Driller condition

• Weather (wind, rain, temperature)

• Hammer & sampler (shoe, wear conditions)

• Loose rod connections

In summary when an engineer performs an interpretation of data from SPT

correlations the following concepts should be keep on mind, in order to evaluate the

effects on the values by energy losses.

• N-value is approximately inversely proportional to Ei.

• N-value results are highly suspect without energy measurements. Each change in personnel or equipment requires another calibration.

• Short Rod Length: tension wave from the sampler cuts off hammer impact, reduces Ei

47

• Automatic Hammer improves precision, but Ei = 70-100% and still requires calibration

• Measure Ei with accelerometer and load cell in the rod string. Then correct N-value.

There are several expressions by different authors in order to correct the NSPT

value. The correction for N-value shown in Table 3.2 is suggested by Bowles (1996). The

blow count N70 is corrected to Eri = 70% corrected to σ’v = 1 tsf (=95.76 kPa), using an

overburden correction to characterize the soil deposit.

Table 3.2. NSPT suggested by Bowles (1996)

48

Cone Penetration Test (CPT)

Electrical Cone Penetration Proceeding and Standards

Among the vast number of in-situ devices, the electrical cone penetrometer (CPT)

represents one of the most versatile tools currently available for soil exploration. The

very first electric cone penetrometer was probably developed at Degebo in Berlin during

the Second World War.

The test procedure is standardized in ASTM D5778. The following items require

attention for proper CPT testing.

• Calibration of load cell and strain gages

• Check for damage or wear of cone tip/sleeve

• Clean rods

• Check the straightness of cone rods with inclinometer

• Ensure the computer runs properly by running test program.

Device

• Cone

• Friction sleeve

• Pore pressure transducer (for piezocone)

• Other sensors (if any)

• Rods

• Control/ measuring device

Types of Cone

Mechanical cone

Electric cone

49

Test Procedure

Test is carried out by mechanically or hydraulically pushing a cone into the ground

at a constant speed (2 cm/s) whilst measuring the tip and shear force. Measurements of

the resistance to penetration of the cone probe are taken by the strain gages located at the

probe and signals are transmitted to the ground surface every 5 cm. Measurements of the

resistance to penetration of the cone and outer surface of a friction sleeve are also

recorded. The first reading on the tip is defined as cone resistance, qc. The second reading

along the body of the probe is the sleeve friction, fs.

For the piezocone, test pore pressure is measured along depth of penetration and a

dissipation test can be performed at any required depth by stopping the penetration and

measuring the decay of pore water pressure with time. It is recommended that the

dissipation be continued to at least a 50% degree of dissipation.

Measured Parameters

• Tip resistance, qc (kg/cm2)

• Friction resistance, fs (kg/cm2)

• Pore pressure, u (for piezocone)

Soil Properties Inferred from the Test

Sands

• relative density, Dr

• friction angle, φ

• Young Modulus, E

• Shear modulus, Gs

50

Clays

• Undrained shear strength, Su

• Sensitivity, St

• Stress history, OCR

Factors Affecting Results

• Type and consistency or density of soils

• Confining pressure or overburden pressure

• Verticality

• Rate of penetration

• Calibration of sensors

• Wear of the cone

• Temperature changes

• A rigid pore pressure measuring system and a fully saturated system (for piezocone)

• Rate of dissipation of pore pressures (for piezocone)

• Location of the filter and axial load on the cone (for piezocone)

• Variations in the test apparatus

Correction for Interpretation

Three major area of cone design that influence interpretation are:

• Unequal area effects

• Piezometer location, size and saturation

• Accuracy of measurement

Additional Sensors

In recent years, the CPT or CPTU has been supplemented by additional sensors,

such-as geophone arrays (seismic cone), lateral stress sensing, a pressuremeter module

51

behind cone-penetrometer, electrical resistivity or conductivity for estimating insitu

porosity or density and, it has also been used as an indicator of soil contamination, heat

flow measurement, radioisotope measurement, acoustic noise, and other geo-

environmental devices.

Data Reduction

The data reduction is based on the use of the guide-lines and software developed

for the use of CPT interpretation, at University of British Columbia, Vancouver, Canada

by R. G. Campanella. The correlations used for this propose are shown in the Chapter 2

Literature Review.

4. The cone “Cleanup” program is used to adjust the bad data points.

5. The “Coneplot” program is used to draw the soil and soil classification chart. The program also calculates an equivalent NSPT value.

6. In order to calculate other soil property correlations, the soil profile is divided into cohesionless and cohesive soil profile, based on the soil classification chart with appropriate range of tip resistance and friction ratio.

Dilatometer Test (DMT).

Description of Test

The test consists of inserting into the soil a stainless steel blade device, having a

flat, circular steel membrane mounted flush on one side. The steel membrane is

expandable and put into action by pneumatic pressure. The blade is connected to a

control unit on the surface by a pneumatic-electrical tube running through the insertion

rods. The pressure to expand or deflation the steel membrane is supply by a gas tank and

controlled on the console by audio visual signal, gauges and vents.

52

Figure 3.2. DMT setup ready for testing.(Schematic shows pressure source, control unit,

Dilatometer, pneumatic-electrical cable)(ASTM draft 6635)

The Dilatometer blade is advanced into the ground by a push rig or a drill rig at

speed between 10mm/s and 30 mm/s while measuring the penetration resistance. Soon

after penetration, by use of the console, the operator inflates the membrane and takes two

readings:

• The A-pressure, required to initiate movement of the membrane against the soil.

• The B-pressure required to move the center of the membrane 1.10 mm against the soil.

The pressurization sequence is controlled by the operator keeping attention to the

audiovisual signals on the control unit

• The buzzer sound and led signal are ON when the membrane rests against the sensing disc. (prior to membrane expansion).

• The signals turn OFF as the membrane expands away from the blade.

• The signals turn ON again when the center of the membrane has moved 1.1 mm into the soil.

53

This process is repeated, after pushing the blade along the desired studied depth

and taking readings of A and B every 20 cm. The A and B pressure readings are corrected

using calibration ∆A and ∆B determined by expanding the membrane in air.

Figure 3.3. DMT test method sequence (ASTM draft 6635)

DMT Equipment

Blade with a stainless-steel membrane mounted on one side of the blade

Rods

Control/measuring unit

Pressure source

Figure 3.4. Dilatometer blade or probe, with dissemble(expandable) membrane

54

Figure 3.5. DMT control unit

Measured Parameters

• P0 = corrected pressure on the membrane before lift-off (i.e. at 0.00 mm)

• P1 = corrected membrane pressure at 1.10 mm expansion

• P2 = corrected pressure at which the membrane just returns to its support after expansion.

• KD = horizontal stress index (a normalized lateral stress)

• ID = material index (a normalized modulus which varies with soil type)

• U0 = pore pressure index (a measure of the pore pressure set up by membrane expansion)

• E0 = dilatometer modulus (an estimate of elastic Young’s modulus)


• Disturbance due to blade insertion

• Blade thickness

• Type of soils

• Membrane stiffness Equipment Calibration

55

Available Standard

Reference on:

Schmertmann (1986)

ASTM Draft, 2001.

Eurocode 7 1997 (see Marchetti and co-workers 2001)

Corrections for Pressures

Calibration of the unrestrained membrane should take place at ground surface

before and after each DMT sounding. Two values of pressure are measured

• The gauge pressure necessary to suck the membrane back against its support

• The gauge pressure necessary to move it outward to the 1.10 mm position

The most important issue will be the correct measurment of ∆A and ∆B since these

values are used to correct the values of A and B.

Figure 3.6.Calibration of Sensing disc, feeler and quartz cylinder using the tripod dial

gauge

56

Figure 3.7. Calibration of the blade before and after the reading of A and B pressures

imply obtain the values of ∆A and ∆B. After changing the membrane for a new one, it most be exercise an proceed with several readings to obtain a consistent value of ∆A and ∆B

Figure 3.8. Reading of ∆A and ∆B from unit box

7. If ∆A and ∆B vary more than 25 KPa during a sounding, the results, according to the Eurocode 7(see Marchetti and co-workers 2001) should be discarded.

8. If the soil is considered to be stiff, the results are not substantially influenced by ∆A and ∆B and using typical values of ∆A and ∆B generally leads to acceptable results.

9. If when checking calibration, the values of ∆A and ∆B didn’t coupe the tolerance of Eurocode 7 for going off scale (∆A= 5 to 30 Kpa, and for ∆B = 5 to 80 Kpa). The operator must dismantle the blade and follow instructions for replacement and calibration of the dilatometer blade and control unit, in order to perform new calibration.

57

Such investigations are beyond the scope of this work. The focus herein is on data

results from the DMT. For more information on this mater the author recommends to the

reader to observe the instructions supplied in “The ISSMGE” report, (Marchetti and co-

workers 2001).

The proceeding of calibration is also recommended before a long period without

using the blade or for installing a new membrane.

Pressuremeter Test (PMT)

Device

• Probe: The testing device used in this study was the PENCEL model pressuremeter. This is more or less the commercial version of the pavement presurememeter developed by Biraud and Shields (1979). Roctest, Inc. manufactures the unit in Canada and markets it worldwide.

• Control / measuring unit: The UF control unit has been modernized. By adding to the system a digital pressure gauge, which reads the changing values of pressure in PSI. This change helps the operator to read more precise values during test performance.

• Tubing / cabling.

Figure 3.9. The PENCEL pressuremeter probe. Friction reducer ring on tip (figure upper

left corner)

58

Test Procedure

The test is carried out by directly pushing the probe into the ground. Horizontal

pressure is applied to the soil at the selected elevation by gradually inflating the probe

until it reaches the capacity of the device. Applied pressure readings are recorded as

increments on volume are applied, thus obtaining a relationship between the radial

applied pressure and the resulting soil deformation.

Calculated Parameters.

EPMT = a pressuremeter modulus

Su = Undrained shear strength

σho = Insitu horizontal stress in the ground


• Type of soils

• The rate of expansion to assure drained or undrained test condition.

• Membrane stiffness and system compliance.

• Disturbance of soil during penetration.

Corrections for Pressures

• The resistance of the probe itself to expansion

• The expansion of the tubes connecting the probe with the pressure-volumeter

• Hydrostatic effects.

Calibration of Equipment

No ASTM standard exists for the PENCEL Pressuremeter test. Instead, the test and

calibration methods are based on the information given on the manual published by

Briaud and Shields (1979). The following is a compilation of the information provided by

the Standard Pencel Pressuremeter (CPMT) Instruction Manual, and our own experience

59

acquired performing these tests. New key elements must be added to the manual and

followed in order to improve the life span of key components of the equipment, and a

better calibration curve during the process of data reduction.

There are two corrections to be applied to the field data:

• Pressure calibration. This determines the pressure correction necessary to nullify the inertia of the sheath. Inertia of the sheath is defined as the required pressure to dilate the probe to a specific volume when the probe is confined only by atmospheric pressure.

• Volume correction. This determines the volume correction caused by the parasitic expansion in the control system and in the tubing and probe. Such difference corresponds to that between the injected volume read in the meter and the real increase in volume of the probe.

Pressure Correction

10. The entire system has to be completely saturated. See Filling and Saturating The Control Unit on ROCTEST manual for Cone PMT. The probe is placed vertically at ground level next to the apparatus. Place valves 3 and 4 in the “Test” position and inflate and deflate the probe five times by injecting 90cm³. This is done to exercise the membrane.

11. The probe is then inflated 90cm³ at an injection speed of about 1/3 cm³/second, which is equivalent to 1 crank turn in 9 seconds. The pressures are recorded for each step of 5 cm³ injected.

12. The pressures that have been recorded are then corrected by taking into consideration the head of water between the pressure gauge and the center of the probe; the inertia curve is the plot of the corrected pressure versus the injected volume.

13. The inertia curve is required for interpretation of the test data and must be established for each new sheath mounted on a probe.

Volume Correction

14. Saturate the entire system including the control unit, the tubing and the probe. Place valves 3 and 4 on “Test” position. Place the probe in a calibration tube. The calibration tube can be any thick wall metal tube with an inside diameter of about 34mm.

15. The manual recommends inflating the probe (in the tube) by injecting water at a rate of 1/3 cm³/sec in increments of 5cm³. Record the pressure for each increment

60

of 5cm³ injected. Continue with the same injection rate and keep record of the pressure at 5cm³ intervals up to 2000 kPa. However:

• This procedure will provide a plot with just a few points for drawing the curve. To facilitate the plotting of this curve with more readings, we recommend recording values of volume based upon pressure once the gauge reached 250 kPa. The additional readings should be performed at pressure values of 2.5, 5, 10 15, and 20 kPa x 100. See example of readings at Table 3.3. These data are used to plot curve A or Control unit + tubing + Probe, shown at Figure 3.10.

16. Deflate the probe by bringing the volume counter back to zero

17. Disconnect the probe from the tubing

18. Progressively increase the pressure in the cylinder and in the tubing up to 2500 kPa, recording the pressure corresponding to each cm³ injected. This data is used to plot curve B or Control unit + tubing, shown in Figure 3.10.

19. Bring back the volume counter to zero.

20. Using readings obtained during steps 2 and 5, trace curves A and B,

• Trace a tangent to curve A, line C - D. • Add a horizontal line from C to E • Measure E – F • Set off distance E – F from point D to find a new point call G • Sketch a curve G – C • Transfer curve G – C – A to origin of graph and obtain the Volume Correction

Curve, C as shown in Figure 3.10. 21. The probe can be connected to the tubing and the test may begin.

The calibration process must be applied again after finishing the test, and if the

tubing or the probe sheaths are changed. Otherwise, calibrations should be repeated for

each new job site or at regular intervals during a large test campaign.

