Department of Civil Engineering
FACULTY OF ENGINEERING
GEOTECHNICAL ENGINEERING
(GET260S)
LABORATORY MANUAL
CLASS
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GROUP
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SURNAME
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NAME
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STUDENT NUMBER
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LECTURER
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TECHNICIAN
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Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
TABLE OF CONTENTS
STUDENTS MUST READ THE CONTENTS OF
THIS MANUAL VERY CAREFULLY
INTRODUCTION ..................................................................................................................... 3
EVALUATION CRITERIA GUIDELINES ............................................................................. 3
LABORATORY PRACTICAL SYLLABUS ........................................................................... 5
GUIDELINES FOR LABORATORY REPORT REQUIREMENTS ...................................... 6
LABORATORY SAFETY ...................................................................................................... 14
MYCLASSROOM AND ON LINE LEARNING .................................................................. 15
GENERAL LABORATORY GUIDELINES ......................................................................... 17
REPORT SUBMISSIONS ...................................................................................................... 20
SHORT LOAN BOOKS ......................................................................................................... 22
BASIC CHECKLIST FOR GEOTECHNICAL LAB REPORTS .......................................... 24
TEST 1:TRIAXIAL COMPRESSION TEST ......................................................................... 26
TEST 2: SHEAR BOX TEST ................................................................................................. 30
TEST 3: UNCONFINED COMPRESSIVE STRENGTH ...................................................... 36
TEST 4: OEDOMETER SETTLEMENT ............................................................................... 39
Test 5: FALLING HEAD ........................................................................................................ 47
TEST 6: CONSTANT HEAD ................................................................................................. 52
This material has been copied under license and is not for resale
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
INTRODUCTION
All soils need classification before being used for engineering purposes. Once the soil is classified and the
compositions of the grain particles are determined, one can make a recommendation as to which type of foundation
or pile structure should be used. There are various types of clay and not all of them may be regarded as bad. Some
are soft but are still stable. Collapsible soils are usually not very dense because of the high proportion of voids
present.
Heaving or active clays contain minerals, which cause the soil mass to react strongly to changes regarding moisture
content. These clays will swell when more moisture is added and will shrink as it dries out. The treatment of soft
soils is usually to make the foundations wider to reduce the pressure to an acceptable level so that the soil will be
able to withstand the load with little or no settlement. Should the soil prove to be too soft or wet then a raft
foundation or piling is recommended. A pile is a concrete column driven into the earth, which either carries the
load down to a stronger soil or rock below or, by hanging in friction on the soil around its shank.
In this semester S4, students will mostly work will cohesive clayey soils, although some non-cohesive sands will
also tested. Clay is generally smooth and has no visible particles; it retains water and does not drain well. The
presence of clay is sometimes indicated by cracks on the surface of the ground. This type of soil could pose a
problem although some soft clay is quite stable. Heaving clay is very problematic and changes a lot when the
moisture content changes. Sands can also present their own set of problems. This type of soil feels gritty and has no
plasticity and has good drainage properties. Generally, sandy soil is not a problem but on a steeply sloping site, the
weathered soil from the hill gradually slides down to the bottom and one might have collapsing soil problems.
Although laboratory testing is considered as a vital part of the decision process in ground engineering, practical
experience is also important. Past experience with problematic soils (local knowledge) is crucial. For example,
putting up a new structure adjacent to a building with serious settlement cracks is obviously a warning to the new
developer to investigate further!
EVALUATION CRITERIA GUIDELINES
Students are to regard this part of Geotechnical Engineering, GET300S, as an examination of laboratory practice
and skills, ie, thorough and thoughtful preparation must accompany each individual student attempting to complete
the practical syllabus. Students are evaluated according to their performance while completing the test AND
based on the reports handed in on time after each test completion. A pass mark of not less than 40% is
necessary to successfully complete the laboratory practical. The following “Test Case” examples should be
understood clearly as far as evaluation is concerned.
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
Test 1
Test 2
Test 3
Test 4
Test 5
Test 6
Average
Result
Student A
55
50
30
50
45
45
46
R
Student B
40
65
45
0
30
55
39
FAIL
Student A
65
60
0
75
55
80
56
R
Student C
70
75
90
0
0
55
48
FAIL
R = Failure pending re-evaluation of Test 3. A maximum of 50 % can be achieved for this re-evaluation. This
will take place only if a student achieves a minimum of 40 % as an average but performs weakly in only ONE
of the tests. A re-evaluation may take place as an online quiz or an oral test in the laboratory.
F = Outright failure of the laboratory practical. The student has under-performed in more than 2 tests
(achieving less than 40% in each case) and cannot be re-evaluated.
The mark allocation for the combination of laboratory tests and “online” submissions will be as follows:
Report = (75%)
-
Cover Page
-
2.5%
-
Content Page
-
2.5%
-
Flow chart for practical (NB: The Signed flow chart by the lab technician)
-
Introduction
-
Equipment
-
Method
-
10%
-
Results and graphs
-
30%
-
Analysis
-
15%
-
Comments and Recommendation if any and Conclusion.
-
-
2.5%
2.5%
Poster = (25%)
-
Layout
-
5%
-
Photos
-
5%
-
Results
-
5%
-
Graphs
-
10%
*NB: Report on what have been done in the laboratory.
Use the forms supplied, failing which, the marks will be lost.
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
-
5%
5%
HANDING IN OF PRACTICAL REPORTS
Completed lab practical must be handed in on the dates specified on the handouts. These practical must be in no
later than the time specified. No late hand-ins will be marked. No extensions for handing in or the reports.
LABORATORY PRACTICAL SYLLABUS
Each group will be given the opportunity to compete a series of tests on a soil type that is commonly found in the
Western Cape. In the S3 semester, soil and gravels tested in the laboratory were specific to road construction. In
the S4 semester the soils that will be tested are generally known as expansive cohesive soils (clays that can be
problematic when encountered under heavy structures). Yet other soils such as sands and cohesive gravels are
commonly found here in the Western Cape and some tests will be completed on these as well. The geotechnical
engineer or technician must assess these soils for what they are worth in forming part of the sub-structure. Only a
complete series of laboratory tests can determine whether the soils are useful of should be removed entirely below
the structure. So the emphasis will fall upon basic ground engineering and determining how soils behave when
placed under extreme load conditions. In this way, the soils will yield its unique properties so that an informed
decision can be made to its use in general engineering works.
 Many web sites offer assistance to students hoping to discover more about ground engineering. One can be
found at:
http://fbe.uwe.ac.uk/public/geocal/SoilMech/basic/soilbasi.htm or,
http://fbe.uwe.ac.uk/public/geocal/SoilMech/classification/default.htm
Go visit this web site and see what information can be extracted on the behaviour of soils.
Some soils will be prepared for the groups prior to the commencement of the laboratory testing procedures. Some
soils will be required to be sourced by the groups themselves. This will be discussed during the demonstration
sessions. Students who are already part of contractual work in the field are welcome to bring in problematic soils
for testing.
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
1.
GENERAL
Aims of the Laboratory Sessions
Laboratory sessions in the Department of Civil Engineering have three main aims:

To reinforce or complement the theory covered in lectures through practical examples.

