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Soil Mechanics Laboratory

Course Documents

California State Universit , Fullerton

Civil & Environmental Engineering Department



Table of Contents

Page No.

1. Syllabus 1

2. Sieve Analysis 6

3. Hydrometer Analysis 10

4. Specific Gravity Test 14

5. Liquid Limit Test 16

6. Plastic Limit Test 20

7. Classification of Soil 22

8. Compaction Test 28

9. Laboratory Compaction Test 35

10. Constant Head and Falling Head Permeability Test 46

11. Calculation of Seepage Discharge and Seepage Pressure 54

12. Verification of Seepage Through Cofferdam 65

13. Measurement of Shear Strength of Soil with Direct Shear Test 68

14. Measurement of Shear Strength of Soil with Triaxial Test 72

15. UU Triaxial Test 81

16. Slope Stability Analysis 92

17. How Much Did You Learn? 102



California State University, FullertonCollege of Engineering and Computer Science

Civil and Environmental Engineering Department

EGCE 324L SOIL MECHANICS LABORATORYSCH 22037

Spring Semester 2013

Instructor: Santiago Caballero M.C.E.Office: E 308Fax: (657) 278-3916Email: [email protected]

Class Meeting: T 13:00 – 15:45Class Room: EC-063Units: 1

Prerequisite EGCE 324 and ENGL 101Students registered for this course should have completed the prerequisite courses. During thesemester, the department will verify the prerequisite requirements. If any student has completedthe prerequisite course at another school, please submit appropriate documents to thedepartment secretary. Otherwise, their name will be deleted from the class list at any time duringthe semester.

Text Book

Soil Mechanics Laboratory Manual (with disk) by Braja M. Das, 7th Edition, 2009, Oxford

University Press , ISBN 9780195367591

Reference Materials

· Handouts, website URLs, visuals, and other materials will be provided during class orposted on Blackboard.

· Principle of geotechnical Engineering by Braja M. Das, 7th

Edition, Cengage Learning(2010).

· Engineering Properties of Soils and Their Measurements by Joseph E. Bowles, 4th

Edition, McGraw-Hill (1992).

· Soil Mechanics Lab Manual by Michael Kalinski, John Wiley (2006)

· Annual Book of American Society for Testing and Materials (ASTM) Standards.

Office HoursTuesday 10:00 – 11:00

Course DescriptionBehavior and properties of soils, Application to foundation and slope design, liquefaction, andseepage.

Course Learning ObjectivesThis course will provide the students with sufficient guidance and resources to learn theproperties and behavior of soils in accordance with the principle of soil mechanics, theexperimental method of testing as well as data interpretation and presentation, and theapplication of soil test data for the design of engineering structures. Upon completion of thiscourse the students will be able to:

Ø Acquire basic knowledge about the properties and behavior of soils in accordance withthe principles of soil mechanics and foundation engineering.

Ø Use experimental methods and testing equipments related to earth, earth supported, andearth retaining structures and foundations.

Ø Utilize test data to determine engineering properties of soils to solve basic engineeringdesign problems in geotechnical field.

Ø Prepare reports based on test results following evaluations.



Topics CoveredParticle Size AnalysisSpecific GravityPlasticity LimitsSoil Classification for Engineering PurposesPermeabilitySeepage AnalysisSoil CompactionConsolidationDirect Shear TestUnconfined Compression TestTriaxial Shear TestSlope Stability Analysis and Design

Program Educational Objectives

The educational objectives of the program are as follows:

· Technical Growth: Graduates will be successful in modern engineering practice, integrate

into the local and global workforce, and contribute to the economy of California and the

nation.

Assessment of Student’s LearningThe effect of this course on student’s learning ability will be assessed according to the followingcriteria:

Ø An ability to apply knowledge of mathematics, science, and engineering.Ø An ability to design and conduct experiments as well as to analyze and interpret data.Ø An ability to communicate effectively.Ø An ability to use the techniques, skills, and modern engineering tools necessary for

engineering practice.

Laboratory Reports and Other Assignments

· This course is incorporated in one of the upper-division writing courses requirements. Gradeof ‘C’ or above is required to satisfy the upper-division writing requirement.

· Students are required to submit a report of the lab works conducted in each week. Report isdue at the beginning of the class in the following week. There will be no credit for the latesubmission, unless accompanied with a university approved excuse. Lab reports should beprepared according to the report format and guideline provided by the instructor. Quality ofpresentation, technical writing quality, summary and conclusion, and technical informationpresented in the report are the major factors for the evaluation of the report. Writing andsketches should be neat. Students are required to make a PowerPoint presentation of one ofthe assigned projects in a group. Members of a group will be assigned in the beginning of thelab works.

· It is clear that employers look for persons who have excellent oral and written communicationskills. Therefore, all parts of the reports should be written in complete sentences using goodtechnical English. Substandard writing may reduce the score for the reports by up to 50%.

Please remember to use a dictionary (or the spell-checker in the word processor), proofreadthe report, and revise it if necessary. Please strive to achieve a professional quality in thesebrief reports. Sloppiness, lack of organization, scribbled notes, etc. will result in lower grades.

Scheduled ExamsThere will only be the final exam for this course. The final exam will be comprehensive and willcover the contents covered in the entire class.



Grading PolicyThe final letter grade will be computed using the following criteria:

· Lab Reports/Projects/Laboratory Neatness/Participation 40%

· Mid-Term I Exam (October 1) 20%

· Mid-Term II Exam (November 12) 20%

· Project Report and Presentation

(Final Exam) (December 17) 20%

Letter Grades

· A+

(> 97%) A (93 – 96.9%) A-(90 – 92.9 %)

· B+

(87 – 89.9%) B (83 – 86.9%) B-(80 – 82.9 %)

· C+

(77 – 79.9%) C (73 – 76.9%) C-(70 – 72.9 %)

· D+

(67 – 69.9%) D (63 – 66.9%) D-(60 – 62.9%)

· F (< 60%)

Honor Code

· “California State University, Fullerton's Honor Code” explained in UPS 300.021 applies to allworks performed in this class including homework, quizzes, and examinations. Students should

strictly follow those codes.· This is a professional course. A learning environment will be created in each class for motivated

students; therefore professional conduct is expected of all participants. Professional conductextends to use of cell phones, personal computers, iPods and PDAs during lecture. Studentsviolating such professional conducts are subject to expulsion from the class.

· Students should strictly follow the safety regulations mentioned by the instructor. Studentsviolating the safety regulation will not be allowed to conduct the lab on that particular day and willbe counted as absent.

Drop PolicyThe Fall 2013 Schedule contains the University Regulations and Deadlines for dropping thiscourse. Students should note that the department stamp and/or department chair’s signature isalso required in addition to instructor’s signature to drop the course.

Students with Special NeedsStudents who need adaptations or accommodations because of a disability (e.g. learning,attention deficit disorder, psychological, physical, etc.), or have emergency medical information toshare with the instructor, or need special arrangements in case the building must be evacuated,are requested to make an appointment to discuss their needs with the instructor during the firstweek of classes.



Detailed Class Schedule

Week Day Topic/s Section in Textbook Report Due

1 August 27Course Introduction andGuidance on Report Writing

Handout & 1

2 September 3Sieve and Hydrometer

Analysis, Specific GravityTest

3, 4, & 5

3 10Liquid Limit, and PlasticLimit Tests

6 & 7

5 17 Soil Classification 9

6 24Standard/ModifiedCompaction Tests

12 & 13Report 1:

Classification of Soil

9 October 1 Mid – Term Exam I Report 2:

Compaction

7 8Constant and Falling HeadPermeability Tests

10 & 11

8 15 Direct Shear Test 15 Report 3:Permeability

9 29 Stage Consolidation Test 17Report 4:

Direct Shear

10 November 5 Stage Consolidation Test 17

11 12 Mid – Term Exam II Report 5:

Consolidation

12 19Unconfined CompressionTest

16

13 November 25-29 Fall Recess No Class

14 December 3 UU Triaxial Test 18Report 6:UC Test

15 10 Slope Stability Analysis &Design

Handout Report 7:UU test

16 17 FINAL EXAM (GroupPresentation)

Group Report



Emergency Procedures Notice to Students

The safety of all students attending California State University Fullerton is of paramountimportance. During an emergency it is necessary for students to have a basicunderstanding of their personnel responsibilities and the University’s emergency responseprocedures. In the event of an emergency please adhere to the following guidelines

Before an emergency occurs-

1. Know the safe evacuation routes for your specific building and floor.2. Know the evacuation assembly areas for your building.

When an emergency occurs-

1. Keep calm and do not run or panic. Your best chance of emerging from anemergency is with a clear head.

2. Evacuation is not always the safest course of action. If directed to evacuate, take allof your belongings and proceed safely to the nearest evacuation route.

3. Do not leave the area, remember that faculty and other staff members need to beable to account for your whereabouts.

4. Do not re-enter building until informed it is safe by a building marshal or othercampus authority.

5. If directed to evacuate the campus please follow the evacuation routes establishedby either parking or police officers.

After an emergency occurs-

1. If an emergency disrupts normal campus operations or causes the University to closefor a prolonged period of time (more than three days), students are expected tocomplete the course assignments listed on the syllabus as soon as it is reasonably

possible to do so.2. Students can determine the University's operational status by checking the

University's web site at http://www.fullerton.edu, calling the University's hotline

number at 657-278-0911, or tuning into area radio and television stations. Studentsshould assume that classes will be held unless they hear or read an official closureannouncement.

EMERGENCY CALLS

DIAL 9-1-1

All campus phones and cell phones on campus reach theUniversity Police Department

Non-emergency line: (657) 278-251524-hour recorded emergency information line: (657) 278-0911

(657) 278-4444



CALIFORNIA STATE UNIVERSITY, FULLERTONCollege of Engineering and Computer Science

CIVIL AND ENVIRONMENTAL ENGINEERING DEPARTMENT

EGCE 324L Soil Mechanics Laboratory(Fall 2013)

LABORATORY SAFETY GUIDELINES

Introduction

Laboratory safety awareness is an important mindset that protects people, expensive equipment,

and the university resources while conducting laboratory experiments. Individuals working in the

Soil Mechanics Laboratory (EGCE 324L) facilities are always required to exhibit maturity and follow

proper operation procedures while operating equipment and conducting laboratory tests. This

responsibility implies upon entering the laboratory. The guidelines given herein are intended to

minimize personal accidents and equipment damage. Please be sure to follow the following four

mandatory rules while conducting the laboratory works.

v If you are not sure about what and why you are doing any task, please ask your

instructor.

v While conducting a lab experiment, safety of yourself and that of those around you are

paramount – make sure that everyone around you is aware of what is going on.

v Please do not leave any equipment unattended. Pack each equipment properly after

washing it and return to its original position.

v Please do not touch anything in the laboratory that is not a part of the experiment/s you

are conducting.

Laboratory Dress

While attending a laboratory task for this course, you must be appropriately attired for the

particular work related to the lab work. Some of the simple guidelines include:

v Wear sensible closed-toed shoes or boots; open-toed shoes, sandals, or bare feet are not

acceptable laboratory attire.

v Wear long pants; shorts and skirts are not acceptable laboratory attire.

v Refrain from wearing clothing accessories that may become caught in laboratory equipment.

v Put long hair in a ponytail or contain properly.

v Wear eyeglasses or contacts, if needed.

v Use safety glasses and ear plugs, when necessary.

v Wear gloves, face masks, protective shoes or boots, as appropriate, depending upon the

nature of the lab work.

Laboratory Procedures

A wide variety of equipment and testing apparatus reside in the laboratory. The complexity of

many of these devices necessitates specific care and consideration while operating them. If there

is any doubt or any question on operating any piece of equipment while performing laboratory work,

consult with the instructor or the lab technician.



Guidelines for laboratory safety are necessary to minimize accidents and to ensure that expensive

equipment is not damaged by carelessness or negligence. The following are some of the basic rules

pertinent to lab safety:

v Turn on the lights upon entering the laboratory. Turn off the lights if you are last to leave

the laboratory.

vDo not handle any materials or operate any equipment unrelated to the EGCE 324Llaboratory experiment to be performed on that particular day.

v Never operate any unfamiliar equipment without a specific approval of the instructor or the

lab technician.

v Be sure to clean and dry out the equipment after you are done with the experiments.

v When operating very important equipment, be sure that at least two persons are always

present.

v Be careful while using and storing sharp edge equipment like knives.

v No food or beverages are allowed in the laboratory.

v No smoking is permitted in the laboratory.

v Be aware of your surroundings. Keep fingers away from large machinery.

vWear appropriate clothing and shoes.

v Place all laboratory equipment in their proper storage area after use.

v Always follow a professional manner.

Accidents

v In case of any type of accident and/or if someone is hurt, seek help immediately. Behave as

a responsible citizen in case of serious accidents and report to the concerned authorities.

If such thing happens, call the instructor immediately (301-310-4628). If the instructor is

not available, call lab technician (657-278-3134) or Civil Engineering Office (657-278-

3012).

v If equipment is damaged, please report the situation to the instructor promptly. This will

assure a proper and quick repair or replacement.v In the event of major fire, please evacuate the building immediately and seek professional

help (university police: 657-278-2515). In the event of a minor fire, use the nearest fire

extinguisher to extinguish the flame and/or seek the assistance of the instructor (301-310-

4628) and/or lab technician (657-278-3134).

Security

Proper security of the laboratory facilities also ensures a safe working environment. The following

are some of the guidelines:

v If you are the last to leave the laboratory room, please lock and close the doors and

windows prior to your departure.

v After you have finished using any equipment, please return it to its proper storage area andcabinet.

v Report any suspicious individuals or unwanted visitors not related to the laboratory to the

lab technician (657-278-3134) or university police (657-278-2515).



ACKNOWLEDGEMENT OF RECEIPT FORM

EGCE 324L Soil Mechanics Laboratory(Fall 2013)

LABORATORY SAFETY GUIDELINES

Acknowledgement of Receipt

I hereby acknowledge that I have read the entire guidelines mentioned above regardingthe proper procedures and conduct to be followed in the laboratory experiments for SoilMechanics Laboratory (EGCE 324L). As a student at California State University,Fullerton, I understand these guidelines and procedures and agree to abide by them.

Course Title: Soil Mechanics Laboratory (EGCE 324L)

Term/Year: Fall 2013

Name:

Signature:

Date:

Please submit this form, completed and signed, to your instructor by the end of the first

laboratory period. Failure to do so will result in an incomplete grade for the term.



GRAIN SIZE DISTRIBUTION ANALYSISSIEVE ANALYSIS

Application

Grain size distribution analysis is used to classify soils for engineering purposes, andother geotechnical applications, such as, filter design and other applications

mentioned at the bottom of the manual. ASTM D422 explains about the procedure

of grain size distribution analysis. Grain size distribution is done with sieve analysis

and/or hydrometer analysis. This chapter deals with the sieve analysis only.

