geophysical manual · ultraseismic, seismic wave reflection, transient force vibration, parallel...

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GEOHAZARDS FORUM, August 2-3, 2006, Lexington, Kentucky

GEOPHYSICAL MANUALGEOPHYSICAL MANUALA Practical Engineering Solution for Highway Related A Practical Engineering Solution for Highway Related

ProblemsProblems

By:Kanaan Hanna

Geotechnical Engineer

Khamis HaramyGeotechnical Engineer

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Abandoned Mine VoidsDetection

Presentation FocusPresentation Focus

Geophysical Manual

Part IGeophysical

Workshop

Part II Part II

HIGHHIGH--RESOLUTION GEOPHYSICAL RESOLUTION GEOPHYSICAL TECHNOLOGIES FOR TRANSPORTATIONTECHNOLOGIES FOR TRANSPORTATION

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Part I & II Part I & II –– BackgroundBackground

Why geophysical imaging technologies have not been fully utilized in engineering

investigations

• Highway engineers are using geophysics,but… Not much confidence

• Blackbox stigme• Processing complexity• Selecting EXPERIENCED geophysical contractor

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What can geophysics do for Highway Engineer

• Geophysics Engineering Benefit– Reduce cost– Less environmental impact– Better site characterization– Safer and more economical design– Accurate bids– Fewer claims

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FHWA – CFLHD Initiatives In cooperation with Blackhawk developed two documents…

• Geophysical Manual– A practical engineering solutions for highway related problems

Designed on solving engineering problems using various geophysical methods and techniques

• Geophysical Workshop– Increase confidence and familiarize Highway Engineers with

geophysical technologies for transportation projectsDesigned on using various geophysical methods and techniques

for solving engineering problems

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Part I – Geophysical Manual

An Overview of the Geophysical Manual

ASTM Standard D6429-99Standard Guide for Selecting Surface

Geophysical Methods

ASTM Standard D420-98 (2003)Standard Guide to Site

Characterization for Engineering Design, and Construction Purposes

ASTM References

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Chapter 1 Introduction• Purpose• Background• Evaluation of Appropriate Geophysical

Methods (Table 1)

Chapter 2 through 10 in two parts• Part I Engineering Applications – Chapter 2 through 7• Part II Detailed/Theory – Chapter 8 through 10

Bibliography for Part I and IIGlossary – Definitions of terms

Document Organization


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Part I – Geophysical ManualEngineering Problem Application Geophysical/NDT Solutions

Unknown Depth of Foundations

Sonic Echo/Impulse Response, Bending wave, Ultraseismic, Seismic Wave Reflection,

Transient Force Vibration, Parallel Seismic, Induction Field, Borehole logging, Dynamic

Foundation Response, Borehole Radar, Borehole Seismic

Integrity Testing of Foundations and Structures

Crosshole Sonic Logging, Crosshole Sonic Logging Tomography, Gamma-Gamma Density

Logging, Singlehole Sonic Logging, Sonic Echo/Impulse Response, Ultraseismic Profiling, Ultrasonic Pulse Velocity, Impact Echo, Ground Penetrating Radar, Spectral Analysis of Surface

Waves, Acoustic Emissions, Radiography

Rebar Quality and Bonding Half-cell Potential, Linear Polarization

Resistance, Galvanostatic Pulse Technique, Electrochemical Noise, Acoustic Emissions,

Magnetic Field Disturbance

CHAPTER 2 -

BRIDGE SYSTEM SUBSTRUCTURE

Foundation Scour Time Domain Reflectometry, Parallel Seismic, Ground Penetrating Radar, Continuous Seismic

Reflection Profiling, Fathometer

Bridge Deck Stability New Decks

Baseline Assessment

CHAPTER 3 -

BRIDGE SYSTEM SUPERSTRUCTURE Existing Decks

Vibration Monitoring, Ground Penetrating Radar, Electromagnetic, Impact Echo, Spectral

Analysis of Surface Waves and Ultrasonic Surface Waves Methods, Half-Cell Corrosion

Potential Mapping, Infrared Thermography

QA/QC Of New Pavements Existing Pavements CHAPTER 4 -

PAVEMENTS Transportation / Geotechnical

Methods

GPR, Impact Echo, Spectral Analysis of Surface Waves, Ultra Sonic Surface Wave (USW), Multichannel Analysis of Surface Waves

(MASW)

Mapping Voids, Sinkholes, Abandoned Mines, and Other

Cavities

Gravity, GPR, Resistivity , Seismic Refraction, Seismic Reflection, Rayleigh Waves Recorded with a Common Offset Array, Cross-borehole

Seismic Tomography CHAPTER 5 -

ROADWAY

SUBSIDENCE Roadbed Clay Problems

Conductivity Measurements, Resistivity Measurements, Time Domain Electromagnetic

Soundings, Induced Polarization

Mapping Bedrock, Lithologies, Sand & Gravel

Deposits, Groundwater Surface, and Flow

Ground Penetrating Radar, Seismic Refraction, Compressional and Shear Wave Reflection, Resistivity, Time Domain Electromagnetic,