61

Table 3.3. Example of proposed calibration method for volume correction curve

cc Kpa x 100 PSI/30sec0 05 1

10 2.615 4.820 9.225 22.8

27.3 2.5 34.230.4 5 61.933.9 10 126.636.1 15 193.337.8 20 259.437 15 200.5

35.6 10 13533.2 5 66.230.8 2.5 35.325 9.520 4.315 2.110 15 -0 -

Volume Correction

.1

0.31.2

Figure 3.10. Methodology for plotting of calibration curve (Roctest Manual)

Probe Insertion.

The PENCEL probe is designed for insertion by pushing or light hammering. The

probe is inserted saturated and sealed and it may develop internal pressure during

penetration During the process of pushing the pressuremeter with a ram, special attention

62

must be given to the readings on the ram pressure gauge as well on the unit pressure

gauge. These are indicators of potentially damaging stresses acting on the pressuremeter

sheath. The operator should avoid abrupt changes of internal pressure during penetration,

the values of the change in pressure may vary from – 12 psi to 20 psi during insertion on

stiff soils. Values exceeding 20 psi are likely to damage the sheath. The ram pressure

should be kept below 1000 psi. A usual advancing rate on sands and clays should be 500–

600 PSI. The pressure at the beginning of the test should be positive and turn to negative

after finishing test, (rotated handle to the deflate position). The correct position of

actuators or valves for the control unit during performing of the test is shown in Figure

3.11.

Figure 3.11. Representation of control unit valves, during testing performance

The tubing, connecting control unit with probe, has a elative small inside diameter

and a short waiting period may be required for fluid to flow from the membrane back into

63

the control unit at the end of each test and during pressure spikes during penetration. Do

not attempt to retrieve probe from the hole, same conditions apply up or down directions.

After finishing each test, a good way to avoid, damage to the sheath after deflating

the membrane, is to wait for the recommended recuperation or suction period of 7 to 10

minutes. Before continuing with penetration to a new testing depth, advance the probe

slowly one foot into the undisturbed soil below. This action will help to squeeze water

out of the probe reducing its excess volume and minimizing potential damage.

Test Execution

Once the probe has been pushed to the desired test depth and valves # 3 and 4 are

in TEST position, the testing can then be carried out in increments of equal volumes. The

increment of increasing volume is 5 cm3 and the corresponding pressure is noted 30

seconds after having injected the 5 cm3. The maximum volume injected is 90 cm3. A

constant speed of injection should be maintained. Recommended speed is 1/3 cm3/s

which is equivalent to 1 crank revolution in 9 seconds.

When the test is completed, prior to either removing the probe from the hole or

advancing it to a lower level, the probe must be deflated by returning the water to the

cylinder. Under no conditions should setting of the valves # 3 and 4 be changed from the

‘TEST” position, as the PENCEL does not have a release valve to deflate the probe, and

the action of reversing the handle into the deflate position until volume counter reads

0000, is similar to the handling of a syringe, where the action is activating vacuum

pressure on the system. If any of the valves are changed from test position, this will

divert the suction on the system to the water container and will introduce more water in

the circuit, inflating the probe. Probe inflation usually results in membrane destruction

while advancing or retraction the probe.

64

Data Reduction

The analysis of the pressuremeter data begins with the corrections for the volume

and pressure. This is done merely by plotting the volume and pressure calibration curves

obtained during pressure and volume calibration on a graph, following the procedure

described in the previous section and adjusting a new curve, the Volume Correction

Curve. See Figure 3.10. The first step to the interpretation will be to plot the raw

pressuremeter curve (pressure vs. volume). For each point on the raw curve there

corresponds a point on the corrected curve with coordinates of corrected pressure and

corrected volume. The corrected point is obtained by subtracting the volume correction

and the pressure correction from the raw pressure and volume data. The corrected

pressure should also include the hydrostatic pressure.

Volume corrected = Volume read – Volume Calibration

Pressure Corrected = Pressure read – Pressure Calibration + P Hydrostatic.

Figure 3.12. Example of how to correct the raw curve using pressure and volume

correction curves. (Roctest Manual)

65

Hand Solution vs Use of Computer Spreadsheet to Perform Data Reduction

The entire process of plotting the correction and raw curves, in order to obtain the

soil properties and Pressuremeter Modulus from the PMT, has two divergent

methodologies. One of the methodologies requires the reduction of the data entirely by

using a hand procedure, drawing the correction and raw data curves using French curves.

The other method uses of a combination of hand plotting and computer programs or

spreadsheets.

The hand method is more precise than the use of computers due to the fact that

computers cannot obtain a single mathematical equation that fits the shape of calibration

curves loading and reloading. Several approaches have been attempted by UF grad

students, and consist of fitting several curves for each section of the correction curves.

This methodology is closer to the hand proceeding. See example on Figure 3.13 pressure

correction curve.

Figure 3.13. Example of the use of spreadsheets to obtain, the correction curves

(Anderson 2001)

Hand reduction of data results in a tedious and time-consuming effort for everyday

work. For this reason, Dr. Brian Anderson has developed calculation sheets that approach

this problem by trying to introduce the minimum possible error using computer generated

best fit curves.

66

Once the corrected Pressure vs. Volume curve is plotted, two parameters inherent

to the pressuremeter could be obtained. The values of limit pressure and pressuremeter

modulus are obtained from the graph.

The PENCEL Limit Pressure is defined as the pressure required to double the probe

volume, or more simply the maximum pressure during the test. On the other hand, the

modulus could come from many portions of the curve. These moduli are referred to as

initial modulus Ei, unload reload modulus EUR, and unload modulus EUL. Figure 3.14

shows these moduli and the limit pressure on an arbitrary pressuremeter test.

Ei

EUR

EUL

PL

Figure 3.14. PENCEL pressuremeter curve with Limit Pressure and moduli denoted.

For calculation of the pressuremeter modulus the following expression, taken from

Menard method, is used.

( )

−

−

+++=

of

offocPMT VV

PPVVVE

212 µ

where

µ = is Poisson’s Ratio.

67

Vc is the initial volume of the pressuremeter

Vo and Po are the first point on the linear portion of the pressuremeter curve

Vf and Pf are the final points on the linear portion of the pressuremeter curve

Ground-Penetrating Radar

Test Proceeding

A high frecuenciy (25 –1000 KHz) electromagnetic pulse is transmitted from a

radar antenna into the ground. A receiver senses the energy reflected from various

interfaces in the ground analogous to seismic refraction. A trace of the reflected wave vs.

time (nanoseconds) is obtained. The relative magnitude of the reflected energy indicates

changes in the media penetrated (soil, rock, air, water, metal, drugs, money, etc)

The GPR receiver records a train of reflected pulses for which a seismic reflection

analogy is appropriate. The two survey methods used in seismic reflection (common

offset and common midpoint) are also used in GPR. Figures 3.15 a and b illustrate these

two modes. The typical GPR survey is conducted using the common-offset mode, where

the receiver and transmitter are maintained at a fixed distance and moved along a line to

produce a profile, consisting of multiple traces. Figure 3.16 illustrates the procedure.

Note that as in seismic reflection, the energy does not necessarily propagate only

downwards and a reflection will be received from objects off to the side. An added

complication with GPR is the fact that some of the energy is radiated into the air and, if

reflected off nearby objects like buildings or support vehicles, will also appear in the

record as arrivals. Shield antenna and fiber optic cables help to minimize these unwanted

reflections.

68

Figure 3.15a. GPR Reflection method, using common offset mode (Annan 1992)

Figure 3.15b. GPR reflection method, using common midpoint mode (Annan 1992)

Figure 3.16. Schematic illustration of common offset single fold profiling (Annan 1992)

69

Table 3.4. Typical antenna work performances (US Army 1995)

Device

The frequency of the antenna is chosen based on the desired depth of penetration

and the anticipated target size (see Table 3.4).

The data acquisition system typically consist of a laptop computer which stores and

displays the data collected.

Fieldwork

A GPR crew consists of one or two persons. Typically one crew person moves the

antenna or antenna pair along the profiles and the other operates the recorder and

annotates the record so that the antenna position or midpoint can be recovered.

The site-to-site variation in velocity, attenuation, and surface conditions is so large,

that seldom can the results be predicted before field work begins. Additionally, the

instrument operation is a matter of empirical trial and error in manipulating the

appearance of the record. Thus, the following steps are recommended for most field

work:

22. Unpack and set up the instrument and verify internal operation.

23. Verify external operation (one method is to point the antenna at a car or wall and slowly walk towards it. The reflection pattern should be evident on the record).

70

24. Calibrate the internal timing by use of a calibrator.

25. Calibrate the performance by surveying over a known target at a depth and configuration similar to the objective of the survey (considerable adjustment of the parameters may be necessary to enhance the appearance of the known target on the record).

26. Begin surveying the area of unknown targets with careful attention to surface conditions, position recovery, and changes in record character.

GPR surveys will not achieve the desired results without careful evaluation of site

conditions for both geologic or stratigraphic tasks and target-specific interests. If the

objectives of a survey are poorly drawn, often the results of the GPR survey will be

excellent records which do not have any straightforward interpretation. GPR surveys are

much more successful when a calibration target is available, GPR can be useful in

stratigraphic studies; however, a calibrated response (determined perhaps from backhoe

trenching, borings or soundings) is required for the most accurate interpretation.

Electrolresistivity

The Electroresistivity is a geophysical method used to obtain graphical

stratigraphy. A set of several electrodes 28 –56 are situated evenly, in the ground in

straight line connected to a power supply line. A computer is used to alternate powerand

voltage measurement between groups of electrodes and collect the data measured. The

depth of the scanning is about one half of length of the line.

Equipment. Electrical Resistivity Imaging (ERI)

The FDOT ones a Sting R1 Memory Earth Resistivity Meter, Swift Interface

Device, with 28 to 56 (18-inch) stainless steel electrodes, and 405 to 540-foot “smart

cables”, manufactured by Advanced Geosciences, Inc., (AGI) Austin, TX.

71

The Swift “smart electrode” system is designed for efficient acquisition of large

amounts of resistivity data when performing resistivity-imaging surveys. A complete

system consists of one interface box and up to 254 electrode switches (typically 28)

“smart electrodes” placed on electrode stakes and connected by a multi-lead cable to the

central interface unit. The switches are capable of connecting any combination of the

Sting terminals (A, B, M, N) to each electrode.

The Swift system is controlled directly by the Sting RI unit. The Sting can

automatically run a complete dipole-dipole survey or any customer programmed array

(i.e. Schlumberger, Wenner, pole-pole, pole-dipole, square array etc.). A laptop computer

can be connected to the Sting/Swift system to facilitate data download and in-situ

processing.

Soil Properties Directly Measured During Test

This test measures the apparent resistivity ρ, these values change when new soils

are encountered. The resistivity is a physical property, similar to density, which

characterizes the soil mass, and through an inversion technique can be used to assign

individual resistivity values to specific portions of the soil mass.

Applications of Technique

• Scan through electrically conductive surficial material, such as clayey soils, to determine the depth to electrically resistive bedrock, such as limestone and most other rocks.

• Image the depth and size of soil cavities in clay, caves in bedrock and abandoned mines.

• Find and map the subsurface extent of faults, fractures, dikes and veins having different electrical properties than the surrounding host rock.

• Use vertical electrical sounding, “electrical drilling”, to detect different horizontal geological layers.

72

• Mapping of pollution plumes.

ERI Test Procedure and Data Reduction

• An Electrical current (DC) is applied to electrodes inserted into the ground along the survey line from the Sting unit, through the “A” and “B” current leads (connected to two of the array electrode stakes), and propagates in all directions into the soil.

• The electrical potential difference is then measured between the “M” and “N” potential leads (connected to two other array electrode stakes) and collected into memory in the Sting unit.

• The Swift unit facilitates the electrical switching of the current and potential leads between the electrode stakes in an automated and efficient manner.

• The Sting unit processing software then converts the measured potential differences (in Volts) into a resistivity value based on the electrode array configuration and spacing distances.

• The Swift unit progressively assigns different metal stakes along the transect line as “current”, and alternately “potential” electrodes, moving the survey down the line, increasing the distance between electrodes at each new measurement (Fig 3.16).

• As the distance between electrodes increases, the depth of measurement increases, forming collectively, an inverted triangular distribution of data points beneath the survey line.

• These data points represent the distribution of apparent resistivity values in the soil and form the raw data that will then be evaluated using the RES2DINV software to produce a two-dimensional (2-D) model or “image” of the soil electrical resistivity beneath the survey line.

• The software produces a contoured profile of soil resistivity values, which will then be analyzed and interpreted as to geotechnical and geologic significance (Figure 3.17).

• The significance of the different array types relies on the different spacing and alignment of the electrode stakes to collect resistivity data that varies as to resolution, target depth, sensitivity and targeted geologic features (Fig 3.18).

• Each array type has its strengths and limitations, which can be used to advantage in designing a specific geophysical and/or geotechnical investigation to suit the needs of the client.

73

Figure 3.16. Diagram of a Dipole-Dipole array configuration. Current (A and B)

electrode and potential (M and N) electrode locations as survey progress down the transect line from left to right. The depth of measurement increases as spacing between electrodes pairs increases (Advanced Geosciences, Inc.,1998).

Figure 3.17. ERI profile of contoured resistivity values beneath survey line using

RES2DINV software. Top pictured is measured values; middle picture is calculated values of apparent resistivity; bottom picture is a best-fit model of resistivity (Advanced Geosciences, Inc., 1998)

74

Figure 3.18. Electroresistivity electrode array configurations(Advanced Geosciences,

Inc.,1998)

75

Triaxial Testing

Initial Measurements

After a soil sample is extracted from a Shelby Tube, measurements of the sample

must be taken in order to reduce the data.

27. Equation

tDDD

D bcto 2

22

−

++

=

Do = Initial Diameter.

Dt = Diameter at top.

Dc = Diameter at center.

Db = Diameter at base.

t = Membrane thickness.

28. Equation

bcto HHHH −−=

Ho = height of the sample.

Ht = height of soil sample mounted on the triaxial cell, ready for testing.

Hb = height of the based of triaxial cell including, pore stone and filter.