EquipmentSieves (US sieve No. 4, 10, 20, 50, 100, 200)

A bottom pan and cover

Scale capable of measuring to the nearest of 0.01g

Mechanical sieve shaker

Stop watchEmpty bowl

Brush

Procedurei. Measure weight of an empty bowl.

ii. Collect approximately 500 g of a representative oven dry soil specimen, finer

than 4.75 mm.

iii. Break the soil samples into individual particles by hand or any other tool such as

mortar and pestle.

iv. Pour the soil into the bowl and weigh the mass of soil and bowl.

v. Prepare a stack of sieves, largest size sieve at the top and smallest sieve size

at the bottom. US No. 4 sieve should be at the top and US No. 200 sieve should

be at the bottom. Set the pan below the No. 200 sieve.

vi. Pour the soil into the top sieve, and cover it.

vii. Put the assembly into a mechanical shaker, tighten all the screws, and turn the

shaker on.

viii. Shake the assembly for about 5 minutes.

ix. Wait for about 3 minutes, and remove stacks of sieve.

x. Weigh the soil mass that is retained on each sieve and the bottom pan. For this,

empty the bowl and measure its weight. Fill the bowl with the soil retained in

each sieve. Then measure the weight of the bowl and soil. Populate the table 1.

xi. Sum up the quantity of soil retained on each sieve and the pan. If the total

weight is less than the initial weight by more than 1%, repeat the procedure.



Calculations1. Calculate the % of soil retained on the ith sieve

Ri = 100,

,Re

W MassTotal

W tained Mass i

2. Calculate the cumulative % of soil retained on the ith sieve

i R

ii

i

i R1

3. Calculate the % of soil passing through the ith sieve

% finer =

ii

i

i R1

100

4. Populate the attached table completely using the above equation.

5. Make a graph of particle size in mm (log scale) in X-axis and % finer (in

arithmetic scale) in Y-axis using the graph paper shown in figure 1. You can use

your own “excel spread sheet” or other computer programs to make this graph.

6. Determine D10, D30, and D60 from the graph, which correspond to the particle

size for 10% finer, 30% finer, and 60% finer. Determine the D50, D15, D85, and

D90 also.

7. Calculate uniformity coefficient (Cu) and coefficient of gradation (Cc) using the

following equations.

10

60

D

DC u

1060

2

30

D D

DC c

Note:

D10 is also called effective size and is used to estimate coefficient of permeability.

Cu shows whether the soil is well graded or poorly graded.

Cc complements Cu to evaluate whether the soil is well graded or poorly graded, or

gap graded. They are used for Unified Soil Classification System (USCS).

D90, D15 and D85 are used to design filters. D50 is used in liquefaction analysis.



Particle Size Analysis Procedure

Tested by: Tested Date:

Lab Partners/Organizations: Group:

Client: CSUF CEED Project: EGCE 324 L

Boring No.: N/A Recovery Date: N/A

Soil description:

Sieve shaking method/duration:

Total sample mass before sieving (Wtotal):

Total sample mass after sieving (Wtotal’):

% soil loss during sieving:

Table 1 Lab measurement data for particles size analysis

Sieve

No.

Sieve

Opening(mm)

Mass of Soil Retained

on Each Sieve, Wi (g)

% of Mass Retained on

Each SieveRi

Cumulative %Retained,

i R

% Finer

100- i R

4

10

20

40/ 50

100

200

Pan

% Loss during sieving = 100

'

total

total total

W W W



Figure 1 Gradation sheet to plot the grain size distribution curve



HYDROMETER ANALYSIS (ASTM D 422)

ApplicationHydrometer analysis is done to measure the proportion of particles smaller than

0.075 mm.

EquipmentASTM 152H Hydrometer

Mixer cup

Two 1000 cc graduated cylinder

Thermometer

Constant Temperature Bath

Sodium hexametaphosphate

Spatula

Beaker

BalanceSqueeze bottle

Rubber Stopper

Procedurei. Combine 50g (Md) of the soil passed through #10 sieve with 125 ml of sodium

hexametaphosphate solution (4%) in a 250 ml glass beaker. Allow the mixture to

soak for 16 hours (for demonstration today, 30 minutes will be enough ).

ii. Transfer all of the mixtures to an ASTM D422-specified dispersion cup. Wash

all the soil solids from inside of the beaker into the dispersion cup. Fill the cup

with water (half of the cup).

iii. Stir the mixture with a mechanical stirrer at the rate of 10,000 rpm for oneminute.

iv. Pour the slurry into a 1000 ml etched cylinder and fill with distilled water to

just below the etch mark. Wash all the slurry from cup into the cylinder using

squeeze bottle.

v. Using a rubber stopper, mix the soil water mixture by turning it upside down and

back at a rate of 1 turn per second for 1 minute.

vi. Set the cylinder on a water bath (or table) and start the timer immediately.

Wash the remaining soil off the stopper and lip of the cylinder with the squeeze

bottle and fill the cylinder to the etch mark with distilled water.

vii. Insert the hydrometer slowly and take the first hydrometer reading at 2 min,

with subsequent readings at 5, 15, 30, 60, 240, and 1440 minutes. Thehydrometer reading is taken at top of the meniscus.

viii. Remove the hydrometer after each reading, and place it in a 1000 ml cylinder

filled with distilled water between readings. Spin the hydrometer in the water-

cylinder to take off the adhered soil particles.

ix. Record the temperature of the mixture.



Calculations1. Calculate diameter of particle at time t.

t

Lk D

K can be calculated for given Gs and temperature using Table 1.

L (in cm) = 16.3 – 0.163 R

2. Percentage passing for the specific diameter is calculated as,

%100)(

'

d M

ab R P

Values of a and b can be calculated using Table 2.

3. Calculate overall % passing as,

40#' P P P

Table 1 Value of K for different Gs and Temperature

Table 2 Values of Correction Factors a with Gs

Gs a

2.5 1.03

2.55 1.02

2.6 1.01

2.65 1.00



2.7 0.99

2.75 0.98

2.8 0.97

2.85 0.96

Table 3 Values of Correction Factors b with temperature

Temperature

(oC)

b

17 5.9

18 5.6

19 5.3

20 5.0

21 4.7

22 4.4

23 4.1

24 3.8



GRAIN SIZE ANALYSIS – HYDROMETER MEASUREMENT (ASTM D422)

LABORATORY DATA SHEET

I. GENERAL INFORMATION

Tested by: Date tested:

Lab partners/organization: Group

Client: CSUF CEED Project: EGCE 324L

Boring no.: N/A Recovery depth: N/A

Recovery date: N/A Recovery method: N/A

Soil description:

II. TEST DETAILS

Hydrometer manufacturer/serial no.:

Mixer manufacturer/serial no.:

Scale type/serial no./precision:

Duration of initial soaking period:

Concentration of sodium hexametaphosphate solution: 4%

Dry mass of soil used ( M d ):

Specific gravity of soil solids: Temperature:

K: a: b:

Notes, observations, and deviations from ASTM D422 test standard:

II I. MEASUREMENTS AND CALCULATIONS

Clock Time

(hh:mm:ss)

t

(min)

R L

(cm)

D

(mm)

P’

(%)

P

(%)

IV. EQUATION AND CALCULATION SPACE

L = 16.3 – 0.163 R t / L K D

100% x M

a )b R( ' P

d

P = P’(P -#40 )



SPECIFIC GRAVITY TEST (ASTM D 854)Application

Specific gravity of soil is important in hydrometer analysis, weight volume related

calculations, etc.

Equipment500 ml etched flask

Squeeze bottle

Scale capable of measuring to the nearest of 0.01g

Thermometer (minimum 0.50C capacity)

Funnel

Vacuum supply stopper

Vacuum supply

Procedure

i.

Take approximately 60 g of dry soil and take exact weight measurement (M o).ii. Fill the flask up to the etch line with distilled water and measure weight (M a).

iii. Pour half of the water out of the flask and place the soil in the flask with a

funnel.

iv. Wash the soil down the inside neck of the flask.

v. Connect the flask to the vacuum source with the hose and stopper and apply

vacuum for 30 minutes, occasionally agitating the mixture.

vi. Fill the flask to the etch line with distilled water and weigh it (Mb).

vii. Record the water temperature in the flask.

Calculations

1. Calculate specific gravity (Gs) using the following equation.

)(0

0

ba

s M M M

M G

2. Apply the following temperature correction factor and calculate the Gs value for

200C.

K GG s s .20

Table 1 Temperature Correction Factor (K)

Temperature (0C) Correction Factor (K)

17 1.0006

18 1.000419 1.0002

20 1.0000

21 0.9998

22 0.9996

23 0.9993

24 0.9991



SPECIFIC GRAVITY OF SOIL SOLIDS (ASTM D854)




Lab partners/organization: GroupClient: CSUF CEED Project: EGCE 324L



Soil description:

II. TEST DETAILS

Vacuum level: Duration vacuum applied:

Flask volume:

Scale type/precision/serial no.:Notes, observations, and deviations from ASTM D854 test standard:

III. MEASUREMENTS AND CALCULATIONS

Test ID

Mass of flask filled with water (M a )

Mass of flask filled with soil and water (M b )

Mass of dry soil (M o )

Specific gravity of soil solids (G s )

Water temperature

Correction factor (K )

Specific gravity of soil solids at 20oC (G s20 )

IV. EQUATION AND CALCULATION SPACE

) M M ( M

M G

bao

o s

G s20 = G s K



LIQUID LIMIT

ApplicationLiquid limits are used to classify soil, correlate various soil properties with strength,

estimate swelling potential of soil, and hundreds of similar uses in geotechnical

engineering.

EquipmentCasagrande Liquid Limit Device

Grooving tool

Moisture cans

US No. 40 sieve

Distilled water

Plastic squeeze bottle

Scale

Ceramic soil mixing bowlOven

Frosting knife/spatula

Procedure3. Determine mass of the moisture can (W1).

4. Put about 300 g of air dry soil, passed through No. 40 sieve into a ceramic bowl and

add distilled water from plastic squeeze bottle. Mix the soil for some time to form a

uniform paste. (It is worthy to soak the sample with water for 48 hours before the

test, but we don’t have enough time in our lab to do so).

5. Place a portion of the paste in the brass cup of the liquid limit device. Smooth the

surface of the soil in the cup with spatula (keep maximum depth of soil in the cup toabout 8 mm).

6. Cut a groove along the center line of the soil pat in the cup.

7. Turn the crank of the liquid limit device at the rate of about 2 revolutions per

second. Drop height should be exactly 1.0 cm – check it. Closely observe the groove.

8. Count the number of blows (N) to close the grove over a length of 0.5 inches.

9. If N is more than 35, add some water into the soil, mix it and repeat the procedure.

If N is between 25 and 35, note the value of N and transfer a portion of the paste

to a moisture can and weigh (W2).

10. Clear the soil from the cup, wipe out the cup, and mix the soil with water. Repeat

the procedure until the grove is closed at 20-25 blows/cranks. Transfer the soil to

the moisture can and weigh. Repeat the procedure again to get the grove closed at15-20 blows. Although 3 tests are enough to get the desired value, it is advisable to

conduct 5 different tests to give N ranging from 12-35.

11. Put all moisture cans into the oven and dry them to a constant mass. Weigh the mass

of dry soil plus the can (W3) after 24 hours.



Calculations

12. Calculate the moisture content of the soil.

Moisture content (w%) = 10013

32

W W

W W

13. Plot a graph for moisture content at Y-axis and Number of blows (in log scale ) at X-axis. The points will end up with a straight line with negative slope. This line is called

a flow line. Calculate the magnitude of the slope of the flow line. This slope is called

flow index.

14. Using the equation of flow index, calculate the moisture content for 25 blows.

15. Liquid limit is the value of w% at 25 blows.

Note:

The slope of the flow line will give Log (N), and we need to convert it to N while

calculating the values. Or you can use ‘excel spreadsheet’ to plot the result and

derive the value of N.



Liquid Limit Test Results


Lab Partners/Organizations:

Client: CSUF CEED Project: EGCE 324L


Soil description:

Oven temperature: Drying time:

Precision of scale: Note:

Table 1 Measurement data for the water content of the particular test and corresponding N

Test No. 1 2 3 4 5

Can No.

Mass of can, W1 (g)

Mass of can + moist soil, W2 (g)

Mass of can + dry soil, W3 (g)

Moisture content, w%

Number of blows, N

Flow Index:

Liquid Limit:



50

40

30

20

10

0

M o i s t u r e C o n t e n t , w ( % )

3 4 5 6 7 8 9

102 3 4 5

Number of Cranks

Figure 1 Graph to plot number of blows and corresponding moisture content.



PLASTIC LIMIT

ApplicationPlastic limits are used to classify soil, correlate various soil properties with strength,

estimate swelling potential of soil, and hundreds of similar uses in geotechnical

engineering.

EquipmentSpatula/Frosting knife

Moisture cans

US No. 40 sieve

Distilled water

Plastic squeeze bottle

Scale

Ceramic soil mixing bowl

OvenFrosted glass plate

Procedure16. Determine mass of the moisture can (W1).

17. Put about 100 g of dry sample passed through US No. 40 sieve, into a ceramic soil

mixing bowl.

18. Add distilled water and mix it thoroughly to make a number of sticky mud-balls.

19. Take a ball of size slightly bigger than a pea-size, and roll it on the frosted glass

plate using the palm of your hand to form a thread of 3.18 mm diameter,

approximately (the exact size rod is provided to you). Then break the soil to several

pieces and repeat the procedure to make the thread.20. If the thread crumbles exactly at the diameter of 3.18 mm, transfer the thread

into the can and weigh (W2).

21. Put the can into the oven, weigh it after 24 hours when it is dry (W3).

22. Populate table 1.

23. Repeat the above mentioned procedure for at least 5 times, although 3 samples are

enough to get the plastic limit.

Calculations24. Calculation of the moisture content of the soil.

Moisture content (w%) = 10013

32

W W

W W

25. This moisture content is the plastic limit. Average value of three or more acceptable

tests is considered as the plastic limit of the soil.



Plastic Limit Test Result


Lab Partners/Organizations:

Client: CSUF CEED Project: EGCE 324 L


Soil description:

Oven temperature: Drying time:

Precision of scale: Note:

Table 1 Measurement of moisture content for different soil specimens.

Test No. 1 2 3 4 5

Can No.