Conductivity Measurements, Spectral Analysis of Surface Waves, Gravity, Very Low Frequency Electromagnetic, Borehole Televiewer, Induced

Polarization, Borehole Gamma and HydroPhysical Logging, Nuclear Magnetic Resonance, Self Potential, Electroseismic

Determining Engineering Properties and Rippability of

Soil and Rock

Seismic Refraction, Nuclear Magnetic Resonance, Ground Penetrating Radar, Spectral

Analysis of Surface Waves, Suspension Logging, Full Waveform Sonic Logging, Crosshole Shear

CHAPTER 6 -

SUBSURFACE CHARATERIZATION

Utility Locator, Detecting Underground Storage Tank,

UXO and Contaminant Plums

Magnetic, Electromagnetic, Ground Penetrating Radar, Acoustic Pipe Tracer, Metal Detectors,

resistivity, Induced Polarization, Refraction

CHAPTER 7 -

VIBRATION MEASUREMENTS

Vibration Caused By Traffic, Construction, and Blasting

Vibration Monitoring

Table 1 Document

Organization

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Geophysical Manual Available Formats

• Hard copy – one volume, 742 pages, with 400 figures

• Adobe Acrobat File (pdf) on CD (available from Blackhawk)

• Online at the FHWA, CFLHD local site @ the following url:

http://www.cflhd.gov/geotechnical


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Navigation through the web site


SplashSite

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SOLUTION MATRIXSOLUTION MATRIX

PART IIGEOPHYSICAL METHODS/THEORIS

PART IIGEOPHYSICAL METHODS/THEORIS

The web Manual is designed with a Solution Matrix to guide the user for specific applications

PART IENGINEERING APPLICATIONS

PART IENGINEERING APPLICATIONS


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PART I – Problem/Application


ENGINEERING APPLICATIONSENGINEERING APPLICATIONS

BRIDGEBRIDGE

PAVEMENTSPAVEMENTS

ROADWAYSUBSIDANCEROADWAY

SUBSIDANCEVIBRATION

MONITORINGVIBRATION

MONITORING

VoidsVoids ClayClay

SinkholesSinkholes

Abandoned Mines

Abandoned Mines

CavitiesCavities

SUBSURFACECHARACTARIZATION

SUBSURFACECHARACTARIZATION

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Voids DetectionVoids Detection


Gravity

GPR

Resistivity

Cross-hole Seismic Tomography

Seismic Refraction

Shear-wave Seismic Reflection

Rayleigh Waves recorded witha Common Offset Array

● Basic Concept…… ● Data Interpretation……

● Data Acquisition…… ● Advantages……

● Data Processing…… ● Limitation……

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PART II – Detailed/Theory

GEOPHYSICAL METHODSGEOPHYSICAL METHODS

GEOPHYSICALQUANTITIES

GEOPHYSICALQUANTITIES

SURFACEMETHODS

SURFACEMETHODS

BOREHOLEMETHODS

BOREHOLEMETHODS


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Part II – Geophysical Workshop

FHWA – CFLHD Initiatives In cooperation with Blackhawk developed two documents…

• Geophysical ManualDesigned on solving engineering problems using various geophysical

methods and techniques• Geophysical Workshop

Designed on using various geophysical methods and techniquesfor solving engineering problems

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Geophysical Summaries

Engineering Benefit

Geophysical ManualFeature Comparison Matrix

Method Briefs

VoidsClay

Seismic ReflectionSeismic Refraction

SASWMASW

Crosshole Seismic

Electrical ResistivityTDEMFDEM

Magnetics

GPR


An Overview ofGeophysics

Case Studies

Choosing a Geophysical Contractor Summary

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Engineering Benefit

Geophysical ManualFeature Comparison Matrix

Method Briefs

VoidsClay

Seismic ReflectionSeismic Refraction

SASWMASW

Crosshole Seismic

Electrical ResistivityTDEMFDEM

Magnetics

GPR


An Overview ofGeophysics

Case Studies

Choosing a Geophysical Contractor Summary

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Method Brief

Basic Principles

Instrumentation

Data Examples

Field Surveys

Limitations

Advantages

Seismic Refraction

Seismic Reflection

Crosshole Seismic

Ground Penetrating Radar

Electrical Resistivity

Electromagnetic (TDEM/FDEM)

Magnetics

SASW / MASW

Geophysical Summary


Methods

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Seismic RefractionTaylor River Road, CO (FHWA, CFLHD)


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Loose-Medium dense silty SAND

Medium dense-Dense silty SANDS with Cobbles, boulders and rock fragments

Granite, moderately weathered

Highly fractured rock, granite/mica schist

300 m/s

500 m/s

600 m/s

700 m/s

800 m/s

900 m/s

1,000 m/s

1,100 m/s

400 m/s

Vel

ocity

Sca

le

Assumed Competent rock

Velocity Scale, m/s

300 1,100Softer Harder

Seismic RefractionData Example: Mapping Bedrock Seismic Refraction Tomography


-2020 10 -10Distance, m

2,700

2,680

2,690

2,695

2,685

Elev

atio

n, m

-15- 5515

Boring

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Tow Vehicle and EM31-3 Array System