Hc = Height of loading cap, including, pore stone and filter.

76

SoilSampleHt

Hb

Hc

Ho

Figure 3.19. Triaxial cell, height measurement

29. Equation

Vo=HoAo

4

2o

oD

Aπ

=

30. Equation

Weight of Solids,

Ws = W / (1+w)

31. Equation

Volume of Solids,

ws

ss G

WV

γ=

32. Equation

Void Ratio,

wGSoe =

33. Equation

Area after saturation,

As = Ao (1-2ε1)

77

34. Equation

Area correction after shear for Q and R test,

Ac’=Ac/ (1-ε1)

Ac = Area after consolidation.

For S test,

cc

c AV

V

A11

1

'ε−

∆−

=

Fundamental Relationship Equations

o Equation σ3= Chamber Pressure

o Equation σ1= σ3 + σd

o Equation 3 σ 3’= σ3 – u

o Equation σ1’= σ3’ + σd

o Equation P= (σ1 + σ3)/2

o Equation Q= (σ1 - σ3)/2

o Equation A’= ∆U/∆σd

o Equation ∆U= B[∆σ3-A(∆σ1-∆σ3)]

o Equation εv = ε1+ 2ε3

o Equation ε3 = ε1+ 2σ3

78

Figure 3.20. Mohr circles and envelopes

2)(

2)(

sin31

31

σσ

σσ

φ+

−

= or )2

45(tan 2

3

1 φσσ

+=

Test Procedure

In order to test cohesionless soils, they were frozen inside the Shelby tube before

sample extrusion. In this fashion, the cohesionless soil can be extruded and trimmed into

samples with minimal disturbance. This action also helps to keep the sample together,

maintaining the shape, while it is handled in order to be placed inside the rubber

membrane and clamped to the base of the cell. Suction (vacuum) is then applied to give

the sample sufficient strength to stand while the dimensions are measured and the cell

assembled.

In order to obtain fully saturated specimens, back pressure is applied to dissolve the

gasses in the voids, tubing etc. by placing them into solution. The technique is to increase

79

the chamber pressure and pore pressure simultaneously so there is no change in effective

stress.

During the consolidation stage the chamber pressure within the triaxial cell is

increased without increase in pore pressure and this causes the water from the sample to

be expelled. Saturation volume changes will occur in partially saturated soils, and

subsequent volume changes occur as consolidation continues. During the shearing of the

specimen the deviatoric (vertical) stress on the specimen is increased and the valves on

the chamber are adjusted as needed or demanded by the type of test performed, CU, UU,

CD.

CHAPTER 4 INSITU TESTING FOR SITE CHARACTERIZATION

Insitu Testing

In order to obtain a well-characterized soil profile at the FDOT-UCF site a total of

32 well-known soil insitu tests were performed at several locations throughout the site.

Special attention was given to the corners and center of the property, leaving a minimum

of untested spots. In order to avoid disturbance of material due to the proximity of

equipment a minimum safe distance was kept at all times between the different boreholes.

See pictures of testing in attached CD. Figure 4.1 presents a plan view of the site, and the

survey results with co-ordinates location of the test and which Agency performed it.

To evaluate operator effects, the following testing matrix was used:

• SPT tests were performed by commercial drillers; Nodarse and Assoc., Universal Testing, and FDOT drillers from District 1 – Bartow

• FDOT State Materials Office (SMO), the University of Florida (UF), and Ardaman and Associates (mini-cone) performed CPT tests

• DMT tests were performed by FDOT District1, SMO, and UF

• PMT tests were performed by SMO and UF.

• FDOT State Materials Office (SMO) performed the Electro resistivity test.

• All Coast Engineering, Inc. performed the GPR test.

The Table 4.1 Summarizes the testing program and agencies involved.

80

81

Table 4.1. Summary of testing program and responsible agency

Test Type Agency SPT CPT DMT PMT GPR Electro

Resistivity

Energy Measureme

nt Performed

Nodarse 2Universal 2Ardaman 2

FDOT SMO Gainesville 5 1 3 4

FDOT Dist 1 Bartow 2 5 1 1

UF 5 2 1Coast

Engineering, Inc

Entire site

GRL 5

The scope of the work was to provide a full suite of insitu characterization tests at

the site; i.e., SPT, CPT, DMT, PMT. Inasmuch as the SPT is the most common insitu

test, used by geotechnical engineers, special attention was given to the comparison

between ; (1) drilling operators, (2) hammer type (safety vs. automatic), and (3) cased vs.

drilling mudded holes. Energy measurements were also conducted to compare the SPT

data. Energy measurements were performed by GRL and FDOT (SMO), Gainesville.

82

Figure 4.1. Plan view of the site with the exact location of the tests performed

83

Presentation of Test Results


SPT test location

The exploration program consisted of initially performing five (5) Standard

Penetration Test (SPT) borings. Subsequently, 2 borings to 200 ft. were performed; one

in the “hard’ NE corner, and the other in the “soft” SW corner. Shelby tube samples were

taken from these latter 2 borings. The results of the field exploration, description of the

soil type, N-values, and depth of exploration at each boring location are graphically

summarized on the soil profiles presented in Appendix A (see boring logs SPT 1 to SPT

7).

The SPT borings were performed at the locations shown in the boring location plan

(Figure 4.1). The borings were advanced to a depth of 60 feet below the ground surface.

Split-spoon soil samples recovered during performance of the boring were visually

classified in the field and representative portions of the samples were transported to

FDOT-SMO laboratory in sealed sample jars for classification.

The two commercial SPT rigs (Nodarse and Universal) used a safety hammer,

while FDOT District 1-Bartow used an automatic hammer.

Ground water elevation

Measurements of the ground water level (GWT) at the site were taken from the

boreholes on the day drilled after stabilization of the down hole water level. These levels

where encountered at depths of approximately 3 feet below the ground surface. Recently

performed measurements of the GWT founded this level as high as 1.5 below surface.

84

Grain size distribution

The FDOT-SMO and UF Labs performed visual classification and sieve analysis,

on samples retrieved from the SPT soil borings. With the exception of the FDOT District

1- Bartow rig, the rest of the rigs performed continuous sampling of the soil from the

surface to the depth of 10 feet. From the depth of 10 feet to the end of boring samples

were taken every 5 feet. In general the information obtained from the sieve analysis at

the lab confirmed visual description of the stratification shown on the boring logs SPT 1

to SPT 5. The generalized soil profile is as follows:

• from 0–5 feet a Poorly graded Sand, little or no fines.

• from 5–30 feet Sand to Silty Sand; sand –silt mixtures

• from 30–52 feet Clayey sands to Clayey Silt. With some gravel and shells

• from 52–60 feet shelly silty cemented Sand (Gravely Sand).

Tables 4.2 to 4.6 present the sieve analysis results provided by FDOT-SMO

laboratory.

Table 4.2. Grain size distribution Bartow SPT 1 samples logged in 2/5/02

Boring No.

Sample No. Depth

% moisture

organic content

(%)AASHTO

class.Unified class.

passing 1/2

passing 3/8

passing #4

passing #10

passing #40

passing #60

passing #200 % clay % silt % sand

LL/PI (%)

1 1 0-1.5 6.2 A-3 SP 100 98 87 31 2 5.0-6.5 38.8 1.0 A-3 SP 100 97 84 31 3 10.0-11.5 25.1 A-2-4 SM 100 99 96 181 4A 15.0-16.5 28.0 A-2-4 SM 100 99 98 191 4B 16.5-18.0 28.9 A-2-4 SM 100 100 99 151 5 20.0-21.5 28.4 A-4 SM 100 100 99 46 19 27 54 NP 1 6 25.0-26.5 26.9 A-3 SP-SM 100 99 95 71 7 30.0-31.5 30.3 A-2-4 SM 100 100 99 161 8 35.0-36.5 37.0 3.7 A-4 CL 100 99 99 51 21 30 49 31/ 91 9 40.0-41.5 31.1 A-2-4 SM 100 99 91 35 12 23 65 NP 1 10 45.0-46.5 28.0 A-4 SC 100 99 97 39 17 22 61 23/ 71 11 50.0-51.5 30.8 A-6 SC 97 94 85 85 81 78 43 16 27 57 31/ 131 12 55.0-56.5 21.5 A-1-B SP-SM 94 93 88 77 36 24 61 13 60.0-61.5 23.0 A-1-B SP 86 79 64 54 31 20 4

85

Table 4.3. Grain size distribution Bartow SPT 2 organic

Boring No.

Sample No. Depth

% moisture

content (%)

AASHTO class.

Unified class.

passing 1/2

passing 3/8

passing #4

passing #10

passing #40

passing #60


LL/PI (%)

2 1 0-1.5 5.9 A-3 SP 100 97 85 42 2 5.0-6.5 23.7 1.2 A-3 SP 100 96 84 42 3 10.0-11.5 22.4 A-2-4 SM 100 99 94 19 NP2 4 15.0-16.5 26.6 A-2-4 SM 100 100 100 212 5 20.0-21.5 27.6 A-2-4 SM 100 100 99 34 14 20 66 NP2 6 25.0-26.5 25.1 A-2-4 SM 100 97 91 142 7 30.0-31.5 28.2 A-2-4 SP- SM 100 99 98 112 8 35.0-36.5 30.2 A-4 SM 100 100 98 42 18 24 58 NP2 9 40.0-41.5 31.6 A-2-4 SM 100 99 92 22 13 9 78 NP

86

Table 4.4. Grain size distribution Universal SPT 1 samples logged in 4/23/02

Boring No.

Sample No. Depth Tare

wt. weight +

tare

dry weight +

tare%

moisture

organic content (%)

AASHTO class.

unified class.

passing 3/4

passing 1/2

passing 3/8

passing #4

passing #10

passing #40

passing #60


LL/PI (%)

1 1 1.0-2.5 373.0 511.9 500.0 9.4 A-3 SP-SM 100 98 87 52 2.5-4.0 366.0 517.4 494.8 17.5 A-3 SP 100 97 87 33 4.0-5.5 304.8 417.7 398.4 20.6 A-2-4 SM 100 98 88 134 5.5-7.0 305.0 413.6 395.3 20.3 2.6 A-3 SP-SM 100 97 89 105 7.0-8.5 313.0 404.8 391.7 16.6 A-2-4 SM 100 100 99 206 8.5-10.0 304.7 480.3 450.7 20.3 A-2-4 SM 100 100 98 237 13.0-14.5 371.4 510.9 482.5 25.6 A-3 SP-SM 100 100 99 108 17.0-18.5 366.7 515.1 469.8 43.9 A-2-4 SM 100 100 99 159 23.0-24.5 308.9 511.8 488.9 12.7 A-3 SP-SM 100 97 86 610 27.0-28.5 298.7 340.4 329.8 34.1 100 100 100 47 14 33 5311 33.0-34.5 368.1 441.3 420.8 38.9 A-2-4 SM 100 97 89 1412* 38.0-39.5 328.3 505.4 450.3 45.2 A-6 CL 100 100 100 68 18 50 32 38/1413 43.0-44.5 427.5 472.8 462.5 29.4 A-6 SC 98 96 94 42 12 30 58 29/1214* 48.0-49.5 363.4 576.6 521.5 34.9 A-4 SC 89 82 78 46 14 32 54 30/1016* 58.5-60.0 308.1 598.8 546.1 22.1 A-2-4 SM 97 91 80 63 54 51 35 16

87

Table 4.5. Grain size distribution Universal SPT 2

wt. dry organic Boring No.

Sample No. Depth Tare

weight + tare

weight + tare

% moisture

content (%)

AASHTO class.

unified class.

passing 3/4

passing 1/2

passing 3/8

passing #4

passing #10

passing #40

passing #60


LL/PI (%)

2 1 1.0-2.5 428.4 540.5 530.2 10.1 A-3 SP 100 98 87 32 2.5-4.0 432.5 511.7 499.7 17.9 3.1 A-3 SP-SM 100 98 87 63 4.0-5.5 428.2 479.8 473.0 15.2 A-2-4 SM 100 96 84 144 5.5-7.0 432.0 553.2 537.5 14.9 A-2-4 SM 100 96 82 195 7.0-8.5 432.5 552.1 533.8 18.1 A-2-4 SM 100 96 80 136 8.5-10.0 431.3 533.6 516.6 19.9 2.6 A-3 SP-SM 100 97 81 97 13.0-14.5 428.3 578.9 549.2 24.6 A-3 SP 100 100 98 48 17.0-18.5 301.1 466.7 434.3 24.3 A-4 SM 100 100 100 389 23.0-24.5 433.0 579.6 549.4 25.9 A-3 SP-SM 100 100 97 710 27.0-28.5 431 574.5 542.8 28.4 A-2-4 SM 100 100 100 2711* 33.0-34.5 429.1 602.6 535.7 62.8 A-7-6 CL 100 95 92 55 41/1512* 38.0-39.5 431.1 600.7 550.8 41.7 A-4 SC 100 99 98 45 15 30 55 31/1013* 43.0-44.5 423.1 682.2 620.7 31.1 100 99 99 36 14 22 6414* 48.0-49.5 435.2 673.5 623.7 26.4 A-4 SM 100 98 86 83 81 4515* 53.0-54.5 431.1 769.1 702.8 24.4 A-1-B SM 95 93 91 83 58 40 33 1416* 58.5-60.0 431.8 744.6 683.5 24.3 A-1-B SM 100 94 89 73 59 40 31 16

88

Table 4.6. Grain size distribution Nodarse SPT1 samples logged in 5/7/02

Boring No.