To familiarize students with laboratory and testing procedures

To enhance the generic skills of students including the planning and carrying out of experiments, technical
writing and critical appraisal of data.
Students will discover the importance of aim 3 as they progress through their professional careers, whether or not it is
related to engineering.
On entering the laboratory, ensure that the following is done:
1. Have a flow chart (Marked and signed by the lab technician) before commencement. It is your
responsibility to ensure that the flow chart it signed.
The flow chart must include:
The title of the test to be performed
The aim/purpose of the test
The apparatus to be used
The procedure of the test
*The purpose of the flow chart is to ensure that the test to be carried out is known, why that test is being
performed, how it is done, and the apparatus to be used are identified. The flow chart is used as a
reference for tests procedures. Failing which you would not be allowed to do your practical, and thus you
will get zero for that practical.
2. Place your bags on the floor, not on the workbenches
3. Sign the register, which will be available for the first 10 minutes, and will be removed afterwards.
4. After completing the experiment, clean the work station, apparatus and store away.
The above must be strictly adhered to. If you fail to sign the register you won’t get a mark for the laboratory
session. You will be held responsible for any apparatus not stored, cleaned or returned and the reminder of the
group will lose up to 50%. You will find the laboratory clean and neat. Help to keep it tidy, by cleaning and
returning everything to the cupboard where you have found it.
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
Attendance to the practical laboratory sessions is compulsory. Student who do not attend, or have made some
alternative arrangements, will not be allowed to hand in any reports. In you being 10 minutes late, you will not be
allowed in the laboratory.
If the students want to do their lab sessions earlier or later, the class representative must arrange with the technician
in charge at least 24 hours before the practical time. This will only apply if it fit within the laboratory staff’s
schedule. Failure to prior arrangements will not get any marks for that specific practical.
2.
THE REPORT FORMAT
1. Cover page must include the name of the university, campus, department, subject, report title, your name
and student number, group (S1, S3 or S4, full time or part time), lecturer for that subject, and due date.
2. Content page must have the subtitles/headings and page numbers
3. Flow chart as mentioned under General.
4. The body of the report as mentioned under handing of practical reports. . Use heading 1 for the headings,
and normal for the text. The font must be Times New Roman and font size must be 12. The paragraphs
must be in 1.5 line spacing. The pages must be numbered.
LABORATORY RULES
1. You are reminded that the rules of the \university also apply in the laboratory.
2. Smoking, eating and drinking are not allowed in the Laboratory
3. Know the location of the first aid supply in you Laboratory
4. Report all accidents immediately. All injuries, however trivial, must be attended to as soon as possible.
5. When working with inflammable material, have a fire extinguisher at hand.
6. Acquaint yourself with the purpose, function and dangers present BEFORE working with a piece of
equipment.
7. Do not switch on or operate equipment without authority of lecture or technician. Wear safety clothing
where necessary.
8. You should work neatly, quietly and quickly. Soil is dirty. Students must thoroughly clean all laboratory
equipment after completing an experiment and return all equipment pieces to the appropriate cabinets. A
penalty in the report grade of 25% will be imposed if this is not done properly. The work place must also be
properly cleaned, and all soil must be discarded as instructed.
9. Use data sheets in the laboratory manual to record all data, not notebook or scrap paper. After the
completion of an experiment, neatly complete as much of the computation as possible and have the
instructor sign it before leaving.
Before approaching the instructor check that all information has been recorded on the data sheet (group
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
number, sample number, date. etc.). These sheets must be attached to the laboratory report.
10. Report all breakages and/or defective apparatus to the Technician or Lecturer in charge immediately,
otherwise you may be held responsible for their repair or replacement. If an accident is due to carelessness
the responsible party will be charged for the repair or replacement of the damaged apparatus.
11. Do not work on wet, greasy or oily floor. Grease and oil patches on the floor must be covered with sand
and sawdust.
12. Confine yourself to your laboratory concerned,
13. Do not work alone. It is good practice to have someone around to shut off the power, etc.
14. Remove all ring and other ornaments from your fingers, hand and neck before starting to work. Clothing
must not hang loose. Tie you hair.
15. Do not skylark in the lab. Never talk to anyone while working, as you cannot work.
16. Do not become overconfident and start to take risks.
17. Keep clear of other students. Avoid overcrowding.
18. No student is permitted to enter a storeroom.
19. No apparatus may be removed from the Laboratory.
20. After use, switch off all apparatus and leave benches in a neat order. Brooms and brushes are available to
clean laboratory.
21. Do not forget to return keys that have been issued. The university cannot be held responsible for damage or
loss of private property in the laboratory.
22. Each student is required to submit one laboratory report, worth 10% of the final course mark. The
laboratory sessions for which a report is required are marked on the group list on the laboratory
schedule. The reports are to be handed in to the Laboratory Technician (Asphalt Lab) within 1 week
of the laboratory session. Penalties will apply for late submission, and if any report is submitted more
than one week late no mark will be given.
23. You are expected to adhere to the University’s Academic Honesty policy. The laboratory report is expected
to be entirely your own work. The following are considered dishonest and will be penalized:

Copying some or all of another student's assignment without acknowledgement

Recycling reports from students from earlier years

Fabrication of data

Knowingly assisting another student in an act of academic dishonesty
24. FAILURE TO COMPLY WITH THE ABOVE RULES WILL RESULT IN DEDUCTION OF
MARKS!!
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
Geotechnical Engineering III Laboratory Project brief
The subject requires the student to complete several practicals. These practicals will be completed as part of a
project. A brief introduction to the practical will be given in class, followed by a demonstration (where required)
by the Lab Technician in the laboratory, and finally the student will take full responsibility for completing the
practicals under the supervision of the Lab Technician and Lab Assistant.
Brief
The Cape Peninsula University Of Technology is commissioning the Geotechnical Engineering III students to
investigate the feasibility of building roads and parking area located on the Bellville Campus site. The site is
suspect for poor compaction and the presence of clay may also be a possibility.
You are required to complete an individual report detailing your investigation. In order to facilitate the sampling
and the nature of some of the practicals you will perform, the class will split into groups of approximately four
students each. The students in the group will appoint a coordinator.
Each group will perform at least the following:
*
Sample the required material on site for the relevant laboratory tests;
*
Perform the following tests in the laboratory:
Direct Shearbox test, Triaxial test & Oedometer / Consolidation test
*
Produce a FLIPFILE (with typed report of EACH PRACTICAL emailed to the technician,
minniesl@cput.ac.za) to the Lab Technician. (Each student shall hand in an individual report) in the
Assignment cabinet in front of the Concrete Laboratory.
*
A2 size POSTER emailed to the technician, minniesl@cput.ac.za
Each report shall include the following:

Cover Page(Name & Surname, Stud. nr., Subject Name, Practical heading, Group Name & Name of
Lab Technician)

Objectives of the report;

Location of the site;

Soil profile;

Description of each test and results (do not retype the TMH1). Summarise the descriptions noting the
key aspects of the test in not more than 20-25 lines where possible.)

