Soil mechanics 2 (geotech engg) lab report

CED, UET-P Muhammad Bilal
Soil Mechanics II (Geotechnical Engineering)
Lab Report

GEOTECH-II CE-313L Group Report
Civil Department, UET Peshawar 1 | P a g e
Abstract:
Geotechnical Engineering is the specialty of Civil Engineering which deals with the
property and behavior of soil and rock in engineering purposes.
To obtain different properties of soil, laboratory tests are performed on collected
disturbed and undisturbed soil samples, while field tests are performed on sub-soil at in-situ
condition following mainly standard ASTM methods. The first step in any geotechnical
engineering project is to identify and describe the subsoil condition. For example, as soon as a
ground is identified as gravel, engineer can immediately form some ideas on the nature of
problems that might be encountered in a tunneling project. In contrast, a soft clay ground is
expected to lead to other types of design and construction considerations. Therefore, it is useful
to have a systematic procedure for identification of soils even in the planning stages of a
project. Soils can be classified into two general categories: (1) coarse grained soils and (2) fine
grained soils. Usually coarse-grained soils are sand, gravel, cobble and boulder, while fine-
grained soils are silt and clay.
The following tests was performed by the students of Civil Engineering Department
U.E.T Peshawar (the list of experiments can be seen in table of contents) under the supervision
of Sir Engr. Zia Ullah.
The main purpose of this lab was to investigate different types of soils through different
tests and to compare them with the standards mostly ASTM. Soil behaves differently in
different conditions. Field identification tests of soil and laboratory tests like direct shear test
may be performed on collected disturbed soil samples, unconfined compression test,
consolidation test and triaxial test may be performed on collected undisturbed soil samples
according to ASTM (American Standards for Testing Materials) methods.
This Lab manual was prepared with the help of ASTM and ―Engineering Properties
of Soil based on Laboratory Testing.

Contents:
Experiment 1: “Direct shear test”..................................................................5
Objective:..................................................................................................................................5
Need and scope:........................................................................................................................5
Planning and organization:.....................................................................................................5
Knowledge of equipment:........................................................................................................5
Procedure: ................................................................................................................................6
Parts of Apparatus:..................................................................................................................7
Data:..........................................................................................................................................8
Graphs: ..................................................................................................................................10
General Remarks:..................................................................................................................11
Experiment # 2...................................................................................12
“To Determine the unconfined compressive strength of a cohesive
soil sample.” .......................................................................................12
Objective:................................................................................................................................12
Need and scope:......................................................................................................................12
Procedure: ..............................................................................................................................13
Calculations:...........................................................................................................................13
Data:........................................................................................................................................14
Graph:.....................................................................................................................................14
Experiment # 3...................................................................................15
“Unconsolidated-Undrained Triaxial Compression Test on
Cohesive Soils”...................................................................................15
Objective:................................................................................................................................15
Need And Scope: ....................................................................................................................15

Apparatus ...............................................................................................................................15
Procedure: ..............................................................................................................................16
Results And Calculations ......................................................................................................16
Table: ......................................................................................................................................17
GRAPH:..................................................................................................................................19
Result: .....................................................................................................................................19
Experiment # 4: Shear Strength of Soil by Vane Shear Test ...........20
Objective:................................................................................................................................20
Apparatus:-.............................................................................................................................20
Procedure of Vane Shear Test:-............................................................................................21
Observations and Calculations of Vane Shear Test............................................................22
Result of Vane Shear Test:....................................................................................................23
Advantages of Vane Shear Test:...........................................................................................23
Drawbacks of Vane Shear Test.............................................................................................23
Experiment # 5 “Consolidation Test On Soil”...........................................24
Objective:................................................................................................................................24
Significance and Use:.............................................................................................................24
Apparatus Required for Consolidation Test:......................................................................24
Consolidation Test Procedure: .............................................................................................25
Observations for Consolidation Test of Soil:.......................................................................27
Calculations for Consolidation Test of Soil:........................................................................28
Graphs to be plotted:.............................................................................................................28
Results of Consolidation Test of Soil: ..................................................................................31
Experiment # 6 “Standard Penetration Test (SPT)”.............................32
ASTM designation...................................................................................................................32
Objective:................................................................................................................................32