Sample No. Depth % moisture

organic content

(%)AASHTO

class. unified class.passing

1"passing 3/4"

passing 1/2"

passing 3/8"

passing #4

passing #10

passing #40

passing #60


LL/PI (%)

1 1 0.0-1.5 0.9 5.5 A-3 SP-SM 100 97 85 62 1.5-3.0 8.6 A-3 SP-SM 100 98 88 53 3.0-4.5 17.2 A-2-4 SM 100 98 89 194 6.0-7.5 19.2 A-2-4 SM 100 100 98 145 13.5-15.0 26.0 A-4 SM 100 100 99 376 18.5-20.0 26.0 A-3 SP-SM 100 99 94 67 23.5-25.0 28.5 A-2-4 SM 100 100 100 218 28.5-30.0 33.8 A-4 SM 100 100 99 41 15 26 59 28/29* 33.5-35.0 33.7 A-2-4 SM 100 99 96 83 47 41 27 10 17 73 NP

10* 38.5-40.0 64.0 A-7-5 MH with sand 98 93 90 84 84 83 74 22 52 26 55/25

11* 43.5-45.0 47.6 A-6 sandy-CL 97 96 95 95 94 66 16 50 34 40/1612* 48.5-50.0 24.6 A-2-4 SM 96 93 93 91 91 69 58 17

13* 53.5-55.0 29.4 A-2-4 SM-with gravel 97 91 79 73 53 44 15

14* 58.5-60.0 13.8 A-1-b SP-SM-with gravel 84 79 72 69 61 52 38 30 12

89

90

Standard Penetration Test with Energy Measurements

The SPT is the most common field test performed in Florida, and engineers are

more comfortable with the data interpretation from this test. Due to the variability of the

data obtained from one company even from one driller to other, the tests were performed

in groups or very close to each other in order to perform comparisons of the blow counts

at the same depth. To be able to measure test variability during drilling operations, the

rigs were instrumented and variation of energy was measured.

Group east

Bartow SPT # 1 and # 2 are located in the same area of the site on a straight-line

heading North (see Figure 4.1). At the location of this group of borings the goal was to

try to compare the use of a hollow stem auger (Bartow 2) versus the use of casing

(Bartow 1) to maintain an open hole. The same automatic hammer was used to perform

both tests. As shown in the Figure 4.2, little difference between the boring results was

found. The SPT-N blow counts at the same depth is very similar, but the simultaneous

energy measurements indicate substantial differences between the two borings. Both

boreholes were drilled using an automatic hammering. Note that there may be errors

associated with the energy measurements for Bartow SPT 1 by SMO due to a bad cable,

energy measurement at 40 feet was aborted. GRL assisted with simultaneous

measurements and assisted SMO personnel with troubleshooting the system (see Table

4.7).

91

Table 4.7. Uncorrected SPT analyzer data group east Bartow SPT 1 Bartow SPT 2

PDI SMO SMO

Depth (ft)

SPT Analyzer Energy Rating

(%)


(%)

Depth (ft)


15 85.5 79.1 15 68.7 30 81.9 92.25 30 68.7 40 83.9 XX 40 72.3

Figure 4.2. Energy analysis SPT group east

92

Group west

Universal SPT 1 versus Nodarse SPT 1 are located on a line from East to West (see

Figure 4.1). At the location of this group the goal was to compare safety hammer

performance between two different companies/drill rigs. From the data shown in Figure

4.3, it is possible to observe a difference of blow counts in the same layer of sand from

depths of 8 to 25 feet. The Universal crew reported a higher blow count than Nodarse’s

crew. These results agree with the difference of energy measurement in this layer. See

Table 4.8 below, where at 15 feet the energy measurement results are 57 % for Nodarse’s

rig and 65% for Universal’s rig. But would this 8% of difference explain the discrepancy

between the N-values of 2 vs.19? A more reasonable conclusion is drawn when compare

this data with information collected with CPT. The Universal rig was performed near

SMO CPT-5 (see Figure 4.1), denoted with a high value of tip resistance qc = 280 tsf,

(see Figure 4.48). The high value of blow counts, N-value is also influenced by the

presence of the hard pan layer located between 8 to17 feet at the East side of the research

site.

93

Table 4.8. SPT analyzer data group west

Nodarse SPT 1 PDI

Universal SPT 1 PDI

Depth (ft)


(%)

Depth (ft)


(%) 15 57 15 65.3 30 65 30 66.2 40 69.4 40 68.9

Figure 4.3. Energy analysis SPT group west. Appreciable difference exist between the

SPT’s from 8 to 17 feet. Probable cause is due to existence of hardpan layer located at this same depth. Both are mudded holes (Bentonite)

94

Comparison of all SPT data

Table 4.9 summarize the N values obtained from the 7 SPT performed at the site.

Figure 4.5 presents a comparison of the N-values obtained from the 7 SPT borings

at the site. The figure illustrates that in spite of the local difference between N values at

different depths, in general, these values yield a well-defined trend line. Based on the

SPT test information the conclusions is that the area selected for the test is very uniform,

showing a slight difference in the East and Center sides, where a hard pan sand layer is

located at depths of 7 to 17 feet below grade.

Figure 4.4 is an interpretation for the general site stratigraphy, based on the 7 SPT

test results. The N-values shown at each side of the profile are uncorrected values

obtained directly from tests not average values. These values are considered to be more

representative of the real nature of each layer. An apparent difference is appreciated

between East and West side of the site due to the presence of the hardpan layers in the

East Center Side at depth 10 and 25 feet.

20

60

45

6

20

15

30

15

0

PROFILE WESTDEPTH

AT 60 FEETEND OF BORING

SILTY SANDS,

48 - 60 feet

30 - 48 feet

5 - 30 feet

WITH SOME GRAVEL AND SHELLS

SHELLY SILTY CEMENTED SAND

SANDS 0-5 feetPOORLY GRADED

SAND-SILT MIXTURES12

10

CLAYEY SANDSSILTY CLAYS

HARDPANLOCATION

17

5

12

3121

25

48

PROFILE EASTN- VALUE N- VALUE

8

20

Figure 4.4. General site stratigraphy from summary of 7 SPT tests. Notice the difference

between East and West side due to hardpan layers

95

Table 4.9. Summary of the uncorrected N-values obtained at the site from 7 SPT Agency Bartow1 Bartow2 Nodarse Universal1 Universal2 GEC -1 GEC - 2Depth(ft)

0 0 0 0 0 0 0 00.5 7 7 81.5 4 7 8 8 143 10 10 205 14 20 11 9 17 18 147 11 19 318 7 24 29 10 710 23 22 11 24 2413 7 1115 7 8 2 19 14 7 517 7 5 19 10 15 620 3 6 10 1122 6 825 17 20 1 3 19 13 228 8 030 4 4 0 0 3 5 033 4 535 0 3 7 3 0 6 1138 4 440 0 1 4 4 0 5 443 6 445 4 4 15 8 6 748 5 850 7 11 24 13 7 953 9 1255 16 9 21 24 19 1658 14 1260 50 21 19 31 11 21

Blow counts N

4

7

96

Figure 4.5. Typical trend of uncorrected N values from 7 SPT at FDOT-UCF site

97

N-value correction

In order to address the differences on Energy measurements, and N-values in the

FDOT-UCF site, a comparison of the corrected N-values was needed. The objective was

to compare outcome from energy correction with previous results.

Based in the proceedings for N-value correction suggested by Bowles (1996), (see

Chapter_3), the following adjustment factors were used.

• CN, the adjustment for effective overburden pressure p’o was disregarded.

• Sampler correction η3 = 1

• Borehole diameter correction η4 = 1

• Correction for rod length were made as follow:

For the East group considering the use of an Automatic Hammer E* = 70%, comparing different drilling techniques:

Bartow SPT1 %2.900.19.83

95.09.81

85.05.85

31

=

++=riE (for, Casing)

Bartow SPT2 %1.750.13.72

95.07.68

85.07.68

31

=

++=Eri (for, Hollow Stem Auger)

*EE

valueNdNcorrrecte ri∗−=

For the West group considering the use of Safety Hammer E* = 60%, comparing different drill rigs, Universal SPT 1 vs. Nodarse SPT 1.

Nodarse SPT 1 %3.680.14.69

95.065

85.057

31

=

++=riE

Universal SPT 1 %8.710.19.68

95.02.66

85.03.65

31

=

++=riE

*EE

valueNdNcorrrecte ri∗−=

A summary of N-value correction is shown in Table 4.10 and Figure 4.6.

98

Table 4.10 Summary of corrected N-values obtain from SPT test where energy measurements were performed

Agency Bartow 1 Bartow2 Nodarse Universal 1Rod lengthCorrection

Average Eri 90.2% 75.1% 68.3% 71.8%Rig efficiency 70.0% 70.0% 60% 60%Depth(ft)

0 0 0 0 0 0.70.5 8 0.751.5 5 8 9 10 0.753 11 125 18 22 13 11 0.757 13 238 8 29 0.75

10 30 24 13 29 0.751315 9 9 2 23 0.8517 9 6 23 0.8520 4 72225 22 22 1 4 0.952830 5 4 0 0 0.953335 0 3 8 4 13840 0 1 5 5 14345 5 5 18 14850 9 13 29 15355 21 11 26 15860 65 24 23 1

Blow counts N5

0.75

0.75

99

0

10

20

30

40

50

60

70

0 20 40 60 80

N-value

Dep

th (f

eet)

Bartow 1Bartow 2NodarseUniversal 1

Figure 4.6. Typical trend of corrected N-values from SPT test where energy

measurements were performed

Analysis of data compared shows little difference with previous results.

• Bellow the 25 feet the uniformity of the site is noticeable showing little difference between East and West side.

• The N-corrected values from Universal SPT 1 located in the West side, show more similarity with the N-corrected values of the East group, than with values from Nodarse SPT 1.

• Comparison of these results with data collected with CPT indicated that the hardpan layer located between depth 7 to 17 feet, in the East-Center area of the site, also reach the West side of the site (Universal SPT 1 Location), see Figure 4.1.

100

Dilatometer Test (DMT)

DMT layout

A total of four DMT soundings were performed at the site, using the UF, FDOT-

SMO, and FDOT District 1 cone trucks. These tests where located near a SPT test in

order to make a future comparison of data interpretation.

Data comparison of DMT tests

In order to make the comparison of data from UF DMT 1 and SMO DMT, the two

soundings were located relatively close to each other in the East Group of SPT tests. The

same approach was also taken to compare UF’s DMT 2 with District 1’s DMT. These

soundings where located at the West Group of SPT tests (see Figure 4.1). The graphs in

Figures 4.7 and 4.8 present results from the four DMT borings and establish a

comparison at each group location.

DMT results

A comparison of the DMT data presented in Figures 4.7 and 4.8 show little

difference between the plots. Consequently, there is little variation between the DMT

equipment and data reduction thereof; i.e., reliable.

The comparison between the two groups, East and West, corroborate the

information obtained through the SPT tests. This is the existence of a hardpan layer of

sand or silty sand in the East section of the site. This layer was not found on the West

area of the site. The DMT located the Hardpan layer at a depth of 10 feet.

The description of soil stratification obtained with the data reduction of the DMT

test agrees with the description given by the sieve analysis and visual classification of

samples obtained from the SPT tests.

101

General soil stratification from DMT concludes:

• from 0–5 feet Sand.

• from 5–33 feet Silty Sand to Sand

• from 33–52 feet Clayey Silt to Sandy silt with seams of Clay.

Reduced data showing the actual numbers has been added to the electronic report to

FDOT, and is not part of this document. Please see the CD accompanying the FDOT

report for more information.

University of Central Florida FDOT Research SiteDMT Location 1

SMO UF Blue

Thrust

0

2

4

6

8

10

12

14

16

18

20

0 5000 10000 15000qD (KGF)

Dep

th (m

)

P0

0

2

4

6

8

10

12

14

16

18

20

0 20 40(bar)

P1

0 50 100(bar)

KD

0 50 100(--)

ID

0 10 20(--)

ED

0 1000 2000(--)

Red

Figure 4.7. DMT results for comparison between UF DMT 1 and SMO located at east group of SPT tests

102

University of Central Florida FDOT Research SiteDMT Location 2

Bartow BlackUF Blue

Thrust

0

2

4

6

8

10

12

14

16

18

20

0 2000 4000qD (KGF)

Dep

th (m

)

P0

0

2

4

6

8

10

12

14

16

18

20

0 10 20(bar)

P1

0 20 40(bar)

KD

0 20(--)

ID

0 5 10(--)

ED

0 500 1000(--)

Figure 4.8. DMT results for UF DMT 2 and FDOT District 1 located at west Group of

SPT tests

Comparison of the soil properties between West side and East side using reduced

data from DMT is shown in Figure 4.9. Analysis of the Over Consolidation Ratio (OCR)

and Constrained Modulus (M) graphs confirm the existence of a hardpan layer at depth

10 feet in the East side of the site. The OCR values obtained at the site reveal the

presence of a heavily overconsolidated to a light overconsolidated soil profile, with the

exception of the Clay layer found between 30 to 37 feet in the sounding UF DM-1 (East

side), where the OCR values are less than 1. When OCR <1 soil is considered to be

underconsolidated. These results agree with information collected with SPT Bartow at

same depth N-value = 0.Values of Friction Angle φ are comparatively constant along the

entire site. Undrained shear strength (Su), values are slightly higher in the West side.

0.00

10.00

20.00

30.00

40.00

50.00

20 40 60φ (De gre e )

Dep

th (F

eet)

UF DM T 1 UF DM T 2

0 .0 0

1 0 .0 0

2 0 .0 0

3 0 .0 0

4 0 .0 0

5 0 .0 0

0 0.4 0.8 1.2Su (bar)

UF DM T 1 UF DM T 2

0 .0 0

1 0 .0 0

2 0 .0 0

3 0 .0 0

4 0 .0 0

5 0 .0 0

0 3000 6000M (bar)

UF DM T 1 UF DM T 2

0 .0 0

1 0 .0 0

2 0 .0 0

3 0 .0 0

4 0 .0 0

5 0 .0 0

0 200 400OCR

UF DM T 1 UF DM T 2

103

Figure 4.9. East vs. West comparison of reduced data from DMT

104

Cone Penetration Test (CPT)

CPT layout

A total of 15 CPT tests were performed at the site, using the UF, FDOT-SMO, and

FDOT District 1 cone trucks. In addition Ardaman and Associates performed 2 mini-CPT

tests. These tests were also located in the vicinity of the SPT’s influence zone in order to

make a future comparison of data interpretation. Due to the cone penetration test

reliability a larger number of these tests were performed at the site than with any of the

other tests. In addition, most of the participating companies on site have similar

equipment and lesser operator error was anticipated. This condition provides a good

opportunity for calibration of gear and accurate data interpretation. In order to obtain an

accurate description of the soil layers conforming the area, the CPT tests were located at

the corners and center of the site, the layout intend to leave the minimum of non tested

area possible.