Mass of can, W1 (g)

Mass of can + moist soil, W2 (g)

Mass of can + dry soil, W3 (g)

Moisture content, w%

Average Plastic Limit, %

Plasticity Index*:

*Plasticity Index (PI) = LL - PL



SOIL CLASSIFICATIONApplication

A classification scheme provides a method of identifying soils in a particular group

that would likely exhibit similar characteristics. Soil classification is used to specifya certain soil type that is best suitable for a given application. There are several

classification schemes available. Each was devised for a specific use. For example

American Association of State Highway and Transportation Officials (AASHTO)

developed one scheme that classifies the soil according to their usefulness in roads

and highways. However, Unified Soil Classification System (USCS) was originally

developed for use in airfield construction, but was later modified for general

purpose. AASHTO and USCS are two major classification systems in use.

Information needed

Grain size distribution curve

Plasticity information of the soil – LL, PL, and PIASTM D 2487

AASHTO M 145

Procedure

USCS Classification

26. Determine the % of soil retained on #200 sieve (R200).

27. If R200 is greater than 50%, it is a coarse grained soil otherwise it is a fine grained

soil.

28. For fine grained soil:

a. Find whether the soil is organic, by comparing the liquid limit of oven driedspecimen with that of the original specimen. If the LL of oven dried

specimen is less than 75% of that of the non oven dried specimen, the soil is

organic. Otherwise, the soil is inorganic.

b. Plot the LL and PI values on the plasticity chart, and find the group symbol

for the soil.

c. Determine % of soil retained on the US #4 sieve (R4). This is the % of

gravel fraction (GF) in the soil.

d. Determine the % of sand fraction (SF) in the soil by, SF = R200 – GF.

e. Use the ASTM table to classify the fine grained soil.

29. For coarse grained soil,

a. If % of gravel is more than % of sand, it is gravelly soil otherwise sandy.b. Using the grain size distribution curve, calculate Cc, and Cu.

c. Using the ASTM chart for the coarse grained soil, classify the soil. Be

careful to check whether they fall under dual classification or not.

AASHTO Classification

1. Determine the % of soil passing through #200 sieve (F200). If F200 is more than

35% soil is fine grained otherwise coarse grained.



2. For coarse grained soil:

a. Determine F10, F40, F200, LL, and PI.

b. Match the soil group based on the AASHTO Classification.

3. For fine grained soil:

a. Determine LL, and PI.

b. Group soil according to the AASHTO classification.4. Determine Group Index (GI) of the soil as:

Group Index : GI = (F-35)(0.2+0.005(LL-40)) + 0.01(F-15)(PI-10)

5. Express GI in whole number.

6. Express the classification first by soil classification and then GI in parenthesis.

Calculations

30. Calculate the % of soil retained on the #200 sieve

R200 = (100 – F200)

31. Calculate the % of soil retained on the #4 sieve

R4 = (100 – F4)

32. Calculate uniformity coefficient (Cu) and coefficient of gradation (Cc) using the

following equations.

10

60

D

DC u

1060

2

30

D D

DC c

33. Calculate Group Index (GI)

GI = (F-35) (0.2+0.005 ( LL-40 ) ) + 0.01 (F-15) (PI-10)



Classification of Soil

A classification scheme provides a method of identifying soils in a particular group that

would likely exhibit similar characteristics. Soil classification is used to specify a certain

soil type that is best suitable for a given application. There are several classification

schemes available. Each was devised for a specific use. For example American Association of

State Highway and Transportation Officials (AASHTO) developed one scheme that

classifies the soil according to their usefulness in roads and highways. However, Unified Soil

Classification System (USCS) was originally developed for use in airfield construction, but

was later modified for general purpose.

USCS

The USCS uses symbols for the particular size group:

G – Gravel particles retained on #4 sieve (4.75 mm)

S- Sand particles passing #4 sieve, but retained on # 200 sieve (0.075 mm)M- Silt particles passing # 200 sieve

C- Clay particles passing # 200 sieve

These are combined with other symbols with expressing gradation characteristics

W- Well graded

P- Poorly graded

And, plasticity characteristics (figure 1)

H – High plasticity L- Low plasticity O- Organic matter

Figure 1 Plasticity chart for the USCS classification of fines



Figure 2 USCS Classification Chart

AASHTO Soil Classification System

The AASHTO soil classification is used to determine the suitability of soils for earthworks,

embankments, and road bed materials (sub base and sub grade). According to AASHTO

classification,

Gravel 75 mm – 2 mm (#10 sieve)

Sand 2 mm – 0.075 mm (#200 sieve)

Silt and Clay <0.075 mmSilty: PI <10%

Clayey: PI >11

AASHTO classification classifies soil into 7 major groups: A-1 through A-7.

A-1 – A-3 : Granular or coarse grained soil

A-4 – A-7 : Silty clay or fine grained soil



Figure 3 AASHTO soil classification chart

Silty and clayey soils can be located in a plasticity chart as shown in the figure below.

Figure 4 Plasticity chart for the AASHTO classification system



A group index value (GI) is appended in parentheses to the main group to provide a measure

of quality of a soil as highway sub grade material. The group index is given as:

Group Index : GI = (F-35) (0.2+0.005 ( LL-40 ) ) + 0.01 (F-15) (PI-10)

Where,F = % finer than #200 sieve size.

GI is expressed in a nearest whole number. If GI is less than 0, set it to 0. If any terms in

the above equation are less than 0, set them to 0. For them partial group index is used. The

higher the group index, the lower the quality of soil as sub grade material. GI should not

exceed 20 for any of group A-4 through A-7.



LABORATORY COMPACTION TEST

Application

Compaction of soil is probably one of the largest contributors to the site work economy; inother words-it is important. Large sums of money are spent on it every day. Soil is a very

flexible and inexpensive construction material. It can be manipulated to produce a material

with a wide range of properties. Control of compaction in the field permits civil engineers

to engineer a soil to produce a material with properties that are optimized for a project.

Compaction is defined as the reduction in soil void ratio by expulsion of air from the voids.

In contrast, the consolidation process is the reduction of void ratio by expulsion of water

from the voids. These two processes are similar in that they result in a decrease in void

ratio. Compaction occurs instantly with application of a force. Consolidation is a time-

dependent process that can take many years to complete after a load is applied to soil.

Because compaction involves reducing the void ratio without changing the moisture content,the degree of saturation will increase.

Soil is compacted to improve the following soil properties and aspects of strength-

deformation behaviors:

Improve shear strength

Reduce compressibility

Decrease permeability

Reduce shrink/swell potential

Reduce liquefaction potential

Reduce compression due to wetting

The behavior of a soil during compaction and after compaction depends on:

soil type (fine vs. coarse grained)

compaction moisture condition

method of compaction

A variety of methods and machinery are used to compact soil.

Compaction of Fine-Grained Soils

When fine-grained soils are compacted they display a strong dependency on compaction

moisture content. Proctor (1933) described this behavior through the concept of the

"moisture – unit weight relationship ". This is also loosely (and unfortunately all too



commonly) referred to as the moisture-density relationship even though the "density" is

actually unit weight.

It was found that, for any given amount of energy expended in compacting the soil, there

existed an optimum moisture where the dry density was greatest. This relationship is

shown in Figure 1 (from Hilf, Chapter 8. “Compacted Fill”, Foundation Engineering Handbook,

Fang, Editor, 1991).

The tests shown on Figure 1 are the result of two “Proctor compaction tests” on one soil. In

these tests, soil is compacted by a series of blows of a standard hammer in cylindrical molds

that have a known standard volume. The hammers are designed to provide a known,

repeatable input energy. Table 1 provides the details of each test. The complete moisture

– unit weight relationship is obtained by compacting soil at a series of different moisturecontents (but using the same effort each time). A smooth curve between the points is

drawn and the maximum dry unit weight and optimum water content are determined for a

soil at that compaction effort. The maximum dry unit weight is the peak point on the curve

and the optimum moisture content is the water content corresponding to that peak dry unit

weight.

Table 1. Details of Standard and Modified Proctor Tests.

Test Mold*

Volume

No. of

Layers

Blows/

layer

Hammer

Weight

Drop

Height

Energy

Input

Standard Proctor

(ASTM D 698)

1/30 ft3 3 25 5.5 lb 12 in 12,400

ft lb/ft3

Modified Proctor

(ASTM D 1557)

1/30 ft3 5 25 10 lb 18 in 56,000

ft lb/ft3

*4.0” diameter x 4.6” tall mold

The influence of standard effort vs. modified effort on the moisture-density relationship is

shown in Figure 1. Note as the compaction effort is increased, the maximum density

Figure 1 Moisture – unit weight relationships for a soil using two compaction efforts.



G sw e

increases and the optimum moisture content decreases. The differences in the tests are in

the amount of energy transmitted to the soil with each hammer blow and are shown below.

To the left of optimum moisture the soil is referred to as “on the dry side”. Similarly,

points to the right of optimum (higher moisture contents) are referred to as “on the wet

side”.

Relative compaction is typically used as an index to compare the field density with the

laboratory density. Relative compaction is defined as:

Relative Compaction: %100max,

d

d RC

(1)

Where,

d = field density measured in the field

d, max = Proctor maximum dry density obtained from a Proctor Test.

This is expressed as a percentage.Note:

Relative compaction is based on dry unit weights . RC greater than 100% is possible.

The Zero Air Voids Line

The zero air voids (ZAV) line is the combination of moisture and density that produce

complete saturation of the soil or the d obtained when there is no air in the void spaces.

The compaction curve theoretically does not cross this line but becomes parallel to it.

Remember that the values of water content, wet unit weight, and specific gravity are not

constant throughout the soil. There could also be variability in the test results. Variability

can result in points on the compaction curve above the ZAV line (S>100%). These datapoints should not be thrown out.

Basic weight volume relationships are used to develop and equation for the ZAV line. Recall

that:

e

G

eV V

V G

V V

W

V

W w s

s s

sw s

v s

sd

1

Since S = 1 if the saturation is equal to 100 percent, the relationship:

can be substituted into the above equation to yield the final equation for the ZAV line:

w+ G

G

S

wS d

1

(2)

Note that G s and w are constants for a given soil. Therefore the ZAV line is a linear

function of water content. To draw the ZAV line, simply enter values of w and compute the

corresponding value of d .



LABORATORY PROCEDURE (Modified Proctor)

Equipment

Compaction moldUS Sieve # 4

Modified Proctor Hammer

Balances sensitive to 0.01 lb, 0.1 g

Large flat pan

Jack

Steel straight edge

Moisture bowls

Drying oven

Plastic squeeze bottle with water

Procedure

1. Obtain approximately 5 lbs. of undried soil passing the No. 4 sieve for each test

being performed. A minimum of 5 tests is required, 6 is preferred.

2. Add enough water to each test sample to bring the water content within range

of optimum. Test samples should be prepared in approximately 2% increments.

First trial water content might be 4% (recommendation – 4%, 6%, 8%, 10% …).

3. Determine the weight (W1) and volume (V) of the Proctor compaction mold with

base plate (do not measure the extension). Use the scale sensitive to 0.1 lb to

determine the weight of the mold.

4. Determine the weight (Wtin) of the moisture bowls. Use the scale sensitive to.01 g to determine these weights.

5. Assemble and secure the mold and extension to the base plate. Spray lubricant

in it, which will help sample extrusion afterwards. Make sure that the apparatus

is placed on a rigid foundation (i.e., concrete slab). This is important not only for

safety reasons, but to ensure that the compaction effort is applied to the soil

and not the foundation.

6. Compact the first test specimen in the mold in five equal layers.

a. For the first layer, fill the mold about one third with loose soil.

b. Compact the lift with 25 blows of the compaction hammer. Make sure

that the hammer is kept vertical and the guide sleeve is not lifted. Also,

take care to evenly distribute the blows over the entire mold.

c. Score the top of the layer with a metal spatula.

d. For the second layer, fill up to two third level of the mold.

e. Repeat steps b and c.




EGCE 324L (Soil Mechanics Laboratory)

f. For the final layer, fill to about the midpoint or higher of the extension.

This layer is important because after compaction, the top of the layer

must be equal to or above the top of the mold. If it is not the test must

be done over.

g. Repeat step b.

7. Remove the extension.

8. With the steel straight edge level off the sample so it is even with the top and

bottom of the mold. Take care not to create divots in the sample during this

process.

9. Determine the weight (W2) of the soil and mold plus base plate (not the

extension). Use scale sensitive to 0.1 lb. to determine this weight.

10. Take off the base plate and with the aid of the extruder, remove the sample

from the mold.

11. Collect a sample of soil from the center of the compacted soil and place it in themoisture tin.

12. Determine the weight (Wtin+soil) of the moisture bowl and soil.

13. Place the moisture bowl and soil in the oven over night to dry.

14. Repeat steps 5 through 13 for each of the remaining test specimens.

15. Determine the weight (Wtin+dry soil) of the tin and dry soil for each test specimen.

Calculations

Moisture Content

dry sampleWeight of

water Weight ofontent Moisture c , or

100

tindrysoil tin

drysoil tin soil tin

W W

W W w (3)

Moist Unit Weight

mold volume of

moist soil weight ofweight Moist unit , or

V W W 12 (4)

Dry Unit Weight

mold volume of

dry soil weight ofeight Dry unit w , or





1001

wd

(5)

Plot the compaction curve, d vs. w. Draw a best-fit curve, using a French curve so the curve

is smooth. Determine the optimum water content and maximum dry unit weight from the

curve.

Plot the zero air voids curve on the same plot as the compaction curve. Use a French curve

and plot at least 4 points to get the general shape of the curve. Plot the Zero Air Voids

Curve:

1001 s

w s

d wG

G

(6)





California State University, Fullerton

Department of Civil and Environmental Engineering


Modified





LABORATORY CONSOLIDATION TEST

Application

Settlement problems are actually two problems in one. Both the magnitude of

settlement and time rate at which this process occurs must be estimated on the

basis of laboratory tests. This laboratory will focus on the time rate of settlement

as it is often the most important aspect of the problem. This lab also focuses on

the pressure-settlement relations.

For instance, suppose it is proposed to build a highway embankment over soft soils.

The embankment places a load on the soil and depending on the thickness of soft soil

and size of the loaded area, the total magnitude of settlement computed may take

many tens of years to occur. Thus the project must wait for the settlement to

occur before construction of pavement sections can take place. There aretechnologies available that can speed up the rate of consolidation. These are

discussed in courses on Ground Modification .

Recall that a complete consolidation test involves loading a soil specimen in a series

of increments. From these data, a void ratio (e ) vs. log pressure curve is developed

and estimates of the total magnitude of settlement are made using the parameters

C c , C r and ’ p . Estimates of the time rate of settlement are made using the

Coefficient of Consolidation, C v , that is interpreted from plots of dial gage reading

(compression) vs. log time during individual load increments of a consolidation test.

C v is not a constant but varies with applied stress. As the stress level increases, the

void ratio decreases and permeability decrease thereby increasing the time required

for water to flow from the soil voids. Therefore, in an actual project, C v should beestimated for the actual range of effective stress expected in the field.