Flow Chart

Calculations & Graphs
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014

Analyzing, Interpretation and discussion of the results;

Conclusions and recommendations.
Laboratory
Students are required to book time in the laboratory in order to complete the project. A FLOW
CHART(neatly hand written/typed) must be submitted to the Lab. Technician and signed by the Lab. Technician
before the start of any practical. The Lab. Technician will also track and monitor the progress of the various
groups. Students must follow the laboratory rules or may be ejected from the laboratory. Booking of the
laboratory is essential. It is the responsibility of the group to manage their project;
Hand-ins
1.
A completed typed report to be handed in the following week, before the start of the next practical.
Evaluation
The project is 20% of the course mark. The project mark will consist of the following marks:
1.
Lab Technician’s mark of the individual test hand-ins.
2.
Group members evaluation of the contributions of each member. An active group member participating in
all agreed activities will be assigned 100%.
3.
modification of the project mark by an external moderator.
Lab Technician: L. Minnies
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
Laboratory Practical Schedule
Flow Report
Week
Chart hand-in
3
No
No
4-6
Yes
Yes
Practical
-
-
Introduction & orientation
Direct Shearbox test (undrained)
Reference
Lab. Technician
ASTM - D 3080-72
Objectives
To demonstrate safety issues in the laboratory
To familiarize the student with a procedure for rapidly
determining the strength parameters internal friction
angle and cohesion for a soil.
To introduce the student to the basic procedure for
7-8
Yes
Yes
-
Triaxial test (undrained)
AASHTO - T296-95
determining the soil parameters internal friction angle
and cohesion of a soil.
9-10
13
Yes
Yes
No
No
Oedometer test / Consolidation
test
Unconfined Compression Strength
(UCS)
No
No
Permeability (Constant Head & Falling
Head)
Yes
Yes
Laboratory Flipfile: (Hard copies &
Electronic files)
Poster: Electronic file
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
ASTM -
To introduce the student to the procedure of conducting
D2435 consolidation test and reduction of
collected data
SANS 3001-Part
GR53:2010
ASTM - D2434
Falling Head Not
Standardised - KH
Head,Volume
2,Chapter 10
Lab. Technician
To introduce the student to an approximate procedure for
evaluating the shear strength of a cohesive soil.
To introduce the student to two methods of determining
the coefficient of permeability
To equip the students with a laboratory profile to
showcase their work to industry.
Page 11
Civil Engineering Program Outcomes
The Program Outcomes listed below are expected of all students of the Civil
Engineering laboratory program. Below are program outcomes expected to be
achieved in this course.
a)
an ability to apply knowledge of mathematics, science and engineering; Geotechnical
Engineering
b)
an ability to design and conduct experiments, as well as to analyze and interpret data; students
will conduct experiments, analyze and interpret data
c)
an ability to design a system, component, or process to meet des ired needs;
d)
an ability to function in multidisciplinary teams;
e)
an ability to identify, formulate and solve engineering problems;
f)
an understanding of professional and ethical responsibility;
g)
an ability to communicate effectively; students will work in teams
h)
the broad education necessary to understand the impact of engineering solutions in a global and
societal context;
i)
a recognition of the need for and an ability to engage in life-long learning;
j)
a knowledge of contemporary issues;
k)
An ability to use the techniques, skills and modern engineering tools necessary for engineering
practice; students will use various laboratory equipment including state-of-the-art data acquisition
system; students will analyze data using Excel;
l)
proficiency in mathematics through differential equations; probability and statistics; calculusbased physics and chemistry;
m)
proficiency in a minimum of four (4) recognized major civil engineering areas;
n)
an ability to conduct laboratory experiments and to critically analyze and interpret data in more
than one of the recognized major civil engineering areas; in addition to conducting experiments in
soil mechanics, students will learn how the obtained results can influence design and construction
decisions in other civil engineering areas;
o)
an ability to perform civil engineering design by means of design experiences integrated
throughout the professional component of the curriculum;
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
Page 12
p)
an understanding of professional practice issues such as procurement of work; bidding versus
quality based selection processes; how the design professionals and the construction professions
interact to construct a project; the importance of professional licensure and continuing education;
and/or other professional practice issues.
Design Activity:
Following instructions in the textbook and appropriate standards, students are
required to design
one field experiment.
Engineering Standards:
Students will become familiar with TMH 1, ASTM, AASHTO and British standards
related to testing in Geotechnical Engineering.
Realistic Constraints:
Realistic constraints such as economic, manufacturability, ethical, health and safety
are discussed
at the appropriate times when experiments are being
discussed.
Computer Usage:
Computer usage is required for the report preparation and data analysis. Students
will also use
state-of-the-art data acquisition system.
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
Page 13
LABORATORY SAFETY
1. Please adhere to all the rules regarding safety as explained on the first day of arrival in
the laboratory.
2. No smoking or eating is allowed inside the laboratory premises.
3. Proper shoes are to be worn. No sandals, high heels, bare feet or any shoe type that is
not closed entirely on top.
4. Oven protection gloves must be worn when removing or placing items in the ovens.
5. Do not operate electrical equipment without consent or proper supervision.
6. The gas primer cylinders must be monitored at all times when operational.
7. Care must be taken when handling heavy equipment such as hammers and steel pipes.
Do NOT swing these items recklessly around your person.
8. Chemicals (sodium silicate) will be used in the A5, 6 tests. Be careful when
administering these chemicals during the test.
9. If water is accidentally spilled on to the floor, it MUST be wiped clean immediately.
10. Any unusual circumstances that could possibly lead to a hazardous situation must be
reported to the technician immediately.
11. Access doors at the back of the laboratory will remain open at all times.
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
Page 14
MYCLASSROOM AND ON LINE LEARNING
The E-learning facility at CPUT will allow students to log into a useful resource made
available for GET302S. The steps to follow are simple: From the Homepage of the CPUT
webpage, go to “E-learning”, then “New Campus eClassroom”.
Log in using the following:
username: student number
password: date of birth in YYMMDD format (or first six digits of ID)
1) Log on using your own student number and ID number (first 6 digits). Click on
Geotechnical Engineering 3 Practical and you will now have access to a host of extra
information.
2) Evaluation Tools/Quiz MUST be accessed and completed as part of the preparation of
the laboratory module. A mark will be allocated after submission of each of the 6
quizzes and will be used as part of the final mark. Submit these quizzes in the week
of the lab tests.
3) A chat box is available for information not found generally. Notices will also be
posted weekly during the test practical as far as reports are concerned. Do not abuse
this facility for personal messages. It will be switched off in this case.
4) Study Tools/Laboratory Apparatus will provide some information of the current and
latest apparatus available in industry.
5) Make sure that the course requirements for the laboratory module are understood.
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
Page 15
6) Do not hesitate to ask your technician/tutors for more information about this facility.
7) If you cannot see the subject you have registered for, speak to your laboratory
technician so that your access can be granted.
8) All students MUST use the facility on WebCT to choose a group to work in for
the rest of the semester. A maximum of 6 per group is allowed.
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
Page 16
GENERAL LABORATORY GUIDELINES
A.
When you arrive at the laboratory make sure that you know the following
1.
Precisely why the experiment (test) is being done, and what it entails.
2.
Which apparatus you are going to use, and how it works. Please do not fiddle
around with apparatus you do not understand (a demonstration of the testing
procedures would have been done before the lab session).
3.
Know your group members, - and know what each person is expected to do in
the laboratory during the test. The above-mentioned are necessary to ensure that
you complete the experiments within the time limit allocated.
B.
The following procedure is necessary to successfully complete the test in the
laboratory:
1.
When you enter the laboratory leave your personal belongings on the floor (not on
the work bench) close to the work area.
2.