Data comparison

The comparison between the participating companies at different locations of the

site is shown in Figures 4.11 to 4.16. In order to obtain a general idea of the soil profile

along the site 3 cross sections based on tip resistance are shown in Figures 4.17 to 4.19.

Locations of the cross section are seen in Figure 4.10.

CPT results

Comparison of CPT figures indicate that little or no-change is observed between

them. These results confirm or back up the soil stratigraphy results of the area obtained

with the rest of the equipment tested (DMT and SPT). This is:

105

• The data obtained with the cone confirm the existence of a hardpan layer located between 8 and 12 feet on the Center-East region of the site.

• The little change of values for tip resistance, friction ratio, etc shown in the charts is an indication of the relative uniformity of the site.

• The transition from a “Soft Material” to a “Hard Material” in the upper layer of sand and silty sand is easily appreciated (see cross sections in Figures 4.17, 4.18 and 4.19).

• The existence of a well-defined layer of silty clay or clayey silt from depth 33 to 50 feet in the entire area was confirmed by the test.

• The mini-CPT results are compatible with standard CPT test.

106

Figure 4.10. Location of CPT cross sections at the FDOT-UCF site

University of Central Florida FDOT Research SiteCPT Location 1

SM O Bartow k

UF Blue

Tip Resistance

0

5

10

15

20

25

30

35

40

45

50

55

60

65

0 100 200 300 400qc (tsf)

Dep

th (f

t)

Sleeve Friction

-1 0 1 2 3 4 5 6fs (tsf)

Friction Ratio

-1 0 1 2 3 4 5 6 7FR (%)

RedBlac

107

Figure 4.11. CPT soundings at NE corner location 1


SMO Bartow k

UF BlueArdaman Green

Tip Resistance

0

5

10

15

20

25

30

35

40

45

50

55

60

65

0 100 200 300qc (tsf)

Dep

th (f

t)

Sleeve Friction

-1 0 1 2 3 4fs (tsf) Friction Ratio

-5 0 5 10 15FR (%)

RedBlac

108

Figure 4.12. CPT soundings at NW corner location 2


SM O Bartow k

UF BlueArdam an Green

Tip Resistance

0

5

10

15

20

25

30

35

40

45

50

55

60

65

0 50 100 150 200qc (tsf)

Dep

th (f

t)

S leeve Friction

-1 0 1 2 3fs (tsf) Friction Ratio

-5 0 5 10 15 20 25FR (%)

RedBlac

109

Figure 4.13. CPT soundings at SW corner location 3

110


SMO Bartow k

UF Blue

Tip Resistance

0

5

10

15

20

25

30

35

40

45

50

55

60

65

0 200 400 600 800 1000qc (tsf)

Dep

th (f

t)

Sleeve Friction

0

5

10

15

20

25

30

35

40

45

50

55

60

65


-1 0 1 2 3 4FR (%)

RedBlac

Figure 4.14. CPT soundings at SW corner location 4

111


SM O Bartow k

UF Blue

Tip Resistance

0

5

10

15

20

25

30

35

40

45

50

55

60

65

0 100 200 300qc (tsf)

Dep

th (f

t)

Sleeve Friction


-1 0 1 2 3 4FR (%)

RedBlac

Figure 4.15. CPT soundings at center location 5

112


SMO Bartow k

UF Blue

Tip Resistance

0

5

10

15

20

25

30

35

40

45

50

55

60

65

0 100 200 300 400qc (tsf)

Dep

th (f

t)

Sleeve Friction

0 2 4 6 8 10fs (tsf) Friction Ratio

-1 0 1 2 3 4FR (%)

RedBlac

Figure 4.16. CPT soundings at south location 6 (South-Center)

113

University of Central Florida FDOT Research SiteCross section CPT 3-6-4

SMO Bartow k


CPT3 CPT6 CPT4

Tip Resistance

0

5

10

15

20

25

30

35

40

45

50

55

60

65

0 50 100 150 200qc (tsf)

Dep

th (f

t)

Tip Resistance

0 50 100 150 200qc (tsf)

Tip Resistance

0 50 100 150 200qc (tsf)

RedBlac

Figure 4.17. CPT soundings cross section show increasing tip resistance along SW to SE portion of the site


SMO Bartow k


CPT2 CPT5 CPT4

Tip Resistance

0

5

10

15

20

25

30

35

40

45

50

55

60

65

0 100 200 300qc (tsf)

Dep

th (f

t)

Tip Resistance

0 100 200 300qc (tsf)Tip Resistance

0 100 200 300qc (tsf)

RedBlac

114

Figure 4.18. CPT soundings show increasing tip resistance along NW to SE cross section of the site


SMO Bartow k


CPT3 CPT5 CPT1

Tip Resistance

0 100 200 300 400qc (tsf)

Tip Resistance

0

5

10

15

20

25

30

35

40

45

50

55

60

65

0 100 200 300 400qc (tsf)

Dep

th (f

t)

Tip Resistance

0 100 200 300 400qc (tsf)

RedBlac

115

Figure 4.19. CPT soundings show increasing tip resistance along SW to NE cross section of the site

116

Pencel Presuremeter Test (PMT).

PMT layout.

Two PMT tests were performed at the site, using the UF and FDOT-SMO cone

trucks. These tests were located near Universal’s SPT-2 test in order to obtain a soil

profile useful for making future comparisons of results and data interpretation. One

purpose was to calibrate the new Pressuremeter recently acquired by SMO. The goal was

to perform the tests in the field close to each other and compare results. Instructions on

how to calibrate the equipment before and after the test were provided by UF at a

previous meeting at the UF Geotechnical Laboratory. Instructions and software to

perform interpretation of collected data was also provided by UF.

Test results.

The comparison between the two PMT tests is shown in Figures 4.20 to 4.26. For

all depths compared, the results from both tests totally disagree. The UF results are much

stiffer than the comparison SMO results. The shape of the curves obtained from SMO

PMT show an atypical silhouette, creating sharp slopes on the loading parts of the curves,

and quite different from the UF PMT, which display a typical and expected curved shape.

117

Fully Corrected Pencel Pressuremeter Curve

0

2

4

6

8

10

12

14

-20 0 20 40 60 80 100

Volume (cm3)

Pres

sure

(Bar

)

SMO Pencel UF Pencel

Figure 4.20. Comparison graph of data interpretation from UF and SMO pressuremeter at depth 5 feet


0

2

4

6

8

10

12

-20 0 20 40 60 80 100Volume (cm3)

Pres

sure

(Bar

)

SMO PMT UF PMT


118


0

2

4

6

8

10

12

-20 0 20 40 60 80 100Volume (cm3)

Pres

sure

(Bar

)

SMO PMT UF PMT

Figure 4.22. Comparison graph of data interpretation from UF and SMO pressuremeter at

depth 15 feet


0

2

4

6

8

10

12

14

16

-20 0 20 40 60 80 100Volume (cm3)

Pres

sure

(Bar

)

SMO PMT UF PMT


119


0

2

4

6

8

10

12

14

-20 0 20 40 60 80 100Volume (cm3)

Pres

sure

(Bar

)

SMO PMT SMO PMT



0123456789

-20 0 20 40 60 80 100Volume (cm3)

Pres

sure

(Bar

)

SMO PMT UF PMT


120


0

2

4

6

8

10

12

14

-20 0 20 40 60 80 100

Volume (cm3)

Pres

sure

(Bar

)

SMO PMT UF PMT

Figure 4.26. Comparison graph of data Interpretation from UF and SMO pressuremeter at depth 35 feet

The information collected in the use of the SMO equipment suggest:

• More experience is required in the process of calibration, which is very tedious.

• The equipment is very new and the membrane of the pressuremeter probably needs to be further exercised.

• Another factor that could influence the information obtained is the fact that the UF equipment uses a slightly different tip shape.

• UF equipment uses a digital gage instead of the dial gage used by the equipment belonging to SMO during the process of reading. The digital gage helps the untrained eye during calibration and test process.

121

GPR Test

Test scope

There were several non-tested spots at the FDOT-UCF site. Ground Penetration

Radar (GPR) test was proposed as a solution to increase the amount of data available, and

cover the non-tested areas at the site. The objectives of the testing are:

• Obtain a series of profiles in order to generate a general characterization of the site.

• Compare results of test with data collected with the CPT, DMT and SPT in order to determine reliability of test.

Figure 4.27. Test was performed using the Ramac GPR, a 100 mHz antenna, shielded

with fiber optics in order to avoid external interference

Test layout

The test was performed by All Coast Engineering, Inc., using a 100 mhz antenna

(Ramac GPR) shown in Figure 4.27. A total of 22 scans were made at the FDOT–UCF

site. The scans were made from East to West, covering the entire site from North to

South. A distance of 15 to 18 feet was left between each pass. Additionally 2 scans were

made in diagonal direction. Scan 21, runs from NE corner to SW corner and scan 22 fron

NW to SE corner. Location of tests is shown in Figure 4.28.

122

Figure 4.28 Location of GPR test at FDOT-UCF research site

East West

Sand

Sand

Cla

yC

lay

SS

RR--55

East West

Sand

Sand

Cla

yC

lay

East West

Sand

Sand

Sand

Sand

Cla

yC

lay

Cla

yC

lay

SS

RR--55

123

Figure 4.29. Comparison of the GPR output from pass # 5 with GMS soil profile at same location. Data compared from 0 to 27 feet of depth

East West

Sand

Sand

Cla

yC

lay

SS

RR--1010

East West

Sand

Sand

Cla

yC

lay

SS

RR--1010

124

Figure 4.30. Comparison of the GPR output from pass # 10 with GMS soil profile at same location. Data compared from 0 to 30 feet of depth

125

Figure 4.31 All Coast Engineering Inc., crew performing the test. Immediate reading of

the antenna is sent to the portable computer, giving the operator an opportunity to control velocity of the pass, and direct detection of anomalies in the field

Conclusions

• The GPR test has shown good accuracy in the representation of the upper layers soil profile at the FDO-UCF site. Comparison with data collected with CPT, DMT and SPT, shows total agreement.

• The existence of a well-define layer of silty clay to clayey silt from depth 33 to 50 feet in the entire site, and the location of the water level as high as 1.5 feet bellow grade introduce a signal attenuation of the antenna. Poor information was gathered bellow depth 35 feet.

126

Electro Resistivity Test

Test scope

Three Electro Resistivity surveys were performed at the FDOT-UCF site, as part of

the geophysical study carried out in the research site. The tests were performed in order

to compare results with the reduced data obtained from the insitu testing i.e. SPT, CPT,

DMT. The objective was to calibrate and refine the abilities of the SMO personnel in the

use of their new equipment.

As was explained in the literature review section, the process of reducing the data

obtained with the use of electroresistivity test is a trial and error process. The software

reduces the data using a fast iterative process(seconds), without introducing error of

human interpretation to the results. However as with any software the computer program

requires proper input data from the field. The existence of backup data from other insitu

testing techniques is very important in order to obtain good quality comparison result,

with the use of this technology. Main results are stratigraphic profiles, without soil

properties.

Survey run # 1

The test was performed at the center of the site in a South - North direction,

perpendicular to the gate. The length of the run was 87 feet (27) m, using a spacing of 3

feet (0.91 m). The North side of the test is located in the immediate vicinity of SMO and

Bartow CPT- 5 test location. The South side is located in the vicinity of Universal SPT –

2; see Figure 4.32 for location of the test.

127

Figure 4.32. Location of electro resistivity surveys (Run) # 1 and 3 at the UCF site

128

Figure 4.33 shows the reduced data obtained from the output of the RES2DINV

software, designed for this propose. The plot is a two-dimension graph of length of the

test vs depth of penetration of the test. On the X- axis bar is shown the number of

electrodes used in the test (30) and the spacing between them, 0.91 m (3 feet). The

rainbow colors scale displayed below the graph is the range of true resistivity of the soil,

for this specific test.

The two-dimension profile shows the existence of at least four visible layers.

• From 0 to 2 feet = Sand.

• From 2 to 7 feet = Wet sands

• From 7 to 12 feet = Sand to silty sand.

• From 12 to13.8 feet = Sandy clay.

In a comparison of this profile with the data interpretation of the SPT and CPT

data in the vicinity of the test, it was determined that the results from the Electro-

resistivity test were very close to those inferred from the SPT and CPT test results.

Comparison of the data is shown in the Figure 4.33. Further study of the CPT borings

results indicate the location of the sandy clay layer to a depth 5 feet below the depth

found in the Electro Resistivity profile.

Survey (Run) # 2. The results obtained from this run were discarded due to

corruption of the input data obtained on the site. The performance of the test was affected

by the magnetic field created by the perimeter fence. The data reduced by the software

didn’t match the previous information given by the rest of insitu testing performed at the

site. As a result of this experience the personnel of SMO decided to keep a significant

distance from the perimeter fence and perform another survey.

129

Survey run # 3

The survey was performed at the center of the site in a Southeast - Northwest

direction. The length of the run was 250 feet (76) m, using a spacing of 8.9 feet (2.7 m).

The center of the test is located on the immediate vicinity of SMO and Bartow CPT- 5

and Universal SPT –2. The South end is located in the vicinity of GCE SPT –2. The north

end of the test is located in a “blind” area of the site but is close enough to the NW

corner, to be fairly well represented by the CPT data at that corner. See Figure 4.32 for

location of the test.