Equipment

Consolidometer set

Filter paper

Stop watch

Balance sensitive to 0.01 lb

Moisture cans

Drying oven

Procedure

You are provided with a trimmed soil specimen.

Measure height of specimen (Subtract the gap between top of the ring and

specimen) .

Take weight of the specimen with ring.





Set a lower porous stone in the consolidometer. Set a filter paper on it. Then set

the soil specimen into the consolidometer. Set a filter paper and upper porous stone

on top of the specimen.

Set the upper platen on top of the porous stone.

Pour water from outer jacket and saturate the specimen for about 15 minutes. This

water level should be kept higher than the porous stone during the test.

Set a steel ball on top of the upper platen and the loading device on top of the ball.

All equipment are set with vertical displacement transducers. Record the initial

LVDT reading for your equipment.

Apply load to the specimen which will give vertical stress of about 7 psi.

Record the deflection dial gauge reading at 0 min, 0.25 min, 1 min, 2 min, 4 min, 6

min, 9 min, 12 min, 20 min, 25 min, 36 min, 60 min, 120 min, 240 min, 480 min, and

1440 min.

Increase the load to about 14 psi, and 28 psi, 56 psi, and 112 psi in every 24 hours

and repeat the same procedure. But just take the reading at 0.25 and 1440 minutefor those readings.

Next Thursday, increase the load to 222 psi and record the deflection at 0 min,

0.25 min, 1 min, 2 min, 4 min, 6 min, 9 min, 12 min, 20 min, 25 min, 36 min, 60 min, 120

min, 240 min, 480 min, and 1440 min.

After that reduce the load slowly and record deformation during unloading at the

end of 112 psi, 56 psi, 28 psi, 14 psi, and 7 psi.

You don’t need to note down intermediate values for the vertical loads other than 7

psi, and 224 psi. For other loads, just note the initial and final deflection.

Remove the soil specimen after 24 hours of the application of the vertical stress of

224 psi and measure final height of the specimen. Measure the weight of the specimen and put the entire specimen into the oven and

oven-dry them for 24 hours. Measure the weight after 24 hours. That will help you

to get void ratio.

Calculations

The lab reports shall include the following:

Sample calculations.

A plot of settlement versus the logarithm of time for the vertical stress of 7 psi

and 222 psi. Calculate settlement amount and time for 50% consolidation. Calculate

time for 50% consolidation.

A plot of settlement vs. square root of time for the vertical stress of 7 psi and 222

psi. Calculate settlement amount and time for 50% consolidation. Calculate time for

90% consolidation.





Determine the coefficient of consolidation, C v from the time rate data collected in

the lab. The calculations are presented below and most textbooks cover this in

detail.

Using the settlement data for 100% consolidation, calculate the void ratio (e) for

the corresponding stresses.

Plot a e-log ' graph and find out the pre-consolidation pressure.

EQUATION TO BE USED

w s

s

s AG

M H

(1)

s

s

H

H H e

0 (2)

Where,

Hs = Height of soil solidMs = Dry mass of the specimen

A = Area of the specimen

Gs = Specific gravity of the soil solid (take 2.68)

w = Density of water

H = Initial height of the specimen

e0 = Initial void ratio

For the first incremental loading, s H

H ee 1

01

(3)

Likewise for the second load increment, s H

H ee

202

(4)

Shown in figure 1 is an example of e-long curve.





Determination of preconsolidation pressure ( ’p or P’p)

Figure 2 Method to determine pre-consolidation pressure

Figure 1 e-log curve





Choose by eye the point of minimum radius of curvature on the e-logσ curve (point

A).

Draw a horizontal line through point A.

Draw a line tangent to the curve at point A.

Bisect the angle made by steps 2 and 3.

Extend the straight line portion of the virgin compression curve

up to intersect the bisecting line from step 4.

The intersection point gives the best estimate of preconsolidation pressure.





ONE-DIMENSIONAL CONSOLIDATION TEST (ASTM D2435)LABORATORY DATA SHEET


Specimen prepared by: Date:

Lab partners/organization: USUFClient: CSUF Project: EGCE 324L



Soil description:

II. TEST DETAILS

Load frame type/serial no.:


Consolidation ring diameter: Initial specimen height, H o :

Consolidation ring mass: Specimen volume, V o :

Specific gravity of soil solids, G s : (take 2.68)



Before Test After Test

Mass of moist soil + porous stone +Ring

Mass of moist soil M To = M Tf =

Mass of porous stone + Ring

Mass of dry soil M d = M d =

Mass of moisture

Moisture content w o = w f =

Void ratio e o = e f

=

Degree of saturation S o = 100% S f = 100%

IV. TEST DETAILS


Load no.: Load increment, ’ :

Filter paper type:

Porous stone type, weight and thickness:

Machine deflection:

Deformation indicator type and conversion factor K (if applicable):






ONE-DIMENSIONAL CONSOLIDATION TEST (ASTM D2435)

TIME-DEFORMATION MEASUREMENTS


V. MEASUREMENTS AND CALCULATIONS ’ = 7 psi

Date

(mm/dd/yy)

Clock Time

(hh:mm:ss)

Elapsed Time

(min)

Raw Deformation( )

Deflection-CorrectedDeformation

( )

0.0

0.25

1

2

4

6

9

12

20

25

36

60

120

240

480

1440

’ = 14 psi

0.25

1440

’ = 28 psi

0.25

1440





V. MEASUREMENTS AND CALCULATIONS

Date

(mm/dd/yy)

Clock Time

(hh:mm:ss)

Elapsed Time

(min)

Raw Deformation( )

Deflection-CorrectedDeformation

( )

’ = 56 psi

’ = 112 psi

’ = 224 psi

0.0

0.25

1

2

4

6

9

12

20

25

36

60

120

240

480

1440

Deformations while reducing load: 112 psi 56 psi 28 psi

14 psi 7 psi





ONE-DIMENSIONAL CONSOLIDATION TEST (ASTM D2435)TIME-DEFORMATION PLOTTING USING THE LOG TIME METHOD

I. TEST DETAILS

Load no.: Load, ’ :

Initial specimen height, H o : Deflection units:Dial gauge conversion factor, K :


II. MEASUREMENTS AND CALCULATIONS CALCULATION SPACE:

’ : d 100:

t 2: d 2:

t 1: d 1:

d: d o:

d 50: t 50:

H D50: cv:

III. EQUATIONS

From figure 3,t 1 = t 2/4 d = d 2 – d 1 d 0 = d 1 – d d 50 = (d 0 + d 100)/2

2

) K ( d H H 50o

50 D

or2

5050

d H H o

D

50

250 )0.197(

t

H c D

v

Time, t (log scale)

D e

f o r m a t i o n

, d

d 100

t 2t 1

d 0

d 1

d 2

d

d d 50

t 50

Figure 3 Deformation-Log time plot for the consolidation data





ONE-DIMENSIONAL CONSOLIDATION TEST (ASTM D2435)TIME-DEFORMATION PLOTTING USING THE ROOT TIME METHOD

I. TEST DETAILS

Load no.: Load, ’ :Initial specimen height, H o : Deflection units:

Dial gauge conversion factor, K :


II. MEASUREMENTS AND CALCULATIONS CALCULATION SPACE:

’ : d 0:

X : 1.15X :

d 90: t 90:

d 100: H D50:

cv:

III. EQUATIONS

From figure 4,

)(11.1 900100 od d d d 90

250 )(8480.

t

H c

Dv

D e

f o r m a t i o n

, d

Time, t (minutes; root scale)

x = (linear scale)

0 1 4 9 16 25 36 49 64 81 100 121

0 1 2 3 4 6 7 8 9 10 115

d-t curve

X

1 . 1

5 X

d 0

d 90

t 90

d 100

Figure 4 Deformation-square root of time plot for the consolidation data





ONE-DIMENSIONAL CONSOLIDATION TEST (ASTM D2435)TIME-DEFORMATION PLOTTING USING THE ROOT TIME METHOD

PLOTTING PAPER

Elapsed time t (min)

S e t t l e m e n t S ( d i v i s i o n )

0 1 862 4 4010 907020 30 6050 1008010

1

4

1

2

1

250150 200 300

0 1 2 43 5 6 7 8 9 10 11 12 13 1514 16 17 18 19 20 21 2322cm0 1 2 43 5 6 7 8 9 10 11 12 13 1514 16 17 18 19 20 21 2322cm

D e f o r m

a t i o n (

)





CONSTANT HEAD AND FALLING HEADPERMEABILITY TEST

Permeability is a measure of the ease in which water can flow through a soil volume. It isone of the most important geotechnical parameters. However, it is probably the most

difficult parameter to determine. In large part, it controls the strength and deformation

behavior of soils. It directly affects the following:

quantity of water that will flow toward an excavation

design of cutoffs beneath dams on permeable foundations

design of the clay layer for a landfill liner.

For fine grained soil Falling head permeability test is done, whereas constant head

permeability test is done for the coarse grained soil.

Application Estimation of quantity of underground seepage water under various hydraulic

conditions

Quantification of water during pumping for underground construction

Stability analysis of slopes, earth dams, and earth retaining structures

Design of landfill liner

Equipment

Combination Permeameter assembly

Stop watch

Graduated cylinder (250 or 500 ml)

Balance sensitive to 0.01 lbMoisture cans

Drying oven

Thermometer





Figure 1 Sketch of the combination permeameter

Figure 2 Sketch of the combination permeameter assembly





Figure 3 Sketch of the combination permeameter test: Falling head (left), constant head

(right)

Constant Head Permeability test

Procedure

The following steps are already done:

Mix sufficient water into the sample to prevent segregation of particle sizes during

placement into the Permeameter. Enough water should be added to allow the

mixture to flow freely, forming layers.

Remove both the chamber cap and upper chamber from the unit by unscrewing the

three knurled cap nuts and lifting them off the tie rods. Position one porous stone on the inner support ring in the base of the chamber.

Using a scoop or funnel, pour the prepared specimen into the lower chamber, using a

circular motion to fill the lower chamber to a depth of 1.5 cm. A uniform layer

should be formed.

Use an appropriate tamping device to compact the layer of soil to the desired

density. Repeat the compacting procedure until the sample is within 2 cm of the top

of the lower chamber section.

Replace the upper chamber section, placing the rubber gasket between the chamber

sections. Be careful not to disturb the test specimen. Continue the sample

placement operation until the level of compacted material is about 2 cm below the

rim of the upper chamber. Carefully level the surface of the specimen and place theupper porous stone on it.

Place the compression spring on the porous stone. Replace the chamber cap and

sealing gasket, securing it firmly with the cap nuts. The spring will restrict upward

sample movement.

Measure and record the sample length.

Assemble the constant head funnel, rod and meter stick. Use the rod clamp the

funnel's lower portion.





Adjust the level of the funnel to allow the constant water level in it to remain a few

inches above the top of the specimen.

Connect the flexible tube from the tail of the funnel to the bottom outlet of the

Permeameter. Keep the valves on top of the Permeameter open.

Place a receiver at the top outlet to collect any water that may come out.

If preferred, a piece of tubing may be connected to the outlet, leading the water to

a sink.

Open the bottom outlet valve and allow water to flow into the permeameter.

As soon as water begins to flow out of the top control (deairing) valve, close the

control valve, letting the water flow out the outlet for a time.

Close the bottom outlet valve and disconnect the flexible tubing at the bottom.

Connect the constant head funnel to the top side port.

Open the bottom outlet valve and raise the constant level head (funnel) to a

convenient height to get a reasonable steady flow of water.

Accurately measure the vertical distance between the funnel overflow level and the

chamber outflow level.

Measure and record the length of the specimen, L.

You need to perform the following steps

Allow adequate time for the flow pattern and/or specimen to stabilize.

After equilibrium flow has been established, measure the time taken to have

specified volume of water flowing out. Use a measuring cylinder and a stop watch.

Repeat three or more times, calculating the average time.

Calculations

The lab reports shall include the following: Sample calculations.

Table showing the calculations pertinent to the permeability of the soil.

Average value of permeability

Calculate the void ratio by oven drying the specimen and taking the dry mass.

EQUATION TO BE USED

k =VL

Aht

(1)

Where,

K = Coefficient of permeability

V = Collected volume of water

L = Length of soil column

A = Area of the soil column (31.65 cm2)

h = Head difference

t = Time required to get V volume





Falling Head Permeability test

Procedure

The following steps are already done: Compact the sample in the lower chamber section of the Permeameter, in layers

approximately 1.5 cm deep, to within about 2 cm of the lower chamber rim. Use an

appropriate tamping device to compact the sample to the desired density.

Remove the upper section of the chamber tie rods and place the upper porous stone

on the specimen, securing the upper section of the chamber with spring to the unit.

Measure and record the length of the specimen.

Use the clamp to attach the falling head burette to the support rod. Position the

burette as high as is possible for practicality. Place the meter stick directly behind

the burette, so the height of water in the burette above the chamber outflow port

may be read.

Saturate the specimen, following the steps outlined above. Measure the heights of the two levels from the outflow level.

You need to perform the following steps

After a stable flow has been established, note the drop in head (h) in 2 hours. (use

a stop watch).

Calculations

The lab reports shall include the following:

Sample calculations.

Table showing the calculations pertinent to the permeability of the soil.

Average value of permeability

Calculate the void ratio by oven drying the specimen and taking the dry mass.

EQUATION TO BE USED

k =At

aLln

1

0

h

h (2)

Where,

K = Coefficient of permeability

a = Area of the burette (1.695 cm2)

L = Length of soil column

A = Area of the soil column (31.65 cm2)

h0 = Initial height of water

h1 = Final height of water = h0 - h





t = Time required to get head drop of h

Temperature Correction

C

C T

C T C k k

20

20

(14)

Where,

kToC = measured permeability at the actual water temperature in the lab

k20oC = permeability at the standard temperature of 20OC

Table 1 of Correction Factors for Water Temperature

Test Water

Temperature, T (C)

T C/20C Test Water

Temperature, T (C)

T C/20C

15 1.135 22 0.953

16 1.106 23 0.931

17 1.077 24 0.91018 1.051 25 0.889

19 1.025 26 0.869

20 1.000 27 0.850

21 0.976 28 0.832

29 0.814

Table 2 Typical permeability coefficients for different soils

Soil Type Typical Permeability, k (cm/sec)

Gravels and Coarse Sands > 10-1

Fine Sands 10-1 to 10-3

Silty Sands 10-3 to 10-5

Silts 10-5 to 10-7

Clays < 10-7





HYDRAULIC CONDUCTIVITY OF GRANULAR SOIL

UNDER CONSTANT HEAD (ASTM D2434)

LABORATORY DATA SHEETI. GENERAL INFORMATION

Tested by: Date tested:Lab partners/organization:

Client: Project:

Boring no.: Recovery depth:

Recovery date: Recovery method:

Soil description: Sand

II. TEST DETAILS

Specimen diameter, D: 6.35 cm Specimen area, A: 31.65 cm

Specimen Length, L: Volume of soil, V:

Dry mass of soil, M s: Specific gravity of soil solids, G s: 2.65 Dry unit weight, d : Void ratio, e:


Saturation method: Constant head Saturation duration: 48 hours

Specimen preparation method: Dry packing



Test

No.