Sign the register, which will be provided (sign within the first 10 minutes, after
which the register will be removed).
3.
With the aid of the map, determine your cupboard number, and take the
appropriate key from the holder (the cupboard though may be open for each
group).
4.
Inside the cupboard you will find a complete set of all the apparatus and the
specimens needed for testing. Some apparatus is installed complete upon the
worktable.
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
Page 17
5.
After you have checked the apparatus, follow your flowchart to complete the test.
6.
After you have completed the test, clean the apparatus and place it back in the
cupboard (where applicable).
7.
Recheck the apparatus to make sure that all the apparatus are in the cupboard, and
then lock the cupboard.
8.
Return the key to its original position.
The above-mentioned procedure must be strictly followed. Make sure that the correct
apparatus is in the cupboard (except any moisture content basins which have to be left
overnight in the oven) before you leave the laboratory. If any of the apparatus are
missing, you and your group will be held fully responsible, and the group will loose
marks (up to 50%).
You will find the laboratory in a clean and neat condition, please help to keep the
laboratory in this condition by cleaning the equipment and returning it to the
appropriate cupboard. Do not remove any soil samples from the laboratory.
It is compulsory to attend all laboratory practical sessions, and no student will be
allowed to hand in a laboratory report if he/ she did not attend the laboratory
class. Any alternative arrangements must be organised in advance with the
technician/lecturer if you cannot attend.
If students want to change the time of their laboratory sessions to an earlier or later
date, the group leader must discuss this with the lecturer and the laboratory technician
3 days before the intended change. These changes will only be possible if the
intended change will fit into the laboratory technician's programme. Students or
groups who do not arrange changes within the specific time, or who work in the
laboratory beyond the allocated time, will receive no marks for that specific
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
Page 18
laboratory test. Evaluation must take place at the specified times.
In the event of anyone causing any damage to apparatus that person will be held fully
responsible for the damage caused. Money that is due in order to fix or replace
damaged equipment will be collected. Report any damage immediately.
In cases where moisture content samples are left in the oven to dry overnight, it must
be weighed the next morning. Please do this before 11H00 on that specific day. The
laboratory staff will then clean the laboratory and ovens and any dry samples
remaining in tins or pans will be thrown away. Students who fail to weigh their
samples will receive no marks for that part of the test. Please arrange with the
laboratory technician if the sample cannot be weighed before 11 o'clock.
After weighing oven-dried samples as described in the above paragraph, empty the
containers in the special dirt bin provided (next to the glass office). The containers
must then be cleaned and placed in the correct cupboard where it was originally
found. Test samples must be left in the plastic bowl provided next to the apparatus
used.
All apparatus has been marked, so please don’t damage or remove the container or
apparatus markings.
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
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REPORT SUBMISSIONS
Each student is responsible for their own completed laboratory book which must be
handed in on the dates specified on the attached timetables. These laboratory books
must be deposited in the glass office door in Rm 3.74 before 09H00 on the specific
handing-in date. Each group will have received their handing-in dates (see the list
attached in the front of this manual), and no excuses will be accepted (doctors’
certificates excluded), and late entries will not be marked. No extension of time
will be granted. Be warned! The technician or his tutors will not engage in any
discussion over the reasons why reports are late. To do this will only lead to
unfair discrimination toward the students who have their reports in on time.
Marked laboratory reports will be made available in Rm 0.17 within 7 working days
after initial handing in. A notice will be posted out on the network and students will
receive a time and date via the “Myclassroom” facility. Students are not to enquire
as to when the books will be marked! Each student is responsible for his/her own
report. ENSURE THAT A MARK IS ALLOCATED FOR THE INDIVIDUAL
TEST.
Do not copy another group member’s data or answers (except the test data which has
to be shared among each group member). Your report must be unique and contain
your own work. Sources may coincide with the rest of the group. Students who work
on loose pieces of paper and not on the standard forms provided will be penalised.
Make sure that you have studied and understood the forms that you are going to use
(ASK IF YOU NEED HELP!!)
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
Page 20
TEST WEEK
Two test weeks are arranged during the semester when various tests are written,
including GET302S. Laboratory reports that happen to fall during these test weeks
are regarded as part of the subject examination and may be requested to be handed
in. Prepare these reports well ahead of time so that no pressure is felt during the test
week. Consult the syllabus time roster or speak to your lecturer as to when this test
week will occur.
Quote: “If a student cannot adequately explain the reason for their poor report then
the examiner cannot be expected to explain the reason for the poor mark allocated”!
[Anonymous]
CS Lewis: “Education, without values, if anything else is useful, but the end results
in making man a more clever devil”. (So be careful how you prepare your reports
and be truthful in all things)
THE FLOWCHART
The flowcharts are a short, step-by-step procedure, of showing the different processes
involved in completing the test. This flowchart does not replace the “method” section
in the report. It is included as an aid for the student before the test commences and
prepares the student before the time regarding what to expect. The flowchart must be
presented in a neat and professional format, but be careful to not make it too long or
complicated.
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
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The flowchart is to be drawn up by each individual student in the group and
shown to the technician or lecturer in charge of the laboratory session. If the flowchart
is poorly written (ie, use of pencil; no arrows, poor logic) and is obvious that no
thought has been given to the task, then a poor mark will be entered for that part of
the test (a mark is given out of 10). NO FLOWCHART SHOWN WILL RESULT
IN A ZERO MARK AND PLEASE DO NOT WRITE IT OUT WHILE THE
TEST IS BEING DONE!
SHORT LOAN BOOKS
Useful reference books are made available to all students in the library section known
as “short loan”. These books may be used on the day but not may be allowed out of
the library. The following can be found that will assist in reading material when
researching the “Discussion” questions.
 KH Head, Vol 2. Manual of Soil laboratory Testing
 ASTM Standards Vol 04.08 Soil and rock Dimension
 Elements of Soil Mechanics, GN Smith 4th and 6th Edition
 Soil Mechanics. MJ Smith 4th Edition
Students are encouraged to do research on the many Internet web sites dedicated to
ground engineering for further study and information useful for the completion of the
individual laboratory reports.
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
Page 22
Example of a flowchart
Sampling of fine aggregate
1
Inspect st ockpile
for foreign mat erial
Yes?
Foreign
mat erial
evident ?
Remove foreign bulk
mat erial & remix
st ockpile
No
Randomly select
sample sit es
Ext ract enough t o
fill 2 pans
Arrange riffler pans
Split away 2
opposit e half's
int o 2 pans
Dig ±1 m below
surface. Ext ract
sample.
Empt y pans ont o
PVC t arpaulin
Riffler slot s = 13.2 mm
Remix & separat e in
half by coning
Combine bot h pans
t hrough riffler
Reduce t o± 10 kg samlped
At t ach Label
inside and
out . Mark
adequat ely
Dispatch to
test lab
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
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BASIC CHECKLIST FOR GEOTECHNICAL LAB REPORTS
1. Include Declaration Sheet on the first page! (See last page in this manual)
2. Aim of the test (why the test is needed- 3 to 4 lines)
3. Description of the aggregate or soil used in the test procedure: (include the source and
correct geological name- 5 to 5 lines)
4. Description of the test (a short summary of how the test is started and ended
according to the standard procedure followed- 5-6 lines). Provide which standards are
being followed, ie TMH1, COLTO, SABS1200, ASTM
5. Flowchart (one A4 page long in the correct block & arrow format)
6. Method statement (tell the examiner what YOU did in your own words on the day of
the test, from start to finish- not longer than one page)
7. Theory and calculations (explain the usefulness of the test and how it fits into the
greater scheme of geotechnical analysis; provide mathematical calculations where
applicable of how the results are computed, one page long)