The results obtained with the use of the RES2DINV software indicate a complex

configuration in the soil profile. Visual comparison of this profile with the profile

developed for the same area of the site, by the use of the GMS software indicate a strong

similarity of results. See Figure 4.42 on GMS section. A thorough comparison of the data

presented using CPT and SPT data in the vicinity of this electro resistivity survey,

confirms that the Electro- resistivity test results provide a fairly accurate soil profile for

the experimental site area. The profile shown in fig 4.34 indicates a sand layer that tends

to be flat on the Northwest direction until dissipating into a silty sand layer. On the

Southeast direction the layer increase in thickness.

130

Figure 4.33. Interpretation of soil profile from test Run #1. CPT 5 and SPT Universal 2 were added to figure for visual comparison

131

Figure 4.34. Interpretation of soil profile from test Run # 3. CPT’s 3, 4, 5 and SPT Universal 2 were added to figure for visual comparison. The interpretation of data equals reduced data from CPT and SPT

132

Conclusions

The Electro Resistivity Test has shown good accuracy in the representation of the

soil profile at the FDOT-UCF site. The existence of the back up SPT and CPT data was

of key importance to properly calibrate the results. Inasmuch as the ER data reduction

software is a “signal-matching” operation, knowledge of the site data allowed us to

reduce the trial and error inconvenience in the process of selection and calibration of

parameters.

Soil Profile

General soil description

The soils at the UCF-FDOT Site selected for this project are predominantly sand.

Based upon the insitu soil testing performed at the site the following conclusions were

made.

In general, the stratigraphy of the site is typically sand to silty sand overlying

clayey soil that is more prominent on the west side of the site (CPT groups 2, 3 and 5).

The presence of which was verified by the SPT and CPT borings. An extremely stiff

hardpan lens was found in the vicinity of the central group of CPT tests (SMO CPT 5 and

Bartow CPT5) and UF DMT1. Truck refusal was encountered by the CPT tests in that

area, and a total thrust of 11.5 tons was reached with the DMT for penetration.

The general SPT profile is as follows:

0 – 5 ft. Clean loose Sands at surface, N-values = 8-15

5 – 22 Silty sands, sand silt mixtures, N-values = 8-20.

22 – 48 Clayey sands to sandy clays mixed with silty sands, N-values = 5

48 – 60 Shelly silty cemented sand, N-values = 12-20.

60 feet End of Boring. A peak N-value of 50 was reached at this depth.

133

3D soil characterization

With the purpose of having a better graphical perspective of the soil stratigraphy, a

3D “view” of the site was performed using of the Software GMS (Groundwater Modeling

System). The goal was to delineate the change of soil properties between “different”

areas of the site. In addition, if successful FDOT may wish to consider using this

software for various projects.

The cone penetration test data were very useful in the design of a 3D view of the

soil stratification of the site. The GMS software, allows the user to translate information

collected directly from the cone truck (as tip resistance, friction ratio, soil stratification,

etc) into visual information in shape of borings logs on a 3D view. This software is able

to create several nets of triangular shape that interconnect information from different

borings. Areas not investigated with the cone truck are statistically analyzed and

information added by the software. As a final result, the information is given as a 3D

solid shape. The program also allows the user to obtain cross sections from the new 3D

solid model created. Figures 4.35 to 4.49 present these results.

In Figure 4.35, the different colors at each boring represent the stratification. As is

usual in this type of work the information obtained through the cone truck is extremely

detailed, for this reason the GMS software allows the user to edit the information of each

boring, in order to use only the essential data.

Figures 4.37 and 4.38 show differing three-dimensional views of the site. Figures

4.39 through 4.42 show various cross sections of the site.

Figures 4.48 and 4.49 illustrate general and more specific characterizations of

change in tip resistance, respectively. In Figure 4.48, each boring reflects the change of

tip resistance based on a palette of different color. The differences between the borings

134

are barely noticeable due to the nature of the soil at the site. Change of Qc software

values along the site is not significant. The greens strips located at the top of East

borings represents position of the ‘hardpan” layer. In Figure 4.49, each boring reflects

the change of tip resistance based on a palette of different color vs depth. The differences

between the borings are more obvious, based on the color tip resistance. The scale on the

NE corner reaches the 350 tsf at depth 10 feet where the ”hardpan” layer is located vs. a

100 tsf reached by the borings at the SW corner at same depth. The goal for future work

will be to translate this information (tip resistance, sleeve friction, friction ratio, etc.) and

use it to draw profiles of soil properties similar to the ones shown in Figures 4.39 through

4.42. This will help to have a better description of soil properties.

Figures 4.43 through 4.47 illustrate successive overhead views of horizontal cross-

sections at depths of 5, 15, 30, 45, and 50 ft. On Fig 4.36 line A-A delineates the

separation between the “hard” NE corner and “soft” SW corner.

135

Figure 4.35. Relative location of the CPT, SPT and DMT borings performed at the site

136

Figure 4.36. Overhead view. Cross section A delineates the borderline between “soft” west area and “hard” east area. Hard Pan layer is located at depths 5 to 12 feet

137

Figure 4.37. 3D view of the site looking toward North, standing at SE corner

138

Figure 4.38. 3D View of the site looking towards South standing at NW corner

139

Figure 4.39. Cross section A is located on the border between “hard” and “soft” layer. Cross section B shows extension of a third layer of silty sand below the clay layer not seen on the general 3D view

140

Figure 4.40. Cross section A is located on the border between “hard” and “soft” layer. Cross section E shows the change of soil type from silty sand to sand in the upper layer (this cross section is located between the “hard” SW corner and “soft” NE corner)

141

Figure 4.41. Cross section C is characterizing the “soft” area to the West. Cross section D is characterizing the “hard” East. This is a typical example of the use of the software when designing piles. The information shown provides enough information to determine the extension of a soft layer sensitive to scour

142

Figure 4.42. Cross section characterizing FDOT-UCF site soil profile along the SE to NW edge

143

Figure 4.43.The overlaying hardpan and sand layers have been removed, exposing the steep shape characteristic of uppers layers at the site. Elevation of NW corner is 0 feet, elevation of SE corner is 30 feet

144

Figure 4.44. First layer of silty sand has been removed, exposing a second layer of sand below it. Overhead layer at 25 feet

145

Figure 4.45. SE corner view at depth of 30 feet. The overlying hardpan, and two sand layers have been removed exposing the “silty-sand” layer

146

Figure 4.46. SE corner view at depth of 45 feet. The overlying hardpan, two sand layers, and “silty-sand” layer have been removed exposing the “clay” layer. Overhead view at depth 33 feet

147

Figure 4.47. SE corner view at depth of 50 feet. The overlying hardpan, two sand layers, “silty-sand”, and “clay” layers have been removed exposing the medium cemented sand layer. Overhead view at depth of 50 feet

148

Figure 4.48. General tip resistance characterization of the site

149

Figure 4.49. Comparison showing the change in tip resistance between “Hard” NE corner and “Soft” SW corner

150

Conclusions

Based upon the insitu tests performed the following conclusions are drawn:

35. The generalized soil profile from SPT borings is:

· from 0–5 feet Sand;

· from 5–33 feet Sand to Silty Sand;

· from 33–52 feet Silt Clay to Clay Silt; with some shells

· from 52 –60 feet Silty Cemented Sand (Gravely Sand).

36. From the center eastward a hard pan sand layer exists from about 10 to 15 ft.

37. Comparisons between SPT borings using a hollow stem auger vs. a cased hole using an automatic trip hammer revealed little difference in N values.

38. SPT energy measurements gave energy ratios of 90% for an automatic hammer, and only 71% for a safety hammer, when including rod corrections.

39. Comparisons between DMT soundings using three different agencies revealed consistent results with little variation between agencies.

40. PMT measurements between two different agencies revealed substantial differences. These differences are attributed primarily to an oversized friction reducer on the tip, which caused an oversized hole and subsequent near hole disturbance leading to a softer response.

CHAPTER 5 EVALUATION OF TRIAXIAL TESTING AND INSITU TEST CORRELATIONS

Introduction

Engineering science is mainly based on human interpretation and modeling of

Mother Nature physics phenomena. We try to reproduce, through mathematical

equations, our understanding of the process in study. Geotechnical Engineering addresses

a complex and variable civil engineering material: soil. Every soil mechanism we model,

either by limiting equilibrium Mohr-Coulomb theory or deformation based theory,

requires a basic input of soil engineering properties, i.e. unit weight, friction angle,

cohesion, Young’s modulus, Poisson’s ratio, etc. In order to obtain these soil parameters

laboratory tests are necessary.

Unfortunately, laboratory testing requires the collection of high quality undisturbed

sample material, transporting it back to the laboratory, and in many cases in Florida,

requires freezing of cohesionless samples in order to have the appropriate consistency to

set up the lab test. Considering the fact that most construction sites in Florida consist of

sands with very high water table elevation, undisturbed sampling of soil material

becomes difficult task. Therefore the use of insitu testing as a way to estimate soil

properties has become very popular; among these are SPT, CPT, DMT and PMT.

Problem Statement

Historically, engineers have developed many types of correlations and curve fitting

equations for use with the insitu tests, which provide the necessary soil parameters for

engineering design.

151

152

These correlations are highly dependent on site geographic location, specific

material tested, and technical expertise of the operator running the test. The generalized

use of one or another equation disregarding the fact of different conditions for its

application, can lead to erroneous results.

Objectives

Based upon the aforementioned problems, the objectives of this chapter are

41. To evaluate historically-used insitu test correlations with laboratory results data to obtain the desired soil properties parameters.

42. To select the most reliable insitu test and characteristic correlation of better use for this case specific site.

Testing Layout

In order to compare the results of soil characterization from insitu test with triaxial

testing two SPT tests were performed at the site by GEC. This was done in order to

obtain undisturbed samples. Shelby tubes were taken at depths ranging from 2 to 55 feet.

The location of the SPT under study are shown in Figure 5.1, the tests are denoted as SPT

GEC –1 and 2. SPT GEC –1 is located on the “hard” side of the site; while SPT GEC –2

is located in the “soft” side

GEC-2

Figure 5.1. Location of SPT testing for ext

153

GEC-1

raction of Shelby tubes

154

SPT Correlations

A series of different correlations relating internal friction angle vs. SPT blow

counts, N-value, has been plotted. Some of these correlations consider possible

confinement of the sample by using “overburden-corrected” N-values, and therefore are

directly related with sample position in the ground profile. The samples taken for triaxial

laboratory testing were from 7, 17, 35, 55 ft depths. Those correlations with confinement-

degree dependence are marked accordingly by (depth); e.g. (7 feet). A soil unit weight

was assumed to be 120 pcf, and the water table elevation was assumed as 2-ft below the

ground surface.

The equation used for overburden correction is as follows:

tsfC oo

N'

' ,20log77.0 σσ

=

The SPT based correlations used were:

Bowles (7’ or 45’): 2/1'

55 )(2825o

Nσ

φ +=

Bowles 1 : φ = (18N70)0.5+15

Bowles 2 : φ=0.36N70+27

Bowles 3 : φ= 4.5N70+20

See, Bowles (1996).

Kulhawy (1990) :

34.0

1-

log3.202.12tan

+=

a

oP

Nσ

φ

155

Hatanaka and Uchida (1996): 5.0'

60)60(1)60(1 ,)(4.1520

=++=

a

vo

p

NwithNN

σφ

Peck et al., (1974) using uncorrected N-values as used in FL-PIER

Ne *0147.0*6034.27881.53 −−=φ

Geotechnique: φ=10 logN + 27

As shown in Fig. 5.2, not all correlations plotted provided reliable information. For

example, those given by Hatanaka & Uchida (1996), or the Bowles, (1996) correlations

were quite insensitive to N-values; i.e., a narrow range of φ-values over a wide range of

N-values. In other cases, results went extremely above expected values, as Kulhawy

(1990), or were similar to other correlation, as with Bowles 1 and Bowles 2 expressions.

SPT Correlations for N vs F

0.005.00

10.0015.0020.0025.0030.0035.0040.0045.0050.0055.0060.0065.0070.0075.0080.0085.00

0 5 10 15 20 25 30 35 40 45 50 55 60

Blow Counts, N

Fric

tion

Ang

le, F

Bowles (7')Bowles (45')Kulhawy (7')Kulhawy (45')Insitu2001 (7')Insitu2001 (45')Bowles 1Bowles 2Bowles 3PeckGeotechnique

Figure 5.2. Different trends plotted by the use of correlations interpreting N values as

Friction Angle (φ) of the soil

We limited the analysis to those correlations shown in Fig. 5.3. All seven-

laboratory results were plotted in this chart, two of them provided by the FDOT Lab. For

156

laboratory test results see Table 5.1. The correlation of Peck et al., (1974) used in FPIER

software, and therefore widely used by consulting firms for this type of approach, falls

below the plotted points, showing a considerable conservative analysis. For these data,

the Geotechnique expression fits very closely to our data, much better than Kulhawy and

Mayne (1990) expression, which although plots close to our data distribution, it has very

high values and just applicable to samples at 45 ft depth.

SPT Correlations for N vs F

0

5

10

15

20

25

30

35

40

45

50

55

60

65

0 5 10 15 20 25 30 35 40 45 50 55 60

Blow Counts, N

Fric

tion

Ang

le, F

Kulhawy (45')Bowles 1Bowles 3PeckGeotechnique

UF Results FDOT Results

Figure 5.3. Best-fit NSPT correlations for triaxial laboratory results

The data reduction approach by the University of Florida Lab assumes all the shear

resistance developed in the sample is due to internal friction and does not consider

cohesion; i.e., a c=0 condition. Consequently, this assumption for the cohesionless soils

tests results in higher values of friction angle, φ.