Head

Difference

h)

Hydraulic

Gradient

(i)

Flow

Volume

(Q)

Time

(t)

Flow Rate

(q)

Hydraulic

Conductivity

(k)





HYDRAULIC CONDUCTIVITY OF GRANULAR SOIL

UNDER FALLING HEAD



Tested by: Date tested:Lab partners/organization:

Client: Project:

Boring no.: Recovery depth:

Recovery date: Recovery method:

Soil description: SM

II. TEST DETAILS

Specimen diameter, D: 6.35 cm Specimen area, A: 31.65 cm

Burette area, a: 1.695 cm2 Specimen length, L:

Dry mass of soil, M s: Volume of soil, V:

Specific gravity of soil solids, G s: 2.68 Dry unit weight, d :Void ratio, e: Scale type/serial no./precision:

Saturation method: Constant head Saturation duration: 48 hours

Specimen preparation method: Dry packing

Notes and observations:


Test No. Initial

Head

(H 0 )

Initial Hydraulic

Gradient

(ii)

Final

Head

(H 1 )

Time

(t)

Hydraulic

Conductivity

(k)





CALCULATION OF SEEPAGE DISCHARGE AND SEEPAGE PRESSURE

Seepage discharge calculation

1. Sketch the coffer dam on scale.

2. Measure head difference (H).

3. Make flow net.

4. Find nf and nd from flow net.

5. Calculate seepage discharge

Q = b H

n

nk

d

f .. b = width of channel = 56 cm

For calculation, consider H = 20 cm.

Blowout of Coffer dam

Figure 1: Schematic diagram showing liquefaction potential zone

1. Calculate submerged unit weight of soil, ’.





w s

e

G ).

1

1('

Take Gs = 2.65, e = 0.81

2. Calculate critical gradient, ic.

w

ci

'

3. Calculate head right at the bottom (A) and at D/2 distance from point A of the pile.

(D is the depth of the pile).

HA = ( H – ndA x H) HB = ( H – ndB x H)

ndA = number of head drops at A, H = head drop for each equi-potential line = H/nd

You get values in terms of H

4. )(2

1 B Aaverage H H H

5.

D

H i

average

6. In order to blowout the dam, i = ic

Calculate H for blowout with this.





Seepage

Darcy’s law is applicable when flow of water is in one direction. In real world problems,

seepage occurs in all three dimensions. Solution for 3D problems is complicated and needs

advanced mathematical calculations. In many cases, 3D problems are simplified to 2D andseepage flow is calculated accordingly.

Equation of 2D Steady Flow

Conditions:

Darcy’s law is valid

K is same in all dimensions (homogenous material)

Figure 1 Flow through a 2-D system

Let’s consider a 2-D seepage flow system as shown in figure 1.

Darcy’s Law explains: Aik Q ..

At section X (for 1 m. strip), At section X+dX

1... dyik q x x 1... dyik q dx xdx x

At section Y (for 1 m. strip), At section Y+dY

1... dxik q y y 1... dxik q dy ydy y

As the flow is steady, net flow should be 0.

0)()( x ydx xdy y qqqq





or 0)....()....( dxik dyik dxik dyik y xdy ydx x

or 0).().( dxiidyii ydy y xdx x (1)

But

x

hi x

and

y

hi y

dx x

iii x

xdx x .

and dy

y

iii y

ydy y .

Substituting these values in equation (1)

0....

dxdy

y

idydx

x

i y x

Or 0)()(

y

h

y x

h

x

Therefore, 02

2

2

2

yh

xh (2)

This equation is called Laplace Equation.

Solution for Laplace equation:

Analytical method (mathematical)

Numerical method (Finite Element, Finite Difference)

Flow models (sand, glass bead)

Analog model (electric, heat)

Graphical method (flow net)

Graphical method is discussed in this chapter.

Graphical Solution (Flow Net)

It is quick and simple.

No special equipment is needed.

Drawing improves understanding.

However, for complex problems, finite element is better.

Laplace equation requires 2 families of curves that meet at right angle. One is called flow

line and the other is called equi-potential line . The network of these lines is called “Flow

Net ” (figure 2).

Properties of flow net

Same flow quantity (q) through each flow channel.





Same head drop (h) between each adjacent pair of equi-potential lines

(except for partial drop).

Figure 2 Example of flow net beneath a dam structureIn figure 2,

f n

qq (3)

d n

H h (4)

Seepage Calculation Using Flow Net

If our flow nets are going to have the properties of the lines mentioned above, we need

to draw them in a certain way.

Figure 3 Distribution of equi-potential lines in a flow channel

From figure 3,

Aik q .. = 1... bl

hk

=

l

bhk ..





q and h should be the same for every element. Then,l

bmust also be the same for every

element.

l

b = side length ratio (same for all elements)

orl

b

n

H k

n

q

d f

..

Therefore,l

b

n

n H k q

d

f ...

i.e.l

b H k q .$.. (5)

where,d

f

n

n$

However, if we can makeb

l = 1 by making square flow net grid,

.$. H k q (6)

and Q = q. L

where, L is the length of dam in a perpendicular direction

Method of Drawing Flow Net

Identify boundaries

upstream and downstream surfaces are equi-potential lines as they

represent atmospheric pressure. Therefore, all flow lines intersect

them at right angle.

Body of impervious layer is a flow line, and equi-potential lines

intersect them at right angle.

Sketch 2 – 3 flow channels.

Sketch equi-potential lines.

Iterate, erasing and re-sketching lines to form “square” with l/b = 1. If

required check the square pattern by drawing a circle.

Perform seepage computation for q and then calculate Q.

Shown in figure 4 is an example of flow net under a sheet pile.





Figure 4 Example of flow net and seepage calculation.

Note

For y x k k ,

we make horizontal scale = x

y

k

k x vertical Scale

and plot the structure. Then we follow the same procedure. This gives,

d

f

y xn

n H k k q

...

Use of Flow Net

Uplift pressure under hydraulic structure

From figure 5,

nd = 7 H = 7 m

Head Loss at each equi-potential line = 7/7 = 1 m

Head at A, i.e. hA = (9 – 1 x 1) = 8 m

Uplift pressure UA = 8. w





Likewise, UB = 7. w

Figure 5 Calculation of uplift pressure

Method to determine pore pressure and uplift pressure Determine head at point where pore pressure is required.

Express the head as a value referred to the point itself as a datum.

Calculate pore pressure, UA = hA . w

Caution:

Most common mistake is to be inconsistent about datum.

Head = ( a value ) (referenced to) ( a datum )

To calculate a pore pressure, the best datum from the head is the point itself.

Count head either to head water or to tail water.

Effective stress = ’ = - u

If u = , ’ = 0 (We will have liquefaction )

At liquefaction, = uA

’. Z = i . w . Z





Therefore,w

w s

w

e

G

i

1

)1(

' =

e

G s

1

1

This is called critical gradient (ic)

e

Gi sc

1

1 (7)





11. Write a report based on the differences between the calculated seepage, head

to blowout the cofferdam, equi-potential line and flow net. Write your comment.

CalculationsAll pertinent calculations were supplied last week.

Seepage Discharge from one side2

1

Time

Volume Measured





SEEPAGE INTO A DOUBLE WALLED COFFERDAM

Group:

Date:

A) Initial Head Difference cm

B) Seepage Quantity

Quantity Time (minute)

1.

2.

3.

4.

C) Head drop in equi-potential line

Point 1 cm

Point 2 cm

Point 3 cm

D) Blow out

Total head difference for blowout cm





Measurement of Shear Strength Parameter of Soil with

irect Shear Test

Figure 1 Direct Shear Device

Advantages of Direct Shear Test

Simple, fast

Disadvantages of Direct Shear Test Cannot control pore pressures. Therefore tests are assumed to be drained.

Failure on horizontal plane only, which may not be the weakest plane.

Non-uniform stress conditions inside shear box.

Principal stress rotations occur

Vertical and horizontal stresses are principal stresses before shear.

Vertical and horizontal stresses are not principal stresses at failure.





Figure 2 Shear Strength Envelop

ApplicationDirect shear test gives shear strength parameters (cohesion and friction angle) of

soil. Shear strength parameters are important in all types of geotechnical designs

and analyses.

Equipment

Strain controlled direct shear device with two displacement LVDT and a load cell

Balance sensitive to 0.1 g

Moisture cans

Oven

Procedure

1. Take the shear box, and set two vertical pins to keep the two halves of the

shear box together.

2. Set a porous stone at the base and fill the box with the dry sand (make 1 inchthickness). Compact the sand gently.

3. Set another porous stone on the top.

4. Set top platen on top of the porous stone.

5. Put the shear box assembly into the direct shear device.

6. Fill up the outer jacket with water.

7. Turn on the software and follow the instruction.

8. Apply dead load to the load hanger to make normal stress of approximately 50

kPa. You need to hold the cross bar to make it rest right on top of the top platen.

9. Remove both vertical pins.

10. Set up the dial gauges for vertical displacement and horizontal displacement.

Make sure that the shear box is connected to the electricity line and is on.11. Consolidate the specimen for 100% consolidation and apply horizontal load to the

box at the strain rate that is calculated based on the consolidation data. Set

that speed both in the computer and the shear box.

12. Record horizontal displacement, vertical displacement, and shear force at 15

seconds interval.

13. Shear stress increases, peaks and then drops or may remain flat. Once peak/or

maximum shear stress is attained, continue for a while and stop the test. Be

cautious not to let the shear box touch the wall of water jacket.

14. Take the sample out, take weight and put it into the oven to measure the water

content.

15. Take another specimen and repeat the procedure for the normal stress of 100kPa.

16. Take the third and fourth specimens and repeat the procedure for the normal

stresses of 150 kPa and 200 kPa respectively.

Calculations

17. Calculate area and volume of the specimen.

18. Calculate bulk unit weight of the specimen.





Bulk unit weight ()=V

W

19. Calculate dry unit weight of the specimen.

Dry unit weight(d) = w1

20. Calculate initial and final void ratio.

e = 1d

w sG

take Gs = 2.65

21. Calculate normal stress (’)

Area

Load Normal '

22. Calculate shear stress.

Area

ForceShear

23. Plot versus shear strain (shear displacement/original height of specimen).

24. Plot vertical strain (displacement/initial height) vs shear strain.

25. Plot normal stress (in x-axis) vs shear stress for all tests.

26. The equation of the best fit line will give you c’ and ’.

Report

1. Submit all pertinent calculations and graphs.

2. Report the values of c’, and ’ based on four shear tests.

3. Present final void ratio vs shear stress ratio (/’).






Direct Shear Test Laboratory Data Sheet



Lab partners/organization:Client: CSUF Project: 324 Lab Direct Shear

Boring no.: NA Recovery depth: NA

Recovery date: NA Recovery method: NA

Soil description: Clean sand

II. TEST DETAILS

Sample length/width: 4 in. Sample Height:

Initial Sample Mass: Final Sample Mass:

Wet Mass of the Specimen: Dry Mass of Specimen:

Normal force, N : Normal stress, :

Deformation rate: Deformation indicator type: LVDTShear force measurement instrument type: Load cell

Horizontal dial gauge conversion factor, K H : 1

Vertical dial gauge conversion factor, K V : 1

Proving ring dial gauge conversion factor, K F : 1


Horizontal

Deformation

Reading

(GV )

Vertical

Deformation

Reading

(G H )

Force

Reading

(G F )

Horizontal

Displacement

(H)

Vertical

Displacement

(V )

Shear

Force

( F )

Shear

Stress

( )

Shear strength ( f ):





Measurement of Shear Strength of Soil withUnconfined Compression Test

Shear Strength of Soil Shear strength of soil is the internal resistance of soil to shearing forces.

Determination of the shear strength of soil is one of the most important aspects of

geotechnical engineering. Ultimate shear strength and the deformation behavior of

soil under an applied load are critical for design of foundations, earth structures,

retaining structures, and many others. Shear strength is fundamentally due to the

combination of friction between particles and the work required to cause the sample

to change in volume, or: 1) Inter-granular friction, , and 2) Dilation, or volume

change, . Naturally, any factor which influences friction or volume change will

influence the strength of a specimen. The most influential factors (state

parameters) that affect volume change include void ratio and confining stress ( 3 ’).Grain shape and roughness are two factors that influence friction.

Shear strength at failure is normally defined by Mohr-Coulomb Failure criteria.

Mohr-Coulomb Failure criteria

Material fails with the combined effect of normal stress (n’) and shear stress ().

According to Mohr,

f = f ()

Figure 1 Mohr-Column Failure Envelope

In most of the soil mechanics problems, failure envelope is considered as a straight line,

given by the equation,





tann failure c

Where,

c is the cohesion

is the angle of friction.

n is the normal stress on the failure plane at failure.

This equation is called Mohr-Coulomb Failure Criteria.

The strength parameters c’ and ’ are determined from the slope and intercept on a Mohr

diagram of a best-fit line tangent to a series of Mohr circles at failure. The influence of

inter-granular friction, dilation, and true cohesion are assumed to be represented by these

two parameters.

In saturated soil, = ’ + u and

'tan'' n failure c

Where,

c’ is the effective stress value of cohesion (very small)

’ is the effective stress (or drained) angle of friction.

’ n is the normal stress on the failure plane at failure.

Table 1 Typical values of drained angle of internal friction angles for sands and silts





For sand and gravel, c’ = 0 (they are called cohesionless soil)

For normally consolidated and remolded clays, c’ = 0

For over consolidated clays, c’ = f (OCR)

Below the shear envelope - failure does not occur

At and above shear envelope - failure occurs

Inclination of Plane of Failure

Here, 1’ = Major principal stress

3’ = Minor principal stress

We can draw Mohr circle for the stress condition shown above as shown in the figure 3.

Figure 2 Stress systems in a soil mass





Figure 3 : Failure envelope developed from the Mohr Circle

Let’s extend failure envelope to touch the x-axis at f.

Then, at a plane inclined at an angle of from major principal axis,

’ + 900 = 2

Therefore,2

450

From figure,

)

2

'45tan('2)

2

'45(tan'' 002

31

c

Here, c’ and ’ are the effective shear strength parameters.

For earth structures and soil-structure interaction (foundations) the Factor of

Safety against failure is given by:

ss to soil Shear stre

f soil Strength o FS

Determination of Shear Strength

Shear strength of soil can be measured in laboratory or in-situ.