Significance and Use:.............................................................................................................32
Standard Penetration Test (SPT) Theory.................................................................................32
Apparatus Required for Consolidation Test:......................................................................32
Test Procedure:......................................................................................................................33
Corrections in Standard Penetration Test: .........................................................................33
1. Dilatancy Correction:...........................................................................................................33
2. Overburden Pressure Correction:.........................................................................................34
Advantages of Standard Penetration Test................................................................................34
Disadvantages of Standard Penetration Test............................................................................34
Standardized SPT Data Corrections:...................................................................................35
Observations for Standard Penetration Test:.....................................................................36
Bearing Capacity of Soil:- .....................................................................................................37
1. Meyerhof’s Equations:..................................................................................................37
2. Bowles’ Equations:.......................................................................................................38
Experiment: Plate Load Test...............................................................39
ASTM Designation: D 1194-94..............................................................................39
Objective:................................................................................................................................39
Need and Scope:.....................................................................................................................39
Apparatus:..............................................................................................................................39
Procedure: ..............................................................................................................................40
Calculation of Bearing Capacity from Plate Load Test:....................................................41
Bearing Capacity Calculation for Clayey Soils .......................................................................41
Bearing Capacity Calculation for Sandy Soils.........................................................................41
Calculation of Foundation Settlement from Plate Load Test: .................................................41
Foundation Settlement Calculation on Clayey Soils ...............................................................41
Foundation Settlement Calculation on Sandy Soils.................................................................42
Calculations:...........................................................................................................................42
Conclusion:.............................................................................................................................42
References: 46

Experiment 1: “Direct shear test”
Objective:
To determine the shearing strength of the soil using the direct shear apparatus.
Need and scope:
In many engineering problems such as design of foundation, retaining walls, slab bridges,
pipes, sheet piling, the value of the angle of internal friction and cohesion of the soil involved
are required for the design. Direct shear test is used to predict these parameters quickly. The
laboratory report cover the laboratory procedures for determining these values for cohesion
less soils.
Planning and organization:
Apparatus:
1. Direct shear box apparatus
2. Loading frame (motor attached).
3. Dial gauge.
4. Proving ring.
5. Tamper.
6. Straight edge.
7. Balance to weigh upto 200 mg.
8. Aluminum container.
9. Spatula.
Knowledge of equipment:
Strain controlled direct shear machine consists of shear box, soil container, loading unit,
proving ring, dial gauge to measure shear deformation and volume changes. A two piece square
shear box is one type of soil container used.
APPARATUS

A proving ring is used to indicate the shear load taken by the soil initiated in the shearing plane.
Procedure:
1. Check the inner dimension of the soil container.
2. Put the parts of the soil container together.
3. Calculate the volume of the container. Weigh the container.
4. Place the soil in smooth layers (approximately 10 mm thick). If a dense sample is desired
tamp the soil.
5. Weigh the soil container, the difference of these two is the weight of the soil. Calculate the
density of the soil.
6. Make the surface of the soil plane.
7. Put the upper grating on stone and loading block on top of soil.
8. Measure the thickness of soil specimen.
9. Apply the desired normal load.
10. Remove the shear pin.
11. Attach the dial gauge which measures the change of volume.
12. Record the initial reading of the dial gauge and calibration values.
13. Before proceeding to test check all adjustments to see that there is no connection between
two parts except sand/soil.
14. Start the motor. Take the reading of the shear force and record the reading.
15. Take volume change readings till failure.
16. Add 5 kg normal stress 0.5 kg/cm2
and continue the experiment till failure
17. Record carefully all the readings. Set the dial gauges zero, before starting the experiment

Parts of Apparatus:
1. Direct shear box apparatus, and Loading frame (motor attached)
2. Dial gauge for vertical deformation measurement
3. Dial gauge for horizontal deformation measurement
4. Proving ring for Shear force measurement. Loads are kept in loading frame for application
of normal stress
5. Components of shear box with porous stone, filter paper etc.