8. Results and graphs (mark off clearly on the results what is significant and important in
the evaluation of the results)
9. Discussions. Answer all questions provided, in full detail. What is important is how
YOUR test result fits into the general specifications.
10. Conclusions. Provide a full analysis of the final outcome of the test results (can the
aggregate be used for any layer works, what recommendations would you make to
improve the soil, what would the aggregate not be suitable, etc).
11. References. Provide a list of exact references (or interviews) used in sourcing your
information. This must be believable references. Use the library short loan department
or the Reference section. If a book is used, provide the author’s name, Title of the
textbook, page nr’s used in the reference. If an Internet source has been used, provide
the reference accurately (date the webpage was visited, who the author is and the title
of the page, as follows: http\\: www.mysouces.org.za, 15 March 2006, JE Hoover,
“Analysis of Soils for Foundational Support”. Always give credit to the person who
wrote the article! Don’t plagiarize (copying existing work as if it was compiled as
your own!)
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
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12. If the above sections are thoroughly researched and in place, there would be no reason
why an overall mark of more than 60 % cannot be attained.
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TEST 1: TRIAXIAL COMPRESSION TEST
The triaxial compression test is used to measure the shear
strength of a soil under controlled drainage conditions. In the
conventional triaxial test, a cylindrical specimen of soil
encased in a rubber membrane is placed in a triaxial
compression chamber, subjected to a confining fluid pressure,
and then loaded axially to failure. Connections at the ends of
the specimen permit controlled drainage of pore water from
the specimen. The test is called “triaxial” because the three
principal stresses are assumed to be known and is controlled.
Prior to shear, the three principal stresses are equal to the
chamber fluid pressure. During shear, the major principal
stress, s1 is equal to the applied axial stress (P/A) plus the
chamber pressure, 3. The applied axial stress, 1 - 3 is termed the "principal stress difference" or
sometimes the "deviator stress". The intermediate principal stress, 2 and the minor principal
stress, 3 are identical in the test, and are equal to the confining or chamber pressure hereafter
referred to as 3.
IMPORTANT
1. Prepared clay samples will
Rubber membrane
Stretch apparatus
Apply suction
Pinch 0-ring against cap
ends
be available on the day of
the test, and will be next to
the apparatus that you are
going to use. Please handle
the samples with care so
38 mm specimen
that you do not disturb
them.
Perspex cap-ends
2. Determine the sample dimensions before the test is actually started.
3. Fit the two rubber O-rings* over the one side of the membrane stretcher and roll them
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
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to near the middle of the stretcher length (on one side of the breather pipe). See the
sketch below to follow the correct sequence.* Stretch the O-rings to warm them up
first.
4. Make sure that the valve on top of the air-water cylinder is tight before any water is
let out.
5. Make sure that the wing nuts on top of the cell body are well tightened, but please do
not force them (read the note attached to the apparatus).
6. Make sure that the triaxial cell is located centrally on the loading plate (check from
one side of the apparatus).
7. The gear change position should always be on “A” (strain rate 1,52 mm per minute)
20% per minute. A 'gear-knocking’ sound will be heard after the test has begun. This
is normal. If the sample is too wet, the load gauge above will not register immediately
alongside the penetration depth gauge.
8. The following range of cell pressures must be adhered to by the following groups:
GROUP NO
TEST 1
TEST 2
TEST 3
1,4,7
80 kN/m²
180 kN/m²
360 kN/m²
2,5,8
100 kN/m²
220 kN/m²
440 kN/m²
3,6,9,10
140 kN/m²
260 kN/m²
420 kN/m²
9. The compression test is continued until failure has occurred, ie 2-3 readings remain
constant or begin to fall back (decrease). This can also be translated to a 20 % strain,
which is equivalent to 15-16 mm compression. Beyond this point the specimen
becomes severely distorted and further readings become irrelevant. Use the load
reading as 20 % to do the rest of your calculations.
10. Clearly mark the failure load observed during the test.
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11. Make a clear sketch of each sample after failure has taken place.
12. Determine the moisture content of each sample after testing.
13. Remove the rubber membrane and O-rings carefully and wash the end caps, rings
and membrane (inside and out). Hang the membrane on the wooden stands provided
for drying out. Other groups will use the membrane.
14. There is no need for membrane corrections to be applied to the final result.
Discussion
15.1
What is the main purpose (objectives) of the triaxial test?
15.2
Where in the engineering field would you apply certain aspects of the triaxial test?
Explain how the application of the test is useful in your choice. (For example, the
angle of friction can be used in designing an anchor block for a pipe bend that
undergoes high velocity).
15.3
What are the advantages, and b. disadvantages of this test (based on your experience
doing the test)? See also KH Head Vol 2 in the library for further discussion.
15.4
State typical shear strength values that you would encounter in different clay types.
Tabulate a typical chart with values and include where exactly your test sample will
fit in.
15.5
Name and sketch the three main forms of specimen failure that may occur.
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
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15.6
Use the example soil set below to complete your graph, showing clearly how the
cohesion, angle of friction and maximum shear stress values are obtained. Use
formulae where necessary. A neat graph must be attached to your report.
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
Page 29
TRIAXIAL(Undrained)
TEST NO: ......................... GROUP NO: .........................
DATE:...................... ......
SAMPLE
MOISTURE CONTENT
FAILURE
DIAGRAM
Description:................
Tin No.............................
Length: ............................. mm
Mass Tin:.........................
Diameter .......................... mm
Mass Tin and Wet Mat ................. g
Area..................................mm2
Mass Tin and Dry Mat ..................g
Max. Stress .................... kNm2
Mass Dry Mat .............................. g
Strain Rate ............ % per min
Mass Water .................................. g
Cell Pressure .................. kNm2
Moisture Content .......................... %
g
Proving Ring Factor : 1Div. = ............................................ kN/div.
Strain Load LOAD Area
Gauge Gauge
N
mm2
mm
Div.
0.4
0.8
13
Strain Strain Load LOAD Area
Gauge Gauge
%
N
mm2
mm
Div.
8.4
8.8
1.2
1.6
2.0
2.4
2.8
3.2
3.6
4.0
4.4
4.8
9.2
9.6
10.0
10.4
10.8
11.2
11.6
12.0
12.4
12.8
5.2
5.6
6.0
6.4
6.8
7.2
7.6
8.0
13.2
13.6
14.0
14.4
14.8
15.2
15.6
16.0
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
1-
3
Strain
%
Page 30
TEST 2: SHEAR BOX TEST
In principle the shear box test
is an 'angle of friction' test, in
which one portion of soil is
made to slide along another by
the
action
of
a
steadily
increasing horizontal shearing
force, while a constant load is
applied normal to the plane of
relative
movement.
These
conditions are achieved by
placing the soil in a rigid metal
box, square in plan and consisting of two halves. The lower half of the box can slide
relative to the upper half when pushed by a motorized drive unit while a yoke
supporting a load hanger provides the normal pressure. During the shearing process,
the relative displacement of the two portions of the specimen and the applied shearing
force are both measured so that a “load vs displacement curve” can be drawn. There
are 2 types of shear box machines in the laboratory, type “A” and “B”.
IMPORTANT
1.
In all your calculations, use g = 9,81 m/s.
2.
Determine the sample dimensions before the test is actually started.
3.
Use the wooden dolly to push the sample into the Shear box. Be careful not to disturb
the sample. The grip plates must “bite” into the moist sample.
4.
Make sure that the perforated plates are perpendicular to the direction of the shear.
5.
Under no circumstances should the motorized reverse gear Type “A” be used.
Rather use the hand wheel to rewind the shear box after the test is completed.
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
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This is done after the clutch mechanism has been released.
6.
All the groups must use the lever arm ratio of 5 for type “A” (older motorised unit)
and 10 for type “B” (newer digital unit).
The motorised units have been set at 1.5 mm/min (motorised) and 5 mm/min (digital).
DO NOT TAMPER WITH THESE SETTINGS.
7.
NB - 20% will be deducted from each group who fails to remove the clamping
screws before the motor is switched on (marked red). Damage will occur to the
motorised gears if not removed.
8.a