Laboratory Measurement

There are different methods to measure shear strength of soil in laboratory.

a. Direct Shear Test

b. Triaxial Shear Test

c. Unconfined Compression Test

d. Simple Shear Test





e. Ring shear device

Figure 4 : Sketch of an unconfined compression test device





Unconfined Compression Test

ApplicationUnconfined compression test gives shear strength of soil. Shear strength is

important in all types of geotechnical designs and analyses.

EquipmentStrain controlled unconfined compression test device

Scale


Moisture cans

Oven

Procedure

1. Get three trimmed soil specimens provided to you.

2. Measure the dimensions of the specimen (diameter and length).

3. Measure the weight of the specimen.

4. Load the samples into the unconfined compression device. They should be placed

in between two platens.5. Lower the upper platen slowly (or raise the lower platen depending upon the

machine), just to make contact with the top of the soil specimen.

6. Set the vertical displacement dial gauge and loading proving ring dial gauge to

zero.

7. Lower the upper platen (or raise the lower platen) at the speed of 0.5%/min.

8. Record the load and displacement dial gauge readings at every 5 or 10 seconds

depending on the type of the soil. Usually the readings are taken at every 0.01

inch of displacement.

9. The compression load goes on increasing, peaks, and then decreases.

10. After it starts to decrease, stop the test.

11. Reverse the platen movement, and remove the specimen.12. Draw a free hand sketch of the specimen after failure.

13. Determine the moisture content of the specimen.

14. Repeat this procedure for two more specimens.

Calculations

15. Calculate axial strain. = L

L

L = Vertical deformation of the specimen.

16. Calculate vertical load on the specimen.

Vertical load = Load cell reading x 1 Lb

17. Calculate the corrected area of the specimen (Ac)

1

0 A Ac

A0 = Initial cross-sectional area i.e. x D2/4

18. Calculate the stress on the specimen.

c A

Load





19. Plot versus axial strain. Peak is qu. Then calculate su.2

uu

q s

Figure 5 Stress-strain curve and Mohr circle generated from UC Test

Table 2 Relationship between consistency and UC strength






Unconfined Compression Test Laboratory Data Sheet



Lab partners/organization:

Client: USUF Project: 324L



Soil description:

II. TEST DETAILS

Initial specimen diameter, Do: Initial specimen area, Ao:

Initial specimen length, Lo: Initial specimen volume, V o:

Moist mass of specimen, M : Dry mass of specimen, M s:Moisture content, w: Total unit weight, : Dry unit weight, d :

Specimen preparation method: Hand Compaction

Deformation indicator type: Dial gauge Axial strain rate, 1/t :

Deformation dial gauge conversion factor, K L: x10-3 in

Force measurement instrument type: Load cell

Proving ring dial gauge conversion factor, K P : 1 lb


Deformation

Reading

(G L)

Axial

Deformation

( L)

Load

Reading

(G P )

Axial

Load

( P )

Axial

Strain

( 1)

Corrected

Area

( A)

Axial

Stress

( )

EQUATIONS:

1 = L/Lo

A = Ao/(1- 1)

1 = P / A

L = G L K L

P = G P K P

su = qu/2





Unconfined compressive strength, qu:

Undrained shear strength, su:









Lab partners/organization:Client: USUF Project: 324L



Soil description:

II. TEST DETAILS



Moist mass of specimen, M : Dry mass of specimen, M s:

Moisture content, w: Total unit weight, : Dry unit weight, d :

Specimen preparation method: Hand CompactionDeformation indicator type: Dial gauge Axial strain rate, 1/t :





Deformation

Reading

(G L)

Axial

Deformation

( L)

Load

Reading

(G P )

Axial

Load

( P )

Axial

Strain

( 1)

Corrected

Area

( A)

Axial

Stress

( )



EQUATIONS:

1 = L/Lo

A = Ao/(1- 1)

1 = P / A

L = G L K L

P = G P K P

su = qu/2





UU Triaxial Test

Concept of Shear Strength

Please refer the same materials you got in Unconfined Compression test.

a. Triaxial Shear Test





b. Triaxial test is more reliable because we can measure both drained and

undrained shear strength.

c. Generally 1.4” diameter (3” tall) or 2.8” diameter (6” tall) specimen is

used.

Figure 1 triaxial compression testing device





d. Specimen is encased by a thin rubber membrane and set into a plastic

cylindrical chamber.

e. Cell pressure is applied in the chamber (which represents 3’) by

pressurizing the cell fluid (generally water).

f. Vertical stress is increased by loading the specimen (by raising theplaten in strain controlled test and by adding loads directly in stress

controlled test, but strain controlled test is more common) until shear

failure occurs. Total vertical stress, which is 1’ is equal to the sum of 3’

and deviator stress (d).

g. Measurement of d, axial deformation, pore pressure, and sample volume

change are recorded.

h. Depending on the nature of loading and drainage condition, triaxial tests

are conducted in three different ways.

i. UU Triaxial testii. CU Triaxial test

iii. CD Triaxial test

In this lab, we will conduct UU triaxial test.





Unconsolidated Undrained Triaxial Test (UU Triaxial Test) As drainage is not permitted and consolidation is not necessary, this test is very

quick, and also referred as Q-test.

As drainage is not permitted, u increases right after the application of 3’ as well as

after the application of d.

As Uc = B. 3 and Ud = A . d

Total u = B. 3 + A . d

u = B. 3 + A . (1 - 3)

This test is common in clayey soils.

ApplicationUU triaxial test gives shear strength of soil at different confining stresses. Shear

strength is important in all types of geotechnical designs and analyses.

Equipment

Strain controlled triaxial load frame

Triaxial cell assembly

Cell pressure supply panel

Scale


Moisture cans

Oven

Procedure (Follow the specific guideline provided in a separate sheet)

Measure diameter, length, and initial mass of the specimen.

Measure the thickness of the rubber membrane. Set a soil specimen in a triaxial chamber.

Increase the cell pressure to a desired value (70 kPa for the first case and 140 kPa

in the second case).

Shear the specimen at the rate of 1%/min or 0.7 mm/min (for 70 mm sample height).

In automated device, the software calculates it automatically based on the soil type.

Record L, and d in every 10 seconds (computer does it automatically).

Continue the test until the deviator stress shows ultimate value or 20% axial strain.

After completion of the test, release the cell pressure to 0, vent the pressure and

bring the cell down by bring the lower platen down, drain the cell, and clean theporous stone and the assembly.

Sketch the mode of failure.

Measure the weight of the soil specimen again, and put the specimen into the oven.

Measure the weight again after 24 hours.

Repeat the test for the second specimen too (140 kPa of cell pressure and third

specimen 210 kPa of cell pressure).





Calculations

Calculate axial strain. = L

L

L = Vertical deformation of the specimen.

Calculate vertical load on the specimen.

You will get it directly from the force transducers.

Calculate corrected area of the specimen (Ac)

1

0 A Ac

A0 = Initial cross-sectional area i.e. x D2/4

Calculate the stress on the specimen.

c A

Load

Plot d versus axial strain separately for three tests. Plot d vs a for three tests in the same plot.

Plot Mohr circle based on 1 and 3 at failure. They should give the same d value.

Add one Mohr circle for unconfined compression test too (That you did last week).

Make a straight line, which is tangent to all Mohr’s circles. This gives cu with a

horizontal line, i.e. u = 0. Therefore this test is called = 0 test.

2

d uc

Calculate the moisture content of the specimen after the test.

Calculate the initial void ratio of the specimen (Use the equations provided in the

earlier classes).

Figure 2 Total stress Mohr circle and failure envelope obtained from UU triaxial test





UU Triaxial Test Laboratory Data Sheet



Lab partners/organization:Client: CSUF Project: Soils Lab


Recovery date: Recovery method: N/A

Soil description:

II. TEST DETAILS



Moist mass of specimen after test, M : Dry mass of specimen, M s:

Moisture content, w: Total unit weight, :

Dry unit weight, d : Degree of saturation, S :Membrane type: Standard Rubber Membrane Axial strain rate, 1/t :

Deformation indicator: LVDT Force indicator: LVDT

Cell pressure, 3: Specimen preparation method: Hand Compaction



Axial

Deformation

( L)

Axial

Load

( P )

Axial Strain

( 1)

Corrected

Area

( A)

Deviator

Stress

( )

EQUATIONS:

a = L/Lo

A = Ao/(1- a)

= P / A

1f = 3 + f

3:

f : 1f :







Lab partners/organization:

Client: CSUF Project: Soils Lab

Boring no.: N/A Recovery depth: N/ARecovery date: Recovery method: N/A

Soil description:

II. TEST DETAILS



Moist mass of specimen after test, M : Dry mass of specimen, M s:

Moisture content, w: Total unit weight, :

Dry unit weight, d : Degree of saturation, S :

Membrane type: Standard Rubber Membrane Axial strain rate, 1/t :

Deformation indicator: LVDT Force indicator: LVDT

Cell pressure, 3: Specimen preparation method: Hand Compaction



Axial

Deformation

( L)

Axial

Load

( P )

Axial Strain

( 1)

Corrected

Area

( A)

Deviator

Stress

( )

EQUATIONS:

a = L/Lo

A = Ao/(1- a)

= P / A

1f = 3 + f

3:

f :

1f :





USER’S GUIDELINE FOR THE ELE TRIAXIAL DEVICE

(UU TRIAXIAL TEST)

POWER AND MAIN SUPPLY SETTINGS (This step is

already done)

1. Press the “Power Display” power button to the “ON” position. After Stabilization

(approx. 15 min.), push the “Tare” button to zero the display.

2. Turn on the laboratory vacuum supply. The associated amount of vacuum available to

your system will be displayed on the “Vacuum Supply Gauge”.

3. Turn on the laboratory compressed air supply. Viewing the “Pressure Supply” gauge,

adjust the “Master Regulator” until the desired maximum supply pressure is reached.

The displayed pressure should be about 10 psi more than the required cell pressure.

Do Not exceed 150 psi (1034 KPa) pressure.

4. Turn on the laboratory water supply.

FILLING OF THE DE-AIRED WATER TANK SYSTEM (This

step is already done)

1. Turn the “De-Airing Water Control” valve to the “Fill” position.

2. When the tank water level is about 1” from the top, turn the “De-Airing Water

Control” valve to the “vent” position (Very Slowly to allow water to drain).

DE-AIRING THE WATER TANK (This step is alreadydone)

1. Turn the “De-Airing Water Control” valve to the “Vacuum” position.

2. Apply vacuum for 10-15 minutes and, at the same time, gently shake the tank

occasionally to enhance the removal of air from water.

3. Turn the “De-Airing Water Control” valve to the “vent” position.

FILLING THE BURETTE CHANNELS (This step is already

done)

1. Set all five valves on the test cell to the closed position.

2. Set the “De-Airing Water Control” valve to the “Pressure” position.

3. Set the “Burette/Annulus Input Control” valve to the “vent” position.

4. Set the “Annulus Control Switch” to the “open” position (Normal).

5. Slowly turn the “Burette/Annulus Flow Control” valve to the “Fill” position. When the

water reaches the desired level, turn the “Burette/Annulus Flow Control” valve to





the “Cell Operate” position. Do not overfill. Water should not be allowed to flow into

the pressure tube at the top.

6. Repeat the above steps until two burette channels being used are filled to the

desired level.

Note: If the water level in the “De-Aired Water Tank System” drops to about 1” from the

bottom, repeat the filling and de-airing procedures described above.

DE-AIRING THE BURETTE CHANNELS (This step is

already done)

1. Set the “Burette/Annulus Input Control” valve for each channel to the “vacuum”

position. Under normal operating conditions, the de-airing process should be

completed in about 5-10 minutes.

2. After completion, set all “Input Control” valves back to the “vent” position.

F PREPARATION OF THE SAMPLE

1. Trim the sample to be tested using a Miter Box.

2. Measure the height and diameter of the sample at various locations to get an

average value.

3. Measure the weight of the trimmed sample before test.

4. Wrap the sample in a plastic sheeting to prevent any moisture loss.

5. Use the trimmings to get the Moisture Content of the sample before test.

G PREPARATION FOR THE TRIAXIAL LOADING

1. Double click on the software icon “DS7” on the desktop.

2. Click on the button “New Test”.

3. Select “ UU1 --Triaxial Quick Undrained Tests-AS”.

4. Click on the button “Select a Machine for the Test”.

5. Fill in the spaces in this window and click on the button “OK” to the right side of the

screen. The fields marked * by their side can not be left blank and the characters

\ / * . , : ; @ # ~ ? can not be used while filling up the spaces.6. In the window “Tests in Progress” make sure that you select the test that you want

to run and then click on the button “OK” at the bottom of the screen.

7. Switch on the Load cell machine using the button at the back.





H MONITORING THE TEST

1. In the “Test Monitoring” window, make sure that all the test data shown in the

upper left box is correct.

2. Click on the button “Start Test Stage” located to the upper right side of the screen. 3. In the next window select “Test Initialization” and click on button “OK” in the

bottom.

4. In the “Test Initialization” window, enter the previously measured sample Diameter,

weight, and height.

5. The bulk density of the sample will be calculated automatically by the software.

6. The information regarding the Membrane Thickness and Youngs Modulus are default

values and may not be changed, unless using a different kind of membrane around

the sample.

7. After entering all data click on the green button “Confirm Setup Data”.

8. This will bring you back to the “Test Monitoring” window.

9. Again click on button “Start Test Stage” located to the upper right side of thescreen.

10. This time select “Compression” from the menu and then click on button “OK” at the

bottom of the window.

I COMPRESSION STAGE

From the previous stage you will be directed to the screen titled “Compression

Stage for Undrained Test”.

1. Vent Cell Pressure Transducer to Atmosphere and Reset:

a. Set the “Burette/Annulus Input Control” valve to the “Pressure” Position.

b. Set the “Annulus Control Switch” valve to the “on” position.

c. Set the “Burette/Annulus Flow Control” valve to the “Cell Operate” position.

d. Make sure the cell pressure transducer is open to atmosphere and wait for

10 seconds.

e. In the DS-7 software window, click on the red button “Reset Cell Pressure”.

2. Fill and Pressurise Cell. Select Material Type and Press Button to Calculate

Suggested Rate of Strain on Enter Directly:

a. Close the valve on the test cell marked “CP”.

b. Carefully place the sample on the Triaxial cell base pedestal.

c. Place the top pressure pad and use black O-rings to secure the membrane

around the base pedestal and top pressure pad.

d. Place the Triaxial cell cover over the sample and use the three rods to

secure it in place.

e. Open the knob at the top of the glass cylinder and attach the tube marked

“CP” to the knob marked “water” located at the bottom left of the panel.





Open the valve on the test cell marked “CP”. This will gradually fill the cell.