Data:
1) Normal stress 0.5 kg/cm2 L.C=0.01 P.R.C=0.425
Horizontal
Gauge
Reading
Proving
Ring
Reading
Horizontal/shear
Deformation
Shear
Force (kg)
Shear Stress
0 0 0 0 0.000
50 16 0.5 6.8 0.241
100 21 1 8.925 0.316
150 26 1.5 11.05 0.391
200 29 2 12.325 0.436
250 33 2.5 14.025 0.496
300 35 3 14.875 0.526
350 37 3.5 15.725 0.556
400 38 4 16.15 0.571
450 39 4.5 16.575 0.586
500 40 5 17 0.601
550 40 5.5 17 0.601
600 41 6 17.425 0.616
650 41 6.5 17.425 0.616
700 41 7 17.425 0.616
750 42 7.5 17.85 0.631
800 46 8 19.55 0.692
850 46 8.5 19.55 0.692
900 46 9 19.55 0.692
950 46 9.5 19.55 0.692
1000 45 10 19.125 0.677
Horizontal
Gauge
Reading
Proving Ring
Reading
Horizontal/shear
Deformation
Shear Force
(kg)
Shear Stress
50 13 0.5 5.525 0.195
100 17 1 7.225 0.256
150 20 1.5 8.5 0.301
200 23 2 9.775 0.346
250 24 2.5 10.2 0.361
300 26 3 11.05 0.391
350 27 3.5 11.475 0.406
400 27 4 11.475 0.406
450 28 4.5 11.9 0.421
500 28 5 11.9 0.421
550 29 5.5 12.325 0.436
600 29 6 12.325 0.436
650 29 6.5 12.325 0.436
700 29 7 12.325 0.436

Horizontal
Gauge reading
Proving Ring
Reading
Horizontal/shear
Deformation
Shear
Force (kg)
Shear Stress
50 14 0.5 5.95 0.210
100 16 1 6.8 0.241
150 17 1.5 7.225 0.256
200 17 2 7.225 0.256
250 18 2.5 7.65 0.271
300 19 3 8.075 0.286
350 19 3.5 8.075 0.286
400 20 4 8.5 0.301
450 20 4.5 8.5 0.301
500 21 5 8.925 0.316
550 21 5.5 8.925 0.316
600 21 6 8.925 0.316
650 21 6.5 8.925 0.316
700 22 7 9.35 0.331
750 23 7.5 9.775 0.346
800 23 8 9.775 0.346
850 24 8.5 10.2 0.361
900 25 9 10.625 0.376
950 25 9.5 10.625 0.376
1000 24 10 10.2 0.361
Horizontal
Gauge Reading
Proving Ring
Reading
Horizontal/shear
Deformation
Shear
Force
(kg)
Shear
Stress
50 26 50 11.05 0.391
100 40 100 17 0.601
150 52 150 22.1 0.782
200 61 200 25.925 0.917
250 69 250 29.325 1.037
300 74 300 31.45 1.112
350 79 350 33.575 1.188
400 83 400 35.275 1.248
450 87 450 36.975 1.308
500 89 500 37.825 1.338
550 90 550 38.25 1.353
600 90 600 38.25 1.353
650 89 650 37.825 1.338
700 87 700 36.975 1.308
750 86 750 36.55 1.293
800 84 800 35.7 1.263
850 83 850 35.275 1.248
900 82 900 34.85 1.233
950 81 950 34.425 1.218

Graphs: Graph # 1
Graph # 2
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9 9.5 10
ShearStress()KPa)
Horizontal Displacement (mm)
Shear Stress vs Horizontal Displacement Curve
Normal
Stress 0.5
kg/cm^2
Normal
Stress 1
kg/cm^2
Normal
Stress 1.5
kg/cm^2
Normal
Stress 2
kg/cm^2
y = 0.3786x + 0.2335
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0 0.5 1 1.5 2 2.5
Shearstress(Kg/cm^2)
Normal Stress (kg/cm^2)
Shear Stress vs Normal Stress