The normal pressures applied to specimens in a set of tests should generally "bracket"
the maximum stress likely to occur on site. Normal pressures of about 50%, 100 %
and 150 % of this value are often appropriate.
All groups are to calculate the applicable test weights needed to apply the
stresses shown below (show this in your “Theory” section). The following
maximum stress (100%) conditions are applicable to the different groups. Set up
your moment formula in class before the laboratory session begins.
8.b
Type A
Type B
Group number
Normal stress
Normal stress
group 1,4,7,10
93.13 Kn/m²
77.2 Kn/m²
group 2,5,8,11
147.63 Kn/m²
131.7 Kn/m²
group 3,6,9,12
174.88 Kn/m²
186.2 Kn/m²
For example, if 100 % stress allows a mass of 10 kg to be applied, then 50 % and
150% would be 5 kg and 15 kg respectively. Begin with the lower % stress. Use a
moment formula to calculate the mass needed. Round this mass up to the nearest
whole number, as there are only a selected number of ring weights available. See the
sketches below to visualise the moment formula around each shear box type. See the
laboratory schedule for the type your group will use.
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
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Type AA@
motorised
Sample
Type AB@
digital
Ratio 5:1
Hanger
yoke
mass
Levelling
beam mass
Weights
and hanger
mass
Sample
Ratio10:1
Hanger
yoke
mass
ignored
Levelling
beam mass
ignored
Weights
and hanger
mass
Example for calculating the mass needed for a total stress (100%) = 169 kN/m² on a
60x60 mm shear box using a 5:1 beam ratio.
Hanger mass= 0.7 kg; beam & swivel mass=2.2 kg; yoke mass=3.1 kg
Using Moment Formula, solve for M:
[
(0.7 * 5 * 9.81)  (2.2 * 2.5 * 9.81)  (3.1* 9.81)  (M * 5 * 9.81)
]/1000  169
0.0036
Answer: 10.1 kg, so round down to 10 kg, so
Test 1 @ 50% = 0.5*10=5kg
Test 2 @ 100 % =1*10 =10kg
Test 3 @ 150% = 1.50*10 = 15kg
9.
Clearly mark the maximum shear stresses obtained during the different tests on
the data sheets provided, thus the shear stress at which the samples failed. Readings
are taken every 15 seconds for type “A” and 10 seconds for type “B”, after the
stopwatch has started. Start the stopwatch the moment the gauge registers
movement.
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
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3
1
kN/m
stress
Shear
2
M Angle of friction
C
Normal stress kN/m
Discussion
Typical stress failure of clay in a shearbox test
10.1
What is the main aim of the shear box test?
10.2
Where in the engineering field would you use the properties that you have described
in 10.1 above? Name six. Explain how the application of the test is useful in your
choice.
10.3
Tabulate the advantages and disadvantages of this test? Mention 3 of each.
10.4
What is friction, and which factors influence the angle of internal friction of a soil? (4
factors)
10.5
What is cohesion, and which factors influence the cohesion of a soil? (Name 4)
10.6
State typical values for angle of internal friction and cohesion of various soil types
and thereafter, determine the class of soil you tested.
10.7
Divide soils up into the various categories that classify them according to their
strength properties.
10.8
Determine the soil’s saturated density of the sample inside the cutter ring. Convert the
answer to dry density. Assume a sample height of 19 mm.
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
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SHEARBOX(Undrained)
TEST NO: ......................... GROUP NO: .........................
DATE:.........................
SAMPLE DIMENSIONS
Length:................................mm
Height:................................mm
Breadth: ............................. mm
Soil description : ..................................
Area ............................................. mm2
APPARATUS
Proving Ring Factor: 1 Div. = ....................N/div.
Lever Arm Ratio:....................................
Vertical Load: ........................................kg
Normal Stress ........................................ kN/m2
Mass of Yoke and Hanger....................kg
Mass of Beam ...................................... kg
Mass of Beam and Hanger .................. kg
TIME
min - sec
GAUGE READING
Div.
SHEAR FORCE SHEAR STRESS
kN
kN/m2
VERTICAL
mm
0-15
0-30
0-45
1-00
1-15
1-30
1-45
2-00
2-15
2-30
2-45
3-00
3-15
3-30
3-45
4-00
4-15
4-30
4-45
5-00
5-15
5-30
5-45
6-00
6-15
6-30
6-45
7-00
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
Page 35
TEST 3: UNCONFINED COMPRESSIVE STRENGTH
This test method covers the determination of the
Unconfined Shear Compressive Strength of a
cylindrical specimen of cohesive soil on a site. In
this test the sample is placed between two plates
without any lateral support. A vertical load is
applied by hand through a spring, the strain of
which is measured by an autographic recording
arm on a chart. In this test the sample is sheared
rapidly and no draining takes place.
IMPORTANT
1.
Prepared clay samples will be available on the day of the test, and will be in an
airtight container next to the apparatus. Please handle the samples with care so that
you do not disturb it.
2.
Check if the sample dimensions are the same as the standard dimensions that is
generally accepted. The samples are all marked, from 1 to 3. Use no.1 for the lowest
spring strain and no.2 for the next highest, and so on up to no.3.
3.
Use the three different springs to ensure that you get a good result. Do not forget to
write down each spring stiffness factor. Fix the graph chart onto the face frame of the
apparatus. A transparent mask is used to read off the “peak strain” factor.
4.
Compress the specimen by rotating the handle steadily at a rate of one turn every 2
seconds (practice before you start the test). A diagram below shows a typical stress
curve.
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
Page 36
DEFLECTION in mm
0
0.02
0.04
0.06
Spring
factor
0.08
0.1
Typical example of failure on a UCS graph
5.
During the test, keep you ringer on the base of the L-shaped arm to ensure that
there is good contact between the L-shaped arm and the adjustable stop. Make
sure that the pencil tip is at the origin (the top corner of the graph) before
starting.
6.
Each test is completed when the specimen has failed and a definite peak on the graph
plot is shown, or when a strain of 20% (16 mm deflection) is reached (which ever
occurs first).
7.
Before removing the sample from the machine plate, make a clear sketch in the space
provided on the data sheet.
8.
A moisture content determination must be done on each sample tested.
Discussion
9.1
What is the aim (objectives) of the Unconfined Compressive Strength test?
9.2
Where in Civil engineering would you use the properties that you have described in
9.1 above? Explain how the application of the test is useful in your choice
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
Page 37
9.3
What are the major advantages of this test ? Name 4.
9.4
When compared with the triaxial test, what are the disadvantages of the UCS test?
Name 3.
9.5
State typical shear strength values that you would find in different types of clays.
9.6
Name and neatly sketch the three main types of failure that may occur.
9.7
What is meant by 'clay sensitivity'? Discuss briefly and give parameters to distinguish
between the various types of clay.
9.8
Classify your clay sample according to any general classification system based on
typical UCS results. Name your reference source.
9.9
Use the average UCS value from your test result and design a pad foundation suitable
for carrying a concrete pillar of 4 m in length and 300 mm in diameter, carrying a dead
axial load of 400 kN. Use a safety factor of 3. Take the density of cured concrete to be
2450 Kg/m 3
Test Calculation Example
Spring factor used = 8 n/mm
Spring calibration factor =0.045
Deflection read off graph = 7.5 mm
Unconfined compressive strength=8*0.045*1000 = 360 kPa
Shear strength = 0.5*UCS = 360*0.5 = 180 kPa
Cohesion = "0.25*UCS = 360*0.25 = 90 kPa (this figure is a rough estimate and is not entirely
accurate)
% strain = 7.5mm / 76mm*100 = 9.9 %
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
Page 38
Unconfined Compression Strength(UCS)
TEST NO: ......................... GROUP NO: .........................
DATE:.........................
Date:
Spring Rate:
Site:
Specimen Weight:
Sample No.:
Wet Density:
kg/m3
Soil Type:
Dry Density:
kg/m3
Max. Compressive Strength:
N/mm
g
N/mm2
Moisture Content: Tin No.:
Moisture Content:
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
%
Page 39
TEST 4: OEDOMETER SETTLEMENT
This test is carried out by applying a sequence
of three to four vertical loads to a laterally
confined specimen with a height of about onequarter of its diameter. The consolidation cell
consists essentially of a metal mould for
containing and rigidly supporting the test
specimen. During the compression process,
measurements of the sample's height are made
over a period of time, usually up to 24 hours.
Since no lateral deformation is allowed, it is a
one-dimensional test, from which the onedimensional
consolidation
parameters
are
derived. In this semester, some groups will
perform a falling head permeability test as well and will run concurrent with the
oedometer test. The technician on duty must be approached for assistance in the
setting up of this section of the test.
IMPORTANT
1. The Oedometer test will take one week (5 days) to complete, so the following test
sequence must be strictly followed:

MONDAY: Preparation of Oedometer cell and sample (%MC, etc.) Setting up of
apparatus

Initial loading

Record results (settlement) for at least an hour. Leave data sheet in lab above test
apparatus
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
TUESDAY: Record settlement (24 hours). Additional loading

WEDNESDAY: Record settlement (48 hours). Additional loading. Prepare
apparatus for the Falling Head Permeameter test. [See the attached sketch in Fig
10.41]. Additional apparatus required are:
1. Graduated burette with manometer stand.
2. Silicon tubing
3. De-aired water
4. Stop watch

THURSDAY: Record settlement (72 hours). Complete Falling Head Permeability
Test. Remove loading.

FRIDAY: Record rebound (final settlement height)

Take out the sample of the cutting ring and determine the
final moisture content.
2.
In all your calculations, use g = 9,81 m/s.
3.
Prepared clay samples in the cutting ring will be
available on the day of the test, and will be next to the
apparatus that you are going to use.
4.
2005. Curtesy Matest
Catalogue
Use the large spatula to cut the excess clay from the sample, so that the sample is
level with the cutting ring. Use this excess clay to determine the initial moisture
content.
5.
Determine the height of the sample before you start the test, and the diameter after
you have taken the sample out of the cutting ring to determine the final moisture
content.
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
Page 41
6.
Make sure that the porous disc is completely saturated before you assemble the
Oedometer cell.
7.
Check and adjust the counterbalance weight as necessary so that the beam and
hanger assembly is just in balance.
8.
Fill up the Oedometer cell with ordinary tap water before applying any load.
9.
The students must determine the lever arm ratio of the apparatus and all
calculations must be shown in your report. .
10.
NB - Before applying any load, ensure that the lever arm is slightly above level.
11.
Adjust the dial gauge to set an initial reading of about 4 (small gauge). This is
done in the event of expanding clay and the rebound (return to normal height) is
greater than the original height. Do not play with the dial gauge needle, ie by
pushing it up and down, as it will seize up very easily, (a dial gauge costs R1220).
12.
The following loading sequences must be adhered to. It is preferable that each
group co-ordinate their Oedometer to initiate compression at the same time, e.g., at
13h30. That means that on each of the following days below, at 13h30, the reading
is taken and the load increased.
Group no’s
Mon
Tues
Wed
(total
(total
mass)
mass)
Thursday
Friday
1,4,7
4 kg
8 kg
16 kg
Set up and
Record all final
2,5,8
5 kg
10 kg
20 kg
perform Falling
gauge readings.
3,6,9
3 kg
6 kg
12 kg
Head
(oedometer and
permeability test
burette)
in Oedometer
Cell
13.
Ensure that the load cell is always filled with clean water each day.
14.
Assume the relative density of the material is 2,68.
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Falling Head setup with Oedometer Cell
Discussion
14.1
What is the main aim of the Oedometer test?
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Page 43
14.2
Where in Civil Engineering would you use the properties that you have described in
you aim? Discuss in particular foundations for structures (7 areas).
14.3
a. What are the advantages and b. disadvantages of this test? Name 5.
14.4
What happens to (1) clayey soil and (2) sandy soil, when a load is applied to it? Name
3 OBSERVABLE facts.
14.5
How would you describe “normally consolidated clay”?
14.6
How would you describe an “over consolidated clay”?
14.7
State typical values for the Coefficient of Consolidation that you would find in
different types of clay or soil. Indicate the correct units.
14.8
Complete all the necessary graphs (as below) and indicate how “T” (time), is
determined. What type of clay sample can be assumed based on your results? (see
comments in KH Head Vol 2).
14.9
Determine the settlement at 1 m below ground level when the normal overburden soil
pressure increases to 250 kPa. There is no drainage below ground, no water table and
the soil is homogenous (no change in its soil properties).
Test Calculation Example
(See p 5.33 in GET301S notes)
From the above graph “t” = (4.5) 2 min=20.25 min
Final height = 18.5 mm (after 5 days)
Therefore Cv (Co-efficient of consolidation) = pi*(H/2) 2/4*t = 3.319 mm2/min
(Convert to m 2 per annum) ie 3.319/10 6 /(*60*24*365)
Final void ratio = h1 (1+e) / h f -1
h f = rebound height
Where:
H= is the final rebound height after time
settlement
Cv   *(
H
2
)2 / 4 *T
T = time read off settlement graph (minutes)
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
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Search the typical Cv values in textbooks, like KH Head Vol 2, and compare your test results
to see what type of soil classification can be ascribed to it.
Figure 1 Oedometer Setup (showing beam ratio). Courtesy KH Head
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Figure 2 Cell Assembly
The cells supplied are of the fixed ring type and a sectional view, with specimen in place, is
given in Fig.2 above, although some cells used this semester will differ slightly in size. The
specimen is taken from a larger sample cut out by means of the cutting ring (1) and the upper
and lower faces trimmed flat. Students are required to take an initial moister sample from the
sample prepared. The weight of the specimen can then be determined. Weigh the ring (1) after
the test. Assemble the cell as described below. (To facilitate assembly, the seal (2) and the
sealing diameter of the cell wall (3) and also the outside (small diameter) of the specimen
cutting ring (4) should be lightly coated with silicone grease). Check that all components are
clean and undamaged. Place the lower porous disc (5) on the cell base (6) centrally inside the
3 studs (7). Fit the locking ring (8) onto the cutting ring (1) containing specimen (9). Gently
lower the locking ring/cutting ring/specimen assembly over the 3 studs (7) until the cutting
ring is sitting on lower porous disc (9). Fit the 3 thumbnuts onto the 3 studs (7) and gently
tighten (excessive force is not required). Gently place the upper porous disc (11) on the
specimen. Locate cap (12) in the upper porous disc. Place cell wall (13) onto the base and
gently press down until it is fully located as shown in Fig. 4. The cell is now ready for
insertion into the consolidation frame.
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OEDOMETER/CONSOLIDATION TEST
TEST NO: ......................... GROUP NO: .........................
DATE:.........................
SAMPLE DIMENSIONS:
Height .......................... mm
Diameter ...................... mm
Area ............................. mm2
Sample Mass ...................... (g)
Relative density (Gs) .................. kg/m3
Gauge divisions: 1 Div. = .................. mm
Time
min.
0.00
1.00
2.25
4.00
6.25
9.00
12.25
16.00
20.00
25.00
30.25
36.00
42.25
49.00
64.00
100.00
121.00
144.00
169.00
1440
2880
4320
5760
Clock
Time
24Hrs
48Hrs
72Hrs
Final
Load
kg
Gauge
Reading
0.0
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
8.0
10.0
11.0
12.0
13.0
37.9
53.7
65.7
75.9
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
Divisions
0.002
0
Settlement
mm
Height
mm
0
Page 47
OEDOMETER/CONSOLIDATION TEST
TEST NO: ......................... GROUP NO: .........................
LOADING
1
DATE:.........................
2
3
HOURS
MASS
LEVER ARM RATIO
FORCE
PRESSURE
FINAL VOID RATIO
HEIGHT
FINAL HEIGHT
LOG PRESSURE
VOID RATIO
COEFFICIENT OF CONSOLIDATION mm/min
COEFFICIENT OF VOLUME DECREASE
INITIAL MOISTURE
TIN No.
Mass of Tin
Mass of Tin and Wet Material
Mass of Tin and Dry Material
Mass of Dry Material
Mass of Water
Moisture Content
Average Moisture Content
FINAL MOISTURE CONTENT
TIN No.
Mass of Tin
Mass of Tin and Wet Material
Mass of Tin and Dry Material
Mass of Dry Material
Mass of Water
Moisture Content
Average Moisture Content
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Test 5: FALLING HEAD
This method is used for measuring the permeability, of
soils of intermediate and low permeability, like silts
and clays; the Falling Head procedure is ideal. In the
Falling Head test a relatively short sample is
connected to a standpipe, which provides both the
head of water and the means of measuring the quantity
of water flowing through the sample. A selection of
several standpipes of different diameters is normally
available for the type of material being tested. The test
requires a reasonable rate of constant flow conditions and must be established before
the test can be started (a 10 % flow difference can be set as a guideline)
IMPORTANT
1.
Do not adjust the wing nuts on top of the cell.
2.
Check, and re-check that there is no entrapped air in the connecting tubes. If any
air bubbles are observed in the manometer or connecting tubes, they can be
removed by applying a low suction to the top end of the standpipe.
3.
Before starting the test, check if constant flow conditions can be maintained. This
is done by the following procedure:
3.1
Adjust the water in the manometer to read about 10 cm (from the top).
3.2
Take a reading (h1) and start the stopwatch.
3.3
After a certain time lapse (say 3 minutes), take another reading (h2).
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3.4
After the same time lapse as in 3.3 (3 minutes), take another reading, h3.
3.5
Calculate if a constant flow condition is present by using the following formula:
h2  h1* h3