SPT vs. Cohesion

The FDOT-SMO lab used 3 different confining pressures for samples from a single

Shelby tube (boring 2). Consequently, a failure envelope tangent to the Mohr’s circles

gave results were closer to a clayey soil than a sandy soil, with a cohesion of 1435 psf,

157

and a low effective friction angle of 12°. Data obtained from FDOT labs were plotted in

Fig 5.4 , with correlations relating Cohesion with SPT blow counts, N-value,

The correlations used were:

Sowers (1979): NS tsfu 04.0)( =

Bowles (1996): NS tsfu 0625.0)( =

As shown, these correlations are quite conservative and greatly underestimate

cohesion values.

SPT Values Correlations

0

200

400

600

800

1000

1200

1400

1600

1800

0 2 4 6 8 10 12 14

Blow Count, N

Coh

esio

n (p

sf)

SowersBowles

Figure 5.4. Most suitable correlations for determine cohesion when compare with triaxial

results

Table 5.1. Triaxial test results. SPT 1 “hard” area on site, SPT 2 “soft” area on site BoringTriaxial Test 1 FDOT 1 Test 2 Test 3 Test 4 FDOT 2 Test 5Depth (ft) 3 36 55 7 17 36 56N-value 13 5 16 10 9 10 14N-correct 16 6 20 12 11 12 17F (°) 46 Clay 40 39 45 Clay 43c (psf) 0 1435 0 0 0 1688 0

SPT -1 SPT -2

158

CPT and DMT Discussion

Laboratory friction angles (φ) in this case, were also compared with some estimated

values from other insitu tests; specifically, CPT and DMT.

Table 5.2 gives a general idea of the nature of the soil surrounding the two SPT

borings from which the samples were extracted. The values of friction angle shown are

based on the interpretation performed by CONEPLOT, software develop by University of

British Columbia, Vancouver, Canada, using correlations developed by Campanella

(1983).

Table 5.2. General friction angle at UCF sit based on CPT correlations. SPT-2 “soft” area, SPT-1 “hard” area

Depth (ft) qc (tsf) CPT, f (°) Campanella

f (°) Triaxial

SPT

CPT 019 2 30 45 -UF cpt 3 7 60 43 39SW corner 18 42 39 45

36 60 37 Clay56 100 39 43

CPT 213 2 33 47 -Bartow cpt3 7 50 43 39SW corner 18 50 39 45

36 70 35 Clay56 100 39 43

UCF 2 80 47 46UF cpt4 7 140 47 -SE corner 18 80 41 -

36 25 Clay Clay56 100 39 40

UCF 214 2 100 47 46Bartow cpt4 7 160 47 -SE Corner 18 70 41 -

36 10 Clay Clay56 100 39 40

UCF 6 2 54 47 46South Center 7 54 43 39

18 36 39 4536 20 31 Clay56 100 39 40-43

SP

T 1

SP

T 2

In-b

etw

een

159

Due to the fact that the comparison of the Friction angle in Table 5.2 was consider

too general, a narrower approach was considered. For a better comparison only the

reduced data from the test in the close vicinity of the SPT’s was considered.

Friction angle, Insitu Estimations vs. Measured

at "Hard" area of site

0

5

10

15

20

25

30

35

40

45

50

2 7 18 36 56

Depth (ft)

Fric

tion

angl

e, F

(°)

CPTDMTMeasured

Figure 5.5. Friction angle comparison; insitu testing vs. measured (Triaxial) at “Hard”

area of site (SPT-1)

Friction Angle, Insitu Estimations vs. Measured

at "Soft" area of site

0

5

10

15

20

25

30

35

40

45

50

2 7 18 36 56

Depth (ft)

Fric

tion

Ang

le, F

(°)

CPTDMTMeasured

Figure 5.6. Friction angle comparison; insitu testing vs. measured (Triaxial) at “Soft”

area of site (SPT-2)

160

Table 5.3 presents values obtained for the comparison between the results from

triaxial testing and CPT, DMT in areas located in the immediate vicinity of SPT tests.

Table 5.3. Summary of comparison between Triaxial testing , CPT and DMT CPT Depth (ft) CPT, f (°)

Campanella

DMT, f (°) f (°)

Triaxial

SPT DMT

2 45 42 -7 43 43 3918 39 42 4536 37 36 Clay56 39 - 432 47 43 467 47 40 -18 41 39 -36 Clay Clay Clay56 39 - 40 U

F D

MT

1

SPT

1SP

T 2

UF

DM

T 2

CPT

019

Uf c

pt3

SW C

orne

r

UC

F 21

4SM

O c

pt4

SE C

orne

r

The information collected shows a general agreement of the values measured vs.

the ones collected by CPT and DMT, with the exception of the case of the SPT –2 at

depth 36 feet. The CPT and DMT data indicate the existence of sand to this depth, but

measured values from triaxial testing indicate the existence of Clay. A further analysis of

the reduced data collected by DMT and CPT indicate the existence of thin layers of sand

within the large layer of silty clay, which is in concert with the laboratory results. Fig 5.7

is a profile of the soil on the vicinity of the SPT’s based on the previous compared

information.

161

GWT 1.5 feet

Surface

18

GEC -2SPT

GEC -1SPT

NDepth(feet)

19

35

37

55

57

24

35

37

55

57

16

12

9

11

11

64

1914

7

SAND

SILTY SAND

SILTY CLAY W/ SHELLS

FRAGMENTS OF SAND

END OF PREVIOUSINVESTIGATION

60 feet

END OF BORING200 feet

UF Test 1

FDOT

UF Test 2UF Test 5

FDOT

UF Test 4

WITH BROKEN SHELLS

SILTY SAND

SAND

SILTY CLAY W/ SHELLS

60 feet

END OF PREVIOUSINVESTIGATION

130

SILTY CEMENTED

UCF Site Shelby tubes location

SILTY CLAY

SILTY CLAY

6

8

18

10UF Test 3

Figure 5.7. Soil profile base on information collected by CPT ,DMT, SPT and Triaxial

testing

Figures 5.8 and 5.9 show a graphical comparison of the data collected to elaborate

soil profile shown in figure 5.7. Comparison of the soil properties values measured at

laboratory vs. insitu testing show relative agreement. The reduced values obtained from

SPT were found using correlations from Kulhawy(1990) and Geotechnique (2000).

• Comparison between insitu testing performed in the East side of the site, show apparent difference between φ, results from CPT and DMT from depth 0 to 15 feet. There is agreement between comparisons of results from different insitu testing, beyond the 15 feet of depth. Measured value of cohesion from triaxial testing is totally off from the trend line determined by insitu testing results. See Figure 4.8

• Comparison between insitu testing performed in the West side of the site, show strong similitude fron0 to 34 feet. Both SPT correlations fail to characterize the clay layer beyond this point. DMT and CPT values are in concert with triaxial measured result. See Figure 4.9.

0.00

10.00

20.00

30.00

40.00

50.00

60.00

20 30 40 50

φ , Degree

Dep

th (f

eet)

CPT DMT SPT Ku SPT Geo

Triaxial 3'

Triaxial 55'

0 .0 0

1 0 .0 0

2 0 .0 0

3 0 .0 0

4 0 .0 0

5 0 .0 0

6 0 .0 0

0 500 1000 1500 2000 2500 3000

Su (psf)

DMT CPT SPT Sow SPT Bow

Triaxial 36'

162

Figure 5.8. Comparison of insitu testing CPT, DMT, SPT vs. Triaxial testing results in the East side of site

0.00

10.00

20.00

30.00

40.00

50.00

60.00

20 30 40 50

φ, Angel of Friction

Dep

th(fe

et)

DMT CPTSPT-Ku SPT Geo

0 .0 0

1 0 .0 0

2 0 .0 0

3 0 .0 0

4 0 .0 0

5 0 .0 0

6 0 .0 0

0 1000 2000 3000

Su (psf)

CPT DMT SPT Sow SPT Bow

Triaxial 36'

Triaxial 7'

Triaxial 17'

Triaxial 56'

163

Figure 5.9. Comparison of insitu testing CPT, DMT, SPT vs. Triaxial testing results in the West side of site

CHAPTER 6 PMT TESTING AND CALIBRATION

Friction Reducer Evaluation

To evaluate the friction reducer ring effects, two tips, one with and one without a

friction reducer ring, were tested at two Gainesville sites (cohesive and a cohesionless).

• Lake Alice. A site where UF has performed considerable insitu testing in the last two years as part of the instruction course “CEG-5250 Insitu Measurement of Soil Properties” offered by the University to graduate students every Spring. This site is considered cohesive, mixed with sand and silts. See Figure 6.1 for soil profile.

• The Archer Road Landfill. This cohesionless site has previously been tested by PhD graduates, Brian Anderson and Landy Rahelison

The evaluation of the friction ring effect required three critical points.

• Uniform site conditions or soil properties. Test performed in a cohesive or in a cohesionless soil.

• Same test and calibration routine.

• Same data reduction procedure.

Test Comparison (Friction Reducer Ring vs. No Friction Reducer Ring)

Comparison at Lake Alice

Characteristics of the site. (cohesive soil) clays

This site is considered cohesive, mixed with sand and silts. The objective was to

perform comparison tests at the same depth using the two different cone tips, with and

without a friction reducer ring. The tests were performed at depths 5, 10, 20 and 40 feet

on two separate boreholes close enough for comparison yet located a safe distance from

each other with the intention of avoiding disturbance. See Figure 6.2 to observe location

of the boring in the area of study. The tests were compared with results of several tests

164

165

previously performed in the area by UF students. The soil profile at the site is shown in

the Figure 6.1.

Figure 6.1. Sketch of general soil profile at Lake Alice. Highlighted appear the main clay

layer tested on this research.

The soil profile shown in Figure 6.1, is based on the interpretation of the data

obtained from the reduction of the ECPT test. The relative location of the PMT and

ECPT tests used for this research are shown in Figure 6.2. The reduced data are shown in

the appendix B.

166

Figure 6.2. Sketch of research site at Lake Alice showing relative location of new PMT

testing (denoted NR and WR) vs. previous PMT-2. On the sketch also appear location of CPT test used as reference for soil profile

167

PMT test results - Lake Alice location

Membrane rupture at the Lake Alice field test site resulted in the use of a different

membrane for each test with and without the friction reducer. This situation implied the

use of a new calibration and different membrane each time the test was performed. The

need of using a different membrane for every test simulates the actual conditions at the

UCF site. This is, two different agencies performing tests on the same type of soil. The

simulation is only different from our original conditions at the UCF site because the same

operator was performing both tests. See Chapter 3, Insitu Tests Methods, PMT page 18,

Factors Affecting Results, in this report.

The following Figures 6.3 to 6.6 show the corrected curves Pressure vs. Volume

from pressuremeter test at depths of 5, 10, 20 and 40 feet.

Figure 6.3. Lake Alice comparison of different friction reducer at depth 5 feet

168



169


A comparative examination of these PMT results show

1. The limit pressure, PL, is slightly higher for the ring on tip at 5, 10, and 40 ft. depths. This could be attributed to the oversized ring creating a greater lateral stress consequently strengthening the clay.

2. The initial P-V curve is “S”shaped for the ring on tip at 5,10,and 20 ft. depths. Apparently the ring oversizes the hole and more volume is required for contact between probe and borehole wall. At 40 ft. sufficient overburden stress “closes” the hole lessening the volume required for contact.

The data reduction from the tests shows that only at the depth of 20 feet below

grade, is an obvious discrepancy observable between the test results using the two

different tips that may be related to with the incorrect used of the PMT.

The results of the comparison data between the two different tips do not indicate

significant differences between the two tests. This result indicates that the friction reducer

ring has no significant effect in cohesive soils. However, no difference eliminates the

reducer ring as being the culprit for the difference between UF and SMO PMT tests at the

FDOT- UCF site.

170

Data reduction method

Another point of importance in the analysis of the test results was the comparison

of the values of the PENCEL Pressuremeter Modulus obtained in our research program

tests with the ones obtained by UF (Insitu Class) Spring 2003 and in Spring 2002. The

results at Lake Alice allow a comparison between hand and spread-sheet data reduction

methods. The reduction of the data from FDOT-UCF Site and Comparison of the two

cone tips at Lake Alice has been carried out with the use of Anderson’s

spreadsheets(2003). A comparison of computer solution with a hand solution was needed

in order to check the values obtained through spreadsheets. Results of previous PMT-2

performed by UF Class Spring 2002 using hand-reduction methods are shown in fig 6.7

and 6.8.

As illustrated in Table 6.1, the results of the comparison between the excel spread-

sheet and the student’s tests do not indicate notable or significant differences.

Table 6.1. Comparisons of the Ei modulus obtain from research versus back up data from insitu class 2002

Depth (ft)Class2002

No Ring tip Ring tip5 881.7 721.9 964.7

10 2071.9 1950 1892

Ei PMT PENCEL (psi)Research

At the depth of 5 and 10 feet little or no difference was found between the two

methods used to obtain the pressuremeter modulus. The results shown in Table 6.1

indicate that the offset of the values obtained through the use of computer generated best

fit curves are located within a reasonable range of error in reference to the hand generated

curves. Please notice that the little changes in values of pressuremeter modulus, have no

effect for design purposes.

Pl = 50 psi

171

Figure 6.7. Copy of hand reduced data, from pressuremeter test performed by insitu class 2002 at Lake Alice , depth 1,5 m

Pl = 110 psi

172

Figure 6.8. Copy of hand reduced data, from pressuremeter test performed by insitu class 2002 at Lake Alice , depth 2,5 m

173

Comparison at Archer Landfill research site

Characteristics of the site (cohesionless soil) sands

For several years the Archer Landfill has been used by UF to conduct insitu testing

research. The landfill site is essentially forty feet of sand overlying limerock. A sketch of

the site general profile is shown in Figure 6.9.

The objective again was to perform comparison tests at depths previously studied,

using the two different cone tips; i.e., with and without a friction reducer ring. The tests

were performed at depths of 5, 10, and 20 feet in two separate boreholes close enough for

comparison yet located sufficiently far apart to avoid influence from the results of the

adjacent borehole location.