Conclusion:
 Cohesion = 0.2335
 Internal friction angle = 21o
General Remarks:
1. In the shear box test, the specimen is not failing along its weakest plane but along a
predetermined or induced failure plane i.e. horizontal plane separating the two halves of the
shear box. This is the main drawback of this test. Moreover, during loading, the state of stress
cannot be evaluated. It can be evaluated only at failure condition i.e. Mohr’s circle can be drawn
at the failure condition only. Also failure is progressive.
2. Direct shear test is simple and faster to operate. As thinner specimens are used in shear
box, they facilitate drainage of pore water from a saturated sample in less time. This test is also
useful to study friction between two materials one material in lower half of box and another
material in the upper half of box.
3. The angle of shearing resistance of sands depends on state of compaction, coarseness of
grains, particle shape and roughness of grain surface and grading. It varies between 28o
(uniformly graded sands with round grains in very loose state) to 46o
(well graded sand with
angular grains in dense state).
4. The volume change in sandy soil is a complex phenomenon depending on gradation,
particle shape, state and type of packing, orientation of principal planes, principal stress ratio,
stress history, magnitude of minor principal stress, type of apparatus, test procedure, method
of preparing specimen etc. In general loose sands expand and dense sands contract in volume
on shearing. There is a void ratio at which either expansion contraction in volume takes place.
This void ratio is called critical void ratio. Expansion or contraction can be inferred from the
movement of vertical dial gauge during shearing.
5. The friction between sand particles is due to sliding and rolling friction and interlocking
action.
 The ultimate values of shear parameter for both loose sand and dense sand
approximately attain the same value so, if angle of friction value is calculated at
ultimate stage, slight disturbance in density during sampling and preparation of test
specimens will not have much effect.
SHEAR FAILURE IN SOILS

Experiment # 2:
“To determine the unconfined compressive strength of
a cohesive soil sample.”
Objective:
The aim of this laboratory test is to determine the unconfined compressive strength
of a cohesive soil.
Need and scope:
This test method covers the determination of the unconfined compressive strength of cohesive
soil in the intact, remolded, or reconstituted condition, using strain-controlled application of
the axial load. This test method also provides an approximate value of the strength of cohesive
soils in terms of total stresses.
Apparatus:
 Loading frame
 Proving ring
 Deformation Indicator
 Sample Extruder
 Specimen trimming
 Remolding apparatus,
 Weighing balance
 Microwave oven
 Water content cans
APPARATUS
Proving ring
Deformation indicator
Motor
Top
Conical
Plate
Frame
Bottom
Conical
Plate

Procedure:
• Place the specimen in the loading device so that it is centered on the bottom platen.
• Adjust the loading device carefully so that the upper platen just makes contact with
the specimen.
• Zero the deformation indicator or record the initial reading of the electronic
deformation device.
• Apply the load so as to produce an axial strain at a rate of 1⁄2 to 2 %⁄min.
Record load, deformation, and time values at sufficient intervals to define the shape
of the stress-strain curve (usually 10 to 15 points are sufficient).
• The rate of strain should be chosen so that the time to failure does not exceed about
15 min
• Continue loading until the load values decrease with increasing strain, or until 15
% strain is reached
• Determine the water content of the test specimen using the entire specimen, unless
representative trimmings are obtained for this purpose, as in the case of undisturbed
specimens
Calculations:
Axial Strain Formula:
e = (ΔL /L0) × 100
Area Correction:
Ac = A0 / (1- (e /100)
Compressive stress, σc:
σc = P/Ac

Data:
Least Count (L.C) = 0.01 mm
Proving Ring Constant (PRC) = 0.218 kg/division
Dial
Gauge
Reading
Deformation
(mm)
Proving
Ring
Reading
Unit
Strain,
e (%)
Corrected
Area, Ac
(cm2
)
Load
(kg)
Stress
(kg/cm2
)
0 0 0 0.0000 9.3977 0 0.0000
50 0.5 15 0.0746 9.4047 3.27 0.3477
100 1 22 0.1493 9.4118 4.796 0.5096
150 1.5 27 0.2239 9.4188 5.886 0.6249
200 2 30 0.2985 9.4258 6.54 0.6938
250 2.5 32 0.3731 9.4329 6.976 0.7395
300 3 32 0.4478 9.4400 6.976 0.7390
350 3.5 27 0.5224 9.4471 5.886 0.6231
400 4 19 0.5970 9.4541 4.142 0.4381
450 4.5 13 0.6716 9.4613 2.834 0.2995
500 5 8 0.7463 9.4684 1.744 0.1842
Graph:
Result:
Unconfined compressive strength (qu) = 0.7146 kg/cm2
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0
AxialStress(kg/cm2)
Axial Strain (%)
Relationship B/w Stress and Axial Strain
Failure pointMaximum Axial Stress0.7146

Experiment # 3
“Unconsolidated-Undrained Triaxial Compression
Test on Cohesive Soils”
Objective:
To Determine the Unconsolidated-Undrained Triaxial compression of a cohesive soil sample.
Need and scope:
This test method covers determination of the strength and stress-strain relationships of a
cylindrical specimen