3.6
If the calculated value obtained (h21) is not the same or within 10 % to the actual
reading h2, the above procedure must be repeated.
3.7
The following test times must be adhered to:
Test 1
1 minute
Test 2
2 minutes
Test 3
3 minutes
Test 4
5 minutes
Figure 24.1: Schematic of Falling Head test set-up
Discussion
3.8
What is the aim of the Falling Head Permeability test?
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3.9
Where in Civil Engineering would you use the properties that you have described
in your aim?
3.10
What are the advantages and disadvantages of this test when setting up the
apparatus?
3.11
Which known factors influence the permeability of a soil? Name 5
3.12
Classify the soil sample according to its coefficient of permeability and describe
its general soil type. Hint! See KH Head Volume 2, Chapter 10. Also state what
kind of drainage characteristics the soil has.
3.13
State the maximum permeability in m/s of clay that the Department of Water
Affairs and Forestry will allow in the clay-core of an earth-filled dam.
The rate at which water flows through a soil is proportional to the hydraulic
gradient and is expressed by Darcy's Law as:
The coefficient of permeability varies with the type of soil and conditions. It is influenced by:

Size and shape of the soil particles

Temperature

Void ratio

Degree of saturation
Falling Head test: k 
Al
h1
* ln[ ]
at
h2
Round the answer off to the nearest 1*. 001-10 m/s.
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TEST 6: CONSTANT HEAD
The Constant Head procedure is used for the measurement of the permeability of sands
and gravels containing little or no silt. The Constant Head permeability cell is intended
for testing disturbed granular soils, which is re-compacted into the cell either by using a
specified compactive effort, or to achieve a certain dry density.
Permeability of a coarse grained soil can be determined by a constant head permeability
test (AS1289.6.7.1-2001; ASTM D2434), and in a fine grained soil, falling head
Geotechnical Engineering (GET302S) Laboratory Manual Rev 2014
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permeability test (AS1289.6.7.2-2001; ASTM D5856) works the best. In a constant head
permeability test, the total head loss (hL) across a cylindrical soil specimen of length L
and cross sectional area A, is maintained constant throughout the test, and at steady state,
the flow rate (Q) is measured.
During the Constant Head test, water is made to flow through a column of soil under the
application of a pressure difference, which remains constant, i.e. under a constant head.
The amount of water passing through the soil in a known time is measured, and the
permeability of the sample is calculated.
1. NB: Never close the tap that fills up the Constant Head reservoir. If the tap is
closed, the constant flow condition will be influenced. The test will be underway
before students arrive in the laboratory.
2. Do not adjust the wing nuts or the loading piston on top of the constant head cell.
3. Check, and re-check that there is no entrapped air in the connecting tubes. If any
air bubbles are observed in the manometers or connecting tubes, they can be
removed by applying a low suction to the top end of the standpipe.
4. Before starting the test, check if the constant flow conditions can be maintained
by looking at the water levels of the three standpipes. If the water level stays the
same for more than one minute, then the constant flow condition is maintained.
5. Measurements can be done by measuring cylinder or weighed within a glasscanning jar to determine the amount of water discharged from the constant head
cell.
Constant head test: k = QL/Aht
6. Please adhere to the following test intervals:
Test run
Test run 2
Test run 3
Test run 4
2 minutes
4 minutes
6 minutes
1
1 minute
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Figure 25.1: Schematic of Constant Head test set-up
Discussion
1) What is the aim of the Constant Head Permeability test?
2) Where in Civil Engineering would you use the properties that you have described in
your aim?
3) What are the advantages of this test, and b. the disadvantages?
4) Which factors greatly influence the permeability of a soil?
5) Make a neat sketch of a typical sub-surface drainage system/canal that would be found
through a cutting under a road prism. Indicate the use of placing geotextiles to
improve drainage AND provide proper research on the usefulness thereof. Include
percolation rates (l/m 3) for various geotextile products in the Western Cape.
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PERMEABILITY - Constant Head Test
TEST NO: ......................... GROUP NO: .........................
DATE:.........................
Date Tested:
Project Name:
Sample No.:
Visual Classification:
Initial Dry Mass of Soil + Pan (M1) =
g
Length of Soil Specimen, L =
cm
Diameter of the Soil Specimen (Permeameter), D =
cm
Final Dry Mass of Soil + Pan (M2) =
g
Dry Mass of Soil Specimen (M) =
g
cm3
Volume of Soil Specimen (V) =
g/cm3
Dry Density of Soil (ρd) =
Trial
Number
Constant
Head, h
(cm)
Elapsed
Time, t
(seconds)
Outflow
Volume, Q
(cm3)
Water
Temp., T
(°C)
KT
K20
1
2
3
4
Average K20 =....................................................................... cm/sec
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OFFICIAL RECORD OF IN-SERVICE LABORATORY TRAINING
GEOTECHNICAL ENGINEERING GET302S
DECLARATION OF INTENT BY REGISTERED STUDENT
[TO BE SIGNED AND HANDED IN WITH EACH SUBMISSION]
I am submitting this report with the clear intention of having the report
marked for evaluation as a practical component for the subject
Geotechnical Engineering GET301S. I have read the terms and conditions
as set out hereunder and my signature below registers my full cognisance
and agreement.
1. The contents, as contained in this submission, are entirely of my own
work, being generated out of original research and study.
2. No part of this submission has been copied from fellow group
members, photo-stated with out permission or plagiarised from other
authors without their consent.
3. The contents of this submission have also not been generated from
reports previously handed in by past students.
4. I have read the laboratory introductory guidelines in the manual
handed to me in the beginning of the semester.
SIGNED
STUDENT NUMBER_
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