GPS

Frequency Domain Electromagnetics (EM)


Geophysical data integrated with GPS dataData acquisition speed ~ 10MPHTotal surveyed area ~ 34 milesField days ~ 4Soil boring performed during and after survey

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Data Profiles provide limited information

EM38

Distance, m

80

40

100

EM31

Con

duct

ivity

, mS/

m

0MM46

EM Data PresentationFrom Physics to Engineering Data

P&P drawings provide optimum information


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GEOPHYSICAL VOID DETECTIONDEMONSTRATIONS

Part III – Abandoned Mine Voids Detection

• Seismic Reflection•P-waves•S-wave

• Cross-hole tomography• Guided waves• RVSP• Sonar mapping

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• Unknown mines,• Inaccurate historical mine maps, or• Incomplete historical mine maps

MSHA Old mine works present major H&S hazards to our nation’s miners…

DOT’s Abandoned mines beneath roadways impact the performance of transportation infrastructure in terms of…• Cost,• Public safety


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Criterion HRPW HRSW XHT GuidedWaves RVSP Sonar

Mapping*

Ability to LocateMine Works/Voids Fair Fair Poor Poor Good n/a

Resolution Poor Poor Poor Very Poor Very Good Excellent

Depth ofInvestigation Good Poor Good Good Good Very Good

AnticipatedRepeatability Good Fair Good Fair Good Very Good

Robustness underVariousGeologic/SurfaceConditions

Fair Poor Fair Fair Good Very Good

Cost High Very High Medium Low Medium Medium

Void Contents Poor Good Poor Poor Good Very Good

*Sonar mapping can only be used in a borehole that has intersected a water-filled void in the mine.

Performance Evaluation of Geophysical Methods


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HRS Data Analysis and InterpretationAnomalous Coal Response from P-wave

Part III – Abandoned Mine Void Detection

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RVSP Data Analysis and InterpretationSeismic Amplitudes from RVSP Profiles along the Target Zone


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RVSP Peak Seismic Amplitudes at Target Zone Overlain on Historical Mine Map


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Void Confirmation through Drilling and Sonar Mapping


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RVSP Application for Planned Development Site, Erie, CO

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• xxx


RVSP Peak Seismic Amplitudes at Target Zone Overlain on Historical Mine Map

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Thank You

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Training Material for Workshop on

Geophysical Methods for Transportation Applications

February 25, 2005

FHWA Resource Center


Case Studies

Engineering Benefit

Summary

Choosing a Geophysical Contractor

Method Briefs

Feature Comparison Matrix

OverviewTable of Contents


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Feature Comparison Matrix

FeatureGeophysical

MethodAdvantages Limitations

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-GPR Shallow voids only

Data recorded quickly and displayed on screen in during field acquisition

Antenna frequency changed quickly to either enhance resolution or penetration

Success is very site specific

Depends on a contrast in dielectric properties between thetarget and host

Any metal features may hinder surveyy

Resistivity Quite successful at imaging large shallow voids

Voids have a high resistivity

Best suited for finding shallow voids, 20 to 30 m depending on geology and void size

A 1 to 2 ratio is necessary for electrode arrays. A 40 ft deepvoid would require an 80 foot electrode spacing, which may not be efficient

Seismic Refraction

Rapid to apply in the field

Seismic refraction records are displayed on the instrument allowing potential fractures to be recognized during the field surve y

This method is indirect as it detects fractures and not voids

Voids may be detected if they are not too far beneath the bedrock

Fractures may not be related to a void and have some other origin

Shear -wave Seismic Reflection

Success depends on the f requency of shear waves in the ground

If high frequencies can be generated, small voids can be detected

Shear wave reflection is labor intensive

Requires extensive processing

Few sources exist for shear wave propagation

Voids, sinkholes,abandoned mines’karst

Crosshole Tomography

Tomograph y provides a high - resolution 2D or 3D volumetric image between two boreholes

Can image the entire length of the borehole

No diminishing returns with depth

Tomography is data intensive

Specialized 3D software is required for true 3D imaging

Artifacts c an be present due to limited ray coverage near image boundaries

Feature Comparison MatrixPart II – Geophysical Workshop

Voids, Clay, Bedrock Depth/Fracture, Faults, Lithology, Sand and Gravel, Utilities, UST, Plumes, UXO

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Penetration

and Resolution

Horizontal Resolution

Dep

th/V

ertic

alR

esol

utio

n

Pen

etra

tion

Ground/Structure Surface

Key Geophysical Concepts – Contrast


High-Resolution GPRVoid Detection

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Part III – Abandoned Mine Voids Detection Methodology A systematic approach – integrating 2-D and/or 3-D geophysical investigations with subsidence/geotechnical engineering evaluation for optimum foundation design…

Geophysics Subsurface Investigation:• Identify old mine works• Identify mine voids

Engineering GeophysicsSubsurface Characterization in terms of:• Subsidence evaluation• Void detection evaluation

Engineering Evaluation

Engineering Analysis:• Geotechnical evaluation• Foundation system evaluation and risk assessment• Engineering decision

geophysical manual · ultraseismic, seismic wave reflection, transient force vibration, parallel...

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