A sketch of the approximate location of the research site is shown in Figure 6.10.

Additional insitu test data from the CPT can be found in the Appendix B.

UF CPT REPORT FOR ARCHER LANDFILLCPTAL-4

SILTY SAND TO SANDY SILT

SAND TO SILTY SAND

SAND

14

21

35

42

Depth(feet)

10 (Feet) UF RESEARCH


42 feet

END OF BORING


SILTY SAND TO SANDY SILT

Figure 6.9. Archer Landfill soil profile based CPT data from previous research

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Test conditions and results from work at Lake Alice location

In the case of the Archer testing site the circumstances were propitious for utilizing

the equipment belonging to UF and FDOT, which simulates the actual conditions at the

FDOT-UCF site; i.e., use of a different probe and operator for each test with and without

the friction reducer. This situation implied the use of a new calibration and different

membrane each time the test was performed.

Due to the poor quality and variability in the results of the data collected using the

ring tip, it was necessary to substitute these data with those collected by Anderson (2001)

in previous research. The 20 feet mark was fixed as the limit depth of testing, due to the

lack of data at greater depths, from the previous report.

Figure 6.10. Location of research site at Archer landfill

Figures 6.11 to figure 6.13 show the comparisons of the corrected PENCEL

Pressuremeter curves.

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Comparison- Archer Ld. - 5ft

-10

0

10

20

30

40

50

60

70

-10 10 30 50 70 90 1

Volume (cc)

Pres

sure

(psi

)

10

UFData(Ring-JBA) FDOTData(NoRing)

Figure 6.11. Archer Landfill comparison of different friction reducer at depth 5 feet


-20

0

20

40

60

80

100

-5 15 35 55 75 95 115

Volume (cc)

Pres

sure

(psi

)



176


-50

0

50

100

150

200

250

300

350

-20 0 20 40 60 80 100 120

Volume (cc)

Pres

sure

(psi

)



Quite differently from the Lake Alice research site, the results of the pressuremeter

test in the cohesionless soil diverge between the two types of probes, with or without

ring. In order to clarify these results more data were added to the comparison. The data

available from these research, shown at Figures 6.14 to 6.16, have most of the

information based on results using the no ring probe from depth 5 to 20 feet, and only one

additional test using the ring probe.

177

Figure 6.14. Archer Landfill, comparison of all data available at depth 5 feet


178


Based on the information collected in the conducted research and data shown on

Figures 6.11 to 6.16, it is concluded that

43. The PMT results of the test seems to agree up to the depth of 10 feet but show variability bellow 20 feet. See Table 6.2.

44. There is discrepancy between the values of limit pressures, developed by the ring probe. Sometimes these values are significantly higher or lower than the no ring probe. More data are needed in order to drawn conclusions on this mater.

45. The value of the limit pressures developed by the no ring probe seems to be on a stable range. These value increase proportionally to depth of research.

46. A comparison of the moduli values in Table 6.2 shows a little discrepancy between the values of Initial modulus Ei. This type of difference is expected in the initial part of the loading curve and didn’t represent a point of concern, if the values are kept in the same order.

47. For the two shallower depths, the values of unload-reload modulus EUR, are quite similar for both tips. However, for the deeper depths it shows disagreement.

The Table 6.2 shows a comparison of the pressuremeter Initial Modulus (Ei) and

Unload-reload Modulus (EUR) obtained by Anderson (2001) at Archer Landfill versus the

new values of Ei and EUR obtained in this research. As can be seen in Table 6.2, in

179

general there is a similarity between the values of pressuremeter modulus obtained for

this investigation, with the ring probe results of the previous Anderson (2001) work.

Table 6.2. Comparison of the pressuremeter initial modulus (Ei) and unload reload modulus (EUR) at Archer Landfill site

Depth (ft)Research No

Ring tipB.Anderson Ring on tip

Research No Ring tip

B.Anderson Ring on tip

5 512 591 6843 525410 1499 1074 10419 941720 5723 3719 97977 21151

Eur PMT Pencel (psi)Ei PMT Pencel (psi)

The result of the comparison of all the data available shown in Figures 6.14 to 6.16,

indicates that the No Ring probe follows a visible trend. In order to give a final

conclusion on the behavior of the ringed probe, more testing will be necessary.

Conclusions

Analysis of results

The comparison of two different probes (ring and no-ring on tip) at cohesive soils

shows no apparent differences between them.

The comparison of two different probes (ring and no ring on tip) at cohesionless

soils shows total discrepancy between them at depths greater than 10 feet. More

investigation is already planed in order to solve or find the causes of these discrepancies

The accumulated experience performing the test is not enough to clearly define the

possible causes of agreement or disagreement in each case, but a follow up of the

procedures defined and submitted in this report (see calibration and Testing of PMT,

section at Chapter 3) will help to narrow down the differences between the two tests.

The results obtained with the use of Anderson’s (2001) spreadsheet shows

accordance with reduced data performed by hand. The results shown in Table 6.1 indicate

that the offset of the values obtained through the use of computer generated best fit

180

curves are located on a reasonable range of error in reference to the hand generated

curves.

Suggested future work

Perform additional series of tests at the Archer Landfill research site, using the

Ring tip, taking special care in the penetration of the layers near and below 20 feet.

Perform additional series of tests at the Lake Alice site, in order to look for

reliability in the test. This is to find out if the test is reproducible or not.

CHAPTER 7 CONCLUSIONS AND RECOMENDATIONS

Conclusions

FDOT-UCF Research Site

Based on the comparison of the entire data collected trough the different insitu tests

and with the use of the GMS software a general soil profile of the site was drawn. The

Figure 7.1 shows a cross section of the site.

Figure 7.1. FDOT-UCF site soil profile along the SE to NW edge

The following conclusions are drawn, as a result of the analysis of the information

accumulated:

• From 0-5 feet sand

• From 5-33 feet as shown on the profile on the NW side there are successive layers of sand interspersed with silty sand layers. Contrary to the SE side of the site where the layer is mostly formed by sand.

• From 33-48 feet Clayey sands to clayey silt and some shell.

181

182

• From 48-52 feet silty sand.

• From 52-60 feet Shelly silty cemented sand (gravely sand).

The existence of a hardpan layer from the 8 to 15 feet of depth was located on the

center eastward of the site. This information was corroborated by the information obtain

with SPT, CPT and DMT.

Water level was found as high as 1.5 feet below surface.

The analysis of the data, collected with the use of the CPT, shows little variation of

soil profile, along the entire research site. There is a relative uniformity at the site.

Comparison of the data collected with the DMT and CPT, shows the justified

confidence that engineers are having in the reliance of these insitu tests. The comparison

between different agencies, revealed consistent results.

The comparisons between SPT borings using different operators, drilling

techniques and automatic hammer vs. safety hammer, shows that the N values follow a

defined trend, with little difference between them.

The comparison of the data collected from the geophysical methods with the data

collected through the use of traditional insitu testing shows total agreement. The use of

back up data from CPT or SPT was of vital importance for accuracy of results and the

interpretation of the data.

Triaxial Testing and Correlations

SPT vs φ angle

For the analyzed data, the Geotechnique 2000 expression fits very closely to the

information obtained with the triaxial testing program in order to determine φ angle.

183

SPT vs cohesion

Sowers (1979) and Bowles (1996) were the used correlations for this research and

are shown to be quite conservative and greatly underestimate cohesion values.

SPT, CPT and DMT vs triaxial testing

The information collected shows a general agreement of the values measured vs.

the ones collected by CPT and DMT. There is general agreement on the predictions

obtain with the use of the three insitu test up to 35 feet, but data show slightly dispersion

below this depth. Cohesion values from CPT and DMT are in concert with values

measured with triaxial testing.

PMT Results

The comparison of different PMT probes, at the FDOT-UCF reveals substantial

differences. A program of testing was implemented by UF and FDOT in order to solve

these divergences.

The testing program for solving the PMT variability, help to create new regulations

and improving of technique during performance of the test.

The comparison of two different probes (ring and no-ring on tip) at cohesive soils

shows no apparent differences between them.

The comparison of two different probes (ring and no ring on tip) at cohesionless

soils shows total discrepancy between them when depth is increased beyond 10 feet.

More investigation is already planed in order to solve or reveal the causes of these

discrepancies.

Comparison of data reduced with the computer generated correction curves with

results reduced by hand shows agreement. The results indicate that the offset of the

184

values obtained through the use of computer generated best fit curves are located on a

reasonable range of error in reference to the hand generated curves.

Recommendations

The discrepancies found between the PMT results using different probes must be

kept under study. Special attention must be given to the ringed probe in future

investigation.

The new recommendations on procedure for the use of the pressuremeter must be

edited together with the findings on the PMT testing program in order to create a standard

procedure, for this type of test.

APPENDIX A STANDARD PENETRATION TEST (SPT) BORING LOGS

The following figures show the boring logs obtained from the SPT performed at the

site. The boring logs give a characterization of the soil profile of the site based on data

interpretation of retrieved samples and “N” values versus depth.

185

APPENDIX B PMT BACK UP DATA FOR LAKE ALICE AND ARCHER LANDFILL.

The following figures show additional insitu test data performed at the respective

research sites. These CPT boring logs give characterization of the soil profile of the

nearby area were the PMT test were performed. The interpretation of the data collected is

performed based on software developed by University of British Columbia. (Coneplot).

208

209

Archer Landfill CPT.

Lake Alice CPT.

211

APPENDIX C BACK UP DATA FOR TRIAXIAL TEST

The following is a compilation of the data collected during the triaxial testing

program performed at UF in order to determine soil properties from retrieved undisturbed

samples. The information presented only shows the final results. The actual testing logs

are attached to the electronic file, submitted with the report.

213

214

Test ID : No 1 Date tested: 12/11/2002Borehole ID : No 1 Date Sampled: 10/1/2002Shelby Tube ID: No 1 Note: Tube depth 2 -4 feetDeth testedSample Descriptiom:Diameter of Sample: 2.838"Sample height: 12.383 cm 4.87"Test Type: CD

Sigma3 55 psi

Phi angle 36Deviatoric Stress 155 psi

Sample Dark Brown Silty Sand with some large roots.

Only 6" recovery from the shelby tube

FDOT- UCF #1 CD BH 1 (6 -8 feet)

0

5

10

15

20

25

30

-0.02 0 0.02 0.04 0.06 0.08 0.1 0.12

Strain

Dev

Str

ess

(psi

)

215

Test ID : No 2 Date tested: 12/13/2002Borehole ID : No 1 Date Sampled: 10/1/2002Shelby Tube ID: No 4 Note: Tube depth 55.5 -58 feetDeth tested 57 - 57.5 feetSample Descriptiom:Diameter of Sample: 2.845"Sample height: 15.667cm 6.16"Test Type: CU

Sigma3 30 psi

Phi angle 36Deviatoric Stress 300 psi

Silty Clayey Sand with cemented fragments and shell

FDOT - UCF Test 2 CU BH 1 (55.5 -56.5 feet)

0

5

10

15

20

25

30

35

40

45

-0.02 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16

Strain

Dev

Stre

ss (p

si)

216

Test ID : No 3 Date tested: 12/16/2002Borehole ID : No 1 Date Sampled: 10/1/2002Shelby Tube ID: No 2 Note: Tube depth 6 - 8 feetDeth tested 7.5 - 8 feetSample Descriptiom:Diameter of Sample: 2.845"Sample height: 15.33cm 6.03"Test Type: CD

Sigma3 55 psi

Phi angle 36Deviatoric Stress 141psi

Light brown Silty Sand.


UCF BH2 Test # 3 CD (6 -8 feet)

0

5

10

15

20

25

0 0.05 0.1 0.15 0.2

Strain

Dev

Stre

ss (p

si)

217

Test ID : No 4 Date tested: 12/17/2002Borehole ID : No 2 Date Sampled: 10/14/2002Shelby Tube ID: No 2 Note: Tube depth 16.5 - 19 feetDeth tested 18.5 - 19 feetSample Descriptiom:Diameter of Sample: 2.863Sample height: 15.65 6.16"Test Type: CD

Sigma3 61 psiu 50psiPhi angle 36Deviatoric Stress 346psi


UCF Test #4 cd BH 2 (18 -19 feet)

0

10

20

30

40

50

60

-0.02 0 0.02 0.04 0.06 0.08

Strain

Dev

Stre

ss (p

si)

218

Test ID : No 5 Date tested: 12/19/2002Borehole ID : No 2 Date Sampled: 10/14/2002Shelby Tube ID: No 4 Note: Tube depth 54.5 - 57 feetDeth tested 56 - 56.5 feetSample Descriptiom:Diameter of Sample: 2.809Sample height: 15.03cm 5.91"Test Type: CU

Sigma3 80psiu 50psiPhi angle 36Deviatoric Stress 346psi


Silty Clayey Sand with cemented fragments and shell

UCF #5 cu BH 2 (55.5 - 57 feet)

0

5

10

15

20

25

30

-0.05 0 0.05 0.1 0.15 0.2

Strain

Dev

Stre

ss (p

si)

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BIOGRAPHICAL SKETCH

The author was born in “La Habana,” Cuba, on January 21, 1972. He is the first of

two children by his parents Evelio N. Horta and Zoila Tirado. The author attended high

school in Havana, until 1989 when he was situated into the SMM, Mandatory Military

Service. One year later the author returned to attend the ISPJAE, Superior Polytechnic

Institute at Havana for his bachelor’s degree in civil engineering. In 1995 he graduated

and began to work in a construction design company in Havana, Cuba, taking part in the

development of more than seven tourist resorts along the island. By the year 2000 he was

already in charge of several projects and was the head of the civil team in his office.

In the summer of 2001, the author moved to West Palm Beach, Florida, and started

to work as a staff engineer for Ardaman & Associates, Inc., a geotechnical engineering

company. He started his master’s degree in geotechnical engineering at the University of

Florida in the spring of 2002. The author finished in December of 2003.

222

site preparation for a deep foundation test site, at

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