Control the flow using the valve marked CP.

f. Close the knob at the top of the glass cylinder when the cell is filled with

water.

g. Detach the tube marked “CP” from the knob marked “water” and attach it

back to the knob marked “CP” on the panel.

h. Close the valve on the test cell marked “CP”.

i. Use the knob in the “Set Pressure Control” panel to increase the pressure to

the desired cell pressure level. Monitor the cell pressure box in the DS-7

software to get the accurate reading.

j. Set the “Burette/Annulus Input Control” valve to “Pressure” position.

k. Slowly open the valve on the test cell marked “CP”. This will transfer the cell

pressure to the water inside the glass cylinder.

l. In the DS-7 software window, select the right “Material Type” to the right

side of the window and click on the button “Calculate Rate of Strain”.

m. Input the “calculated rate of displacement” value from the computer screen

to the display window at the bottom of the test cell and press Enter ().

3. Calculate Logger Sampling Rates (based on percentage of length of specimen at

failure):

a. On the DS-7 software window, fill up the boxes marked “first increments”,

“upto”, and “second increments”. This is the increment at which the results

will be captured by the transducers. The default values are from the ASTM

Standard. Set both for 0.01%.

4. Reset Force Transducer & Bring Piston just into contact with top cap:

a. Raise the sample using the key on the keypad on the loading frame until

the load piston just touches the top notch of the top plate above the soil

sample.

b. On the DS-7 software window, click on the red button marked “Reset Force

Transducer”.

c. This should reset the lower right window on the “Test Monitoring Window” in

the DS-7 software to 0.0 lbf.

5. Reset Axial Displacement & Start Compression at End of Count Down:

a. Place the “axial displacement transducer” bottom touching the horizontal rod

and click on the button “Reset Axial Displacement Transducer” on the DS-7

software window.

b. This should reset the lower left window on the “Test Monitoring” window of

the DS-7 software to 0.0 inches.

6. Click on the green “Continue” button at the bottom of the page of the software

window.





7. A window will appear that will instruct you to press enter (Green Button) to start

the Test Countdown. If everything is ready, click on the green button “Start Test

Countdown”.

8. Once the two whistles go, press the green button “Run” on the keypad at the bottom

of the test cell.

J TO STOP THE TEST

1. To stop the loading at any time press the red button “Stop” on the keypad of the

load frame.

2. In the DS-7 software, on “Test Monitoring” window click on button “End Test Stage”

3. Click on button “Start Test Stage” button.

4. Select “Final Measurements” and click on OK.

5. Enter all parameters that are available at this time

Final Specimen Weight (wet)Final Specimen Weight (dry)

Initial Moisture Content from Trimmings

Lab Temperature during test

Particle Specific Gravity

6. Click on green button “Confirm Data”.

7. Click “OK” on the window stating “FINAL STAGE IS NOW COMPLETE. PRESS OK

TO STORE THE TEST DATA READY FOR ANALYSIS OR PRESS CANCEL TO

PERFORM FURTHER STAGES”.

8. Save the Raw data obtained from the test to a directory of your choice. The

software will prompt to a default directory.

9. Click on button “exit” to exit from the software.

K DRAINING THE CELL

1. Turn the “set Pressure Control” knob in counterclockwise direction to reduce the

cell pressure.

2. Turn the “Burette/Annulus Input Control” valve to “Bridge Off” position.

3. Open the top knob of the glass cylinder in the load cell assembly.

4. Set the “Burette/Annulus Flow control” to “drain” position.

5. Open the valve on the test cell marked “CP”. This will drain the water from the glass

cylinder.

L DISMANTLING THE CELL

Use the button on the keypad of the load frame to lower the sample away from

the load piston.





Unscrew the three rods from the sides of the glass cylinder and take out the

cylinder.

Dismantle the sample from the test cell and secure the membrane, top and bottom

end plates.





Stability Analysis of Slopes

Background

Evaluating the stability of slopes in soil is an important, interesting, and challengingaspect of civil engineering. Concerns with slope stability have driven some of the

most important advances in our understanding of the complex behavior. Extensive

engineering and research studies performed over the past 70 years provide sound

set of soil mechanics principles with which to attack practical problems of slope

stability. There are a number of methods ranging from very simple to highly

complicated numerical calculation approach, available for the stability analysis of

slopes and a number of computer software are available for the solution. However,

very simple methods that can be accomplished through a simple spreadsheet

programming are still popular. In this class, we will conduct stability analysis for a

slope for steady seepage condition using Ordinary Method of Slice and Bishop’s

simplified method and compare the results.

Simple theory involved in the analysis

Ordinary Method of slice

For the slope shown in the figure 1,

pn

n

nn

pn

n

nnn

s

W

CosW Lc

F

1

1

sin

)'tan'.(

(1)

Simplified Bishop’s Method

Based on the analysis made on the slope element shown in figure 2,

pn

n

nn

pn

n n

nn

s

W

mW Lc

F

1

1 )(

sin

1)'tan'.(

, where (2)

s

n

nn F

m

sin'.tancos)(

bn = width of the slice (We need to perform iteration for this analysis)





Figure 1 Stability analysis by ordinary method of slices

Figure 2 Stability analysis by Bishop’s simplified method





Stability Analysis for Steady-state Seepage

For steady-state seepage, we need to modify equations 1 and 2 to cover the influence of

water.

Equation (1) is modified as,

pn

n

nn

pn

n

nnnnn

s

W

LuCosW Lc

F

1

1

sin

)'tan)('.(

(3)

Equation (2) is modified as

pn

n

nn

pn

n n

nnnn

s

W

m LuW Lc

F

1

1 )(

sin

1)'tan)('.(

(4)

Information needed

Cross-section of slope

Engineering scale

Scientific calculator or computer

Procedure

1. Divide the entire slope into a number of equally spaced (or based on slopes)

slices.

2. Measure the required parameters and populate the excel spreadsheet (shown in

the table below).

3. Calculate factor of safety using the above equations. Compare with two methods.

Figure 3





c w

slice X ys yw yg b hs hw hsave hwave W u Wcos Wsin L U WcosU

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

FS





c w

slice X ys yw yg b hs hw hsave hwave W u Wsin L U WU m Num

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

FS

FS





Slope A

Task:

1. Please calculate the factor of safety of slope A. Consider unit weight of soil as 18 kN/m3, cohesion as 2 kPa, and friction angle as 100.

2. Please also calculate the friction angle to give FS of 1 (Ignore cohesion).

3. Please design countermeasures to increase the factor of safety to 1.5. Examples of countermeasures are: head excavation, toe loading,

lowering ground water table, piling, and drilled shaft.




EGCE 324L (Soil Mechanics Laboratory) Spring 2009

Instructor: Binod Tiwari, PhD

104

Example Problem

Calculate the factor of safety of this slope with both Bishop’s Simplified Method and

Method of Slice.




EGCE 324L (Soil Mechanics Laboratory) Spring 2009


105




EGCE 324L (Soil Mechanics Laboratory) Spring 2009Spring 2007


106

Method of Slice

18 c 0 43 w 10

slice X ys yw yg b hs hw hsave hwave W u Wcos Wsin L U WcosU

1 0 3.67 3.67 3.67 0.00 0.00

2 1.47 2.75 3.67 3.67 1.47 0.92 0.92 0.46 0.46 12.17 -32.04 4.60 10.32 -6.46 1.73 7.98 2.34

3 2.94 2.06 3.67 3.67 1.47 1.61 1.61 1.27 1.27 33.47 -25.14 12.65 30.30 -14.22 1.62 20.54 9.76

4 4.41 1.61 3.67 3.67 1.47 2.06 2.06 1.84 1.84 48.55 -17.02 18.35 46.43 -14.21 1.54 28.21 18.22

5 5.88 1.32 4.40 4.40 1.47 3.08 3.08 2.57 2.57 68.00 -11.16 25.70 66.72 -13.16 1.50 38.51 28.21

6 7.35 1.25 5.28 5.28 1.47 4.03 4.03 3.56 3.56 94.07 -2.73 35.55 93.96 -4.47 1.47 52.32 41.64

7 8.82 1.28 6.09 6.24 1.47 4.96 4.81 4.50 4.42 118.94 1.17 44.20 118.91 2.43 1.47 64.99 53.93

8 10.29 1.47 6.97 7.16 1.47 5.69 5.50 5.33 5.16 140.90 7.36 51.55 139.74 18.06 1.48 76.41 63.33

9 11.76 1.76 7.63 8.07 1.47 6.31 5.87 6.00 5.69 158.76 11.16 56.85 155.76 30.73 1.50 85.18 70.58

10 13.23 2.28 8.15 8.95 1.47 6.67 5.87 6.49 5.87 171.73 19.48 58.70 161.89 57.27 1.56 91.53 70.37

11 14.7 2.94 8.66 9.91 1.47 6.97 5.72 6.82 5.80 180.46 24.18 57.95 164.63 73.91 1.61 93.38 71.25

12 16.17 3.89 9.03 10.79 1.47 6.90 5.14 6.94 5.43 183.50 32.87 54.30 154.12 99.60 1.75 95.04 59.08

13 17.64 5.14 9.47 11.67 1.47 6.53 4.33 6.72 4.74 177.68 40.38 47.35 135.36 115.10 1.93 91.37 43.99

14 19.11 6.79 9.69 11.52 1.47 4.73 2.90 5.63 3.62 148.97 48.30 36.15 99.10 111.23 2.21 79.89 19.21

15 20.58 9.17 9.76 11.52 1.47 2.35 0.59 3.54 1.75 93.67 58.30 17.45 49.22 79.69 2.80 48.81 0.41

16 21.31 11.52 11.52 11.52 0.73 0.00 0.00 1.18 0.30 15.44 72.74 2.95 4.58 14.74 2.46 7.26 -2.68

550.24 26.63 549.62

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

FS 0.93





Bishop’s Simplified Method

18 c 0 43 w 10

slice X ys yw yg b hs hw hsave hwave W u Wcos Wsin L U WU m Num

1 0 3.67 3.67 3.67 0.00 0.00

2 1.47 2.75 3.67 3.67 1.47 0.92 0.92 0.46 0.46 12.17 -32.04 4.60 10.32 -6.46 1.73 7.98 4.19 0.42 9.21

3 2.94 2.06 3.67 3.67 1.47 1.61 1.61 1.27 1.27 33.47 -25.14 12.65 30.30 -14.22 1.62 20.54 12.93 0.57 21.28

4 4.41 1.61 3.67 3.67 1.47 2.06 2.06 1.84 1.84 48.55 -17.02 18.35 46.43 -14.21 1.54 28.21 20.34 0.72 26.24

5 5.88 1.32 4.40 4.40 1.47 3.08 3.08 2.57 2.57 68.00 -11.16 25.70 66.72 -13.16 1.50 38.51 29.50 0.83 33.27

6 7.35 1.25 5.28 5.28 1.47 4.03 4.03 3.56 3.56 94.07 -2.73 35.55 93.96 -4.47 1.47 52.32 41.75 0.96 40.51

7 8.82 1.28 6.09 6.24 1.47 4.96 4.81 4.50 4.42 118.94 1.17 44.20 118.91 2.43 1.47 64.99 53.95 1.02 49.51

8 10.29 1.47 6.97 7.16 1.47 5.69 5.50 5.33 5.16 140.90 7.36 51.55 139.74 18.06 1.48 76.41 64.49 1.09 54.98

9 11.76 1.76 7.63 8.07 1.47 6.31 5.87 6.00 5.69 158.76 11.16 56.85 155.76 30.73 1.50 85.18 73.58 1.14 60.43

10 13.23 2.28 8.15 8.95 1.47 6.67 5.87 6.49 5.87 171.73 19.48 58.70 161.89 57.27 1.56 91.53 80.20 1.21 61.88

11 14.7 2.94 8.66 9.91 1.47 6.97 5.72 6.82 5.80 180.46 24.18 57.95 164.63 73.91 1.61 93.38 87.08 1.24 65.55

12 16.17 3.89 9.03 10.79 1.47 6.90 5.14 6.94 5.43 183.50 32.87 54.30 154.12 99.60 1.75 95.04 88.46 1.27 64.83

13 17.64 5.14 9.47 11.67 1.47 6.53 4.33 6.72 4.74 177.68 40.38 47.35 135.36 115.10 1.93 91.37 86.31 1.28 62.97

14 19.11 6.79 9.69 11.52 1.47 4.73 2.90 5.63 3.62 148.97 48.30 36.15 99.10 111.23 2.21 79.89 69.08 1.26 51.12

15 20.58 9.17 9.76 11.52 1.47 2.35 0.59 3.54 1.75 93.67 58.30 17.45 49.22 79.69 2.80 48.81 44.85 1.20 34.75

16 21.31 11.52 11.52 11.52 0.73 0.00 0.00 1.18 0.30 15.44 72.74 2.95 4.58 14.74 2.46 7.26 8.18 1.06 7.21

550.24 643.74

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

FS, trial 1.17

FS 1.17 5.88





OW MUCH DID YOU LEARN?1. You are supposed to conduct a sieve analysis using the US # 10, #20, #50,

#100, and #200 sieves. What should be the order (sequence) of stacking of

those sieves from the top to the bottom?

a) #200, #100, #20, #50, #10b) #200, #100, #50, #20, #10

c) #10, #20, #50, #100, #200

d) #10, #50, #20, #100, #200

2. Uniformity coefficient of a sand specimen is 2. Out of the total mass, 10% mass

of the soil specimen were finer than 0.2 mm. Calculate the size of the soil

particle (D) in mm for 60% of the soil to be finer than D.

a) 0.4

b) 0.1c) 1.0

d) None of the above

3. Which of the following equipment are used for the measurement of the liquid

limit of soil using the Atterberg’s method?

a) Casagrande’s cup

b) Moisture can

c) Frosted glass plate

d) All of the above

e) (a) and (b)

4. While measuring the liquid limit of a soil specimen, what should be the maximum

size of the soil particle?

a) Particles passing the US #40 sieve

b) 0.425 mm

c) Particles passing through the US #200 sieve

d) (a) and (b)

5. When calculating the liquid limit of a soil specimen, number of cranks is plottedin x-axis and water content is plotted in y-axis. Liquid limit is the water contentfor 25 cranks. How do you plot that graph?

a) x-axis in log scale and y-axis in arithmetic scale

b) both axes in log scale

c) x-axis in arithmetic scale and y-axis in log scale

d) Both x- and y- axes in arithmetic scale





6. While measuring the plastic limit of a specimen, the plastic limit is the moisture

content when soil thread crumbles at,

a) 25 cranks

b) 3.18 mm diameterc) 3.18 inch diameter

d) 20 cranks

7. The plasticity index of a soil is equal to,

a) liquid limit + plastic limit

b) liquid limit – plastic limit

c) plastic limit – liquid limit

d) water content – plastic limit

8.

While measuring the plastic limit of a soil, moisture contents of the specimenwere: 11.63%, 11.64%, 11.65%, and 51.42%. What should be the plastic limit of

the specimen?

a) 11.64%

b) 11.63%

c) 21.58%

d) I would repeat the test

9. For the soil classification system, USCS stands for,

a) Universal Soil Classification Systemb) Universal Soil Classification Service

c) Universal Soil Classification Standardd) Unified Soil Classification System

10. What does the symbol SC stand for in the USCS classification?

a) clayey sand

b) sandy clay

c) clayey siltd) silty clay

11. In a dam, difference between the head and tail water level is H. A square gridflow net is drawn to calculate the seepage discharge. Number of flow channels

was nf and number of equi-potential drops was nd. Coefficient of permeability ofsoil was K and hydraulic gradient was i. What should be the seepage discharge

per unit length of dam?





a)d

f

n

n H K

b)d

f

n

ni K

c) f

d

nni K

d) f

d

n

n H K

12. A cofferdam was made in soil that has specific gravity of 2.7 and void ratio of

0.7. What is the critical hydraulic gradient for that soil?

a) 1.5

b) 0

c) 1

d) 2

13. What is the water content of the soil corresponding to the maximum Proctor

dry density, called?

a) liquid limit

b) maximum water content

c) optimum moisture content

d) shrinkage limit

14. What is the main difference between the Standard Proctor and Modified

Proctor tests?

a) Number of soil compaction layer in the Standard Proctor is 3,

whereas it is 5 in the Modified Proctor

b) Weight of the hammer in the Standard Proctor is approximately

double than that in the Modified Proctor.c) Drop height of the hammer in the Standard Proctor is 1.5 times less

than that in the modified Proctor

d) All of the above

e) (a) and (c)

15. Soil compaction is done to _____________________ .

a) increase the shear strength

b) increase the compressibility

c) increase the permeability

d) all of the above





16. You are conducting a laboratory consolidation test on a 1 inch thick soil

specimen using both-side drainage. It took 24 hours to get 100% consolidation.

How long does it take for a 2 inch thick specimen to get 100% consolidation at

the same drainage condition?

a) 24 hoursb) 48 hours

c) 96 hoursd) 12 hours

17. There are two methods to estimate the coefficient of consolidation of soil in a

laboratory consolidation test. One method plots time in log scale in x-axis and

the other method plots the square root of time in x-axis. Using the square root

of time method, what do you directly calculate from the chart?

a)

t90 b) t100

c) t50 d) t10

18. Conducting a direct shear test, what do you directly measure?

a) c’ and ’

b) cu c) cu and u

d) V and H

19. A sand specimen was loaded in a direct shear device with a vertical load of 10 lb.

Maximum shear stress obtained at failure was 2.5 psi. The size of the shear box

was 2” x 2” and thickness of the specimen was 1”. What is the value of tan ’ ?

a) 4

b) 2

c) 1

d) None of the above

20. A soil specimen of 2” diameter was sheared in an unconfined compression device.Peak load at failure was measured as 31.4 lb. What is the value of the

unconfined compression strength?

a) 5 psi

b) 10 psic) 15.7 psi

d) 15.7 kN/m2





21. An unconfined compression test gives _______________________.

a) drained shear strength

b) c’ and ’

c) undrained shear strengthd) (a) and (b)

22. What are the devices that we use in the unconfined compression test?

a) load frame to compress the specimen

b) triaxial cell

c) rubber membrane

d) all of the above

23. You are analyzing the stability of a dry slope made of sandy soil having drainedfriction angle of 450. Total of Wcos is 400 lb, and total of Wsin is 200 lb.

Total of the length of the slice is 50 ft. What is the value of the factor ofsafety of this slope, using method of slice?

a) 1

b) 2

c) 0.5

d) 1.5

24. You need to work as a geotechnical engineer to design slope stabilizing measures

(to improve the safety factor) for a landslide that has occurred recently. Whatmethod do you apply?

a. Reduce the load at the toe of the landslide

b. Drain the water outc. Increase the load at the head of the landslide

d. All of the above

25. You are conducting two UU triaxial tests for the identical specimens at the

confining stresses of 10 psi, and 30 psi. The deviator stress at failure for the

confining stress (3) of 10 psi was 20 psi. What should be the diameter ofMohr’s Circle for the confining stress of 30 psi?

a) 20 psib) 60 psi

c) 40 psid) 30 psi





26. How do you measure the change in volume of specimen in a UU triaxial test?

a) by measuring the change in length of the specimen

b) by directly measuring the change in volume of water at the

burette.

c) by calculating the area of the specimen through the diameter ofthe specimen, multiplying it with the height of the specimen to

get the final volume and subtracting the final volume with theoriginal volume.

d) There is no volume change in a UU triaxial test.

27. In general, direct shear test is conducted to measure the,

a) drained shear strength

b)

undrained shear strengthc) unconfined shear strength

d) both (a) and (b)

28. Consolidation test is more important in case of,

a) clayey soil

b) sandy soil

c) filter materiald) none of the above

29. In a UU triaxial test, soil specimen is sealed in a rubber membrane and cellpressure is applied from outside in a radial direction. What is the objective of

sealing the specimen with rubber membrane?

a) To conduct the test in undrained conditionb) To maintain the difference between the cell pressure and pore

pressure so that the specimen can be confine at a certain effective

confining stress.

c) To make the sample more flexible

d) To maintain the same diameter of the specimen while shearing

30. The mass of a wet soil specimen in a tin was 240 g, the mass of the dry soil and

tin was 220 g. The mass of the tin was 20 g. What should be the nearest water

content?a) 9%

b) 10%c) 91%

d) 8%





31. After a consolidation test, the water content of a soil specimen having specific

gravity of 2.7 was 20%. What should be the nearest void ratio?

a) 0.27

b) 0.43

c) 0.54d) 0.05

32. Which among the following is the nearest unit weight of water?

a) 9.8 lb/ft3

b) 9.8 kN/m3

c) 62.4 lb/ft3

d) (b) and (c)

33. Moist unit weight of a soil specimen after a Proctor compaction test was 20

kN/m

3

. Water content of the specimen was 25%. What should be the dry unitweight of that specimen?

a) 18 kN/m3 b) 16 kN/m3

c) 15 kN/m3

d) 24 kN/m3

34. The soil specimen retained in the pan of a standard sieve analysis test consists

of ____________________________.a) Sand

b) Silt

c) Clayd) (b) and (c)

35. D10 of a soil mass means ______________________________.

a) Diameter of the soil is 10 mm.b) 10% of the soil mass is finer than this size.

c) 10% of the soil mass is coarser than this size.

d) Average size of the particle.

36. Which among the following is the average size of the soil particle?

a) D10 b) D30

c) D50

d) D60

37. Liquid limit of a soil specimen is 83%. Plastic limit of that soil specimen is 43%.The soil specimen currently has 53% water content. Which among the following

is the current state of that soil?





a) Liquid

b) Plastic

c) Semi-solid

d) Solid

38. Liquid limit of a soil specimen can be obtained from __________________.a) Rolling Method

b) Casagrande’s cup c) Hydrometer analysis

d) Sieve analysis.

39. While measuring the liquid limit, groove in the Casagrande’s cup method mustclose over a distance of approximately ______________________.

a) 12.5 mm

b) 10 mm

c)

25 mmd) 3 mm

40. Which among the following is the most general soil classification system?a) USCS

b) AASHTO

c) SW-CL

d) SW

41. On a graph of plasticity index versus liquid limit, what among the following is

true about the “A line”?

a) Soil above the A line is clay.

b) Soil above the A line is silt.c) Soil above the A line has high plasticity.

d) Soil above the A line has low plasticity.

42. A gravelly soil specimen has 6% clay and 2% silt. Uniformity coefficient is 5 andcoefficient of curvature is 0.8. What should be the USCS classification for that

soil?

a) GW-GC

b) GP-GC

c) GW-GM

d) GP

43. A Proctor compaction test is done to determine __________________.

a) Minimum dry density.b) Maximum dry density.

c) Optimum moisture content.d) (a) and (c)

e) (b) and (c)





44. On a graph of maximum dry density versus water content for a Proctor

compaction test, which among the following is true?

a) Sand specimen always gives a bell shaped curved.

b) Optimum moisture content is the water content when the curve

intersects zero air void line.

c) Maximum dry density occurs at the peak of the curve.d) Zero air void line can be plotted without the Proctor compaction test

if the specific gravity of the soil is known.e) (c) and (d)

45. What among the following is true about the degree of saturation at maximum

dry density of soil in the Proctor compaction test?

a) S = 100%

b) S < 100%

c) S > 100%

d) S = 0%

46. What should be the value of degree of saturation at zero air void curve of

Proctor compaction test?a) 100%

b) < 100%

c) > 100%

d) 0 %

47. Pre-consolidation pressure of a soil mass can be determined by plotting a ___________.

a) Deformation – log time graph.

b) Deformation – time graph.

c) Void ratio (e) – log ’ graph.

d) (a) and (b)

48. A soil specimen needs 3 hours for 100% consolidation in a consolidometer having

both side drainage. How long does it take for 100% consolidation if it is drained

from one side only?

a) 3 hours

b) 45 minutes

c) 12 hours

d) 9 hours.

49. A dam was compacted at the void ratio of 0.7 with a uniform sand of specific

gravity of 2.7. The nearest critical hydraulic gradient for the dam is ______.

a) 1.5b) 0.5

c) 1.0

d) 2.0





50. A square grid flow net for the seepage under a cofferdam shows 4 numbers of

flow lines and 12 numbers of equipotential lines. Difference between the

headwater and tail water was 10 m. Hydraulic conductivity of the material below

the cofferdam was 3 x 10-2 cm/s. The nearest seepage discharge per kilometer

length of dam should be ______________.a) 1 cm3/s

b) 1 m3/sc) 10-3 m3/s

d) 10-3 cm3/s

51. Strength of which among the following soils is most appropriately measured by

the unconfined compression testing device?

a) sandy soil

b) Over consolidated clay

c)

Gravelly soild) All of the above

52. An unconfined compression test is a ________________________.

a) special type of unconsolidated undrained test.

b) type of an undrained test.

c) type of u = 0 test.

d) All of the above

e) (a) and (b)

53. The deviator stress of failure for an unconfined compression test is 20 psi. The

nearest undrained shear strength is __________________________.a) 20 psi

b) 40 psic) 10 psi

d) 20 lb

54. An over consolidated clay having effective friction angle of 100 was sheared in

an unconfined compression device. What should be the nearest angle of

inclination of the failure plane in the specimen?

a) 350

b) 400

c) 450

d) 500

e) 550

55. A normally consolidated clay is sheared in a direct shear device of 4” x 4” size.The normal load was 320 lb. The peak shear resistance was 80 lb. What should

be the nearest value of cohesion?





a) 4 psi

b) 5 psi

c) 0 psi

d) 4 kPa

56. Which among the following parameters are measured with a direct shear device?a) c’ and ’

b) c and c) , and u

d) (a) and (c)

57. A normally consolidated soil specimen has shown the following measurements

while sheared in a shear testing device.

= 50 psi u = 10 psi = 20 psi

The nearest value of tan is __________________.

a) 0.25

b) 0.5c) 2

d) 0.4

58. What is the major difference between the Bishop’s Simplified Method (BSM)and the Method of Slice (MS) for slope stability analysis?

a) BSM always gives higher safety factor value than the MS.b) BSM is an iterative method.

c) BSM considers the difference between the vertical inter-slice

forces into account.d) All of the above

e) (a) and (b)

59. A stability analysis was done for a sandy slope using the method of slice, and thefollowing information was obtained.

W cos – U = 1000 kN = 450

L = 200 m W Sin = 500 kN

What is the closest value of the factor of safety?

a) 1

b) 2c) 2.4

d) 1.2

60. A soil specimen is sheared in an unconfined compression test device and peak

deviator stress was determined to be 20 psi. What is the expected value of theundrained shear strength of that soil if the specimen is sheared at the same

condition in an UU triaxial device at the cell pressure of 30 psi?





a) 50 psi

b) 10 psi

c) 20 psi

d) 5 psi

61. Volume of a soil specimen is 12 in3. This specimen is sheared in a UU triaxialtesting device. Change in length of the specimen is 1 in. If the initial area of the

specimen is 3 in2, what should be the nearest final volume of the specimen?a) 9 in3

b) 15 in3

c) 3 in3

d) 12 in3

62. An UU triaxial compression test was conducted to measure the shear strength

of soil for _____________________.

a)

slow and static loadingb) earthquake loading

c) soil layer sandwiched between two impermeable layersd) all of the above

e) (b) and (c)

63. How do we measure the volume change in the UU triaxial test?

a) By sealing the specimen in a rubber membrane and connecting the

ends of the specimen to the volume measuring device/burette withthe pipe.

b) By measuring the change in height of the specimen.

c) Volume change is not measured in UU triaxial test. Pore waterpressure is measured instead of it.

d) There is no need to measure the volume change, nor the pore waterpressure in the UU triaxial test.

64. Hydrometer analysis is done for soil classification in the following situation.

a) When soil is to be classified according to the USCS system

b) When soil is to be classified according to the AASHTO system

c) When % of clay is required

d) All of the above

e) a) and b)

65. Which among the following devices are used for specific gravity measurement?

a) Pycnometerb) Water bath

c) Thermometerd) a) and c)





66. A constant head permeability test is done for…….

a) fine grained soil

b) coarse grained soil

c) both a) and b)

d) consolidation test

67. To measure hydraulic conductivity of a clay soil specimen, which among the

following tests do you perform?a) constant head permeability test

b) falling head permeability test

c) rubber balloon test

d) seepage analysis

68. For the same head difference, discharge of water from single walled cofferdam

is always.

a)

Half of that in the double walled cofferdamb) Between 1 – 2.0 times that in the double walled cofferdam.

c) Same as in the double walled cofferdamd) Double of that in the double walled cofferdam.

69. An equi-potential line is a line that has.

a) same hydraulic gradient

b) same discharge

c) same water contentd) none of the above




Solution to Exercise Problems

QuestionNo. Answer

QuestionNo. Answer Question No. Answer

1 c 26 d 51 b

2 a 27 a 52 d

3 e 28 a 53 c

4 d 29 b 54 d

5 a 30 b 55 c

6 b 31 c 56 a

7 b 32 d 57 b

8 a 33 b 58 e

9 d 34 d 59 b

10 a 35 b 60 b

11 a 36 c 61 d

12 c 37 b 62 e

13 c 38 b 63 d

14 e 39 a 64 c

15 a 40 a 65 d

16 c 41 a 66 b

17 a 42 b 67 b

18 a 43 e 68 b

19 c 44 e 69 d

20 b 45 b21 c 46 a

22 a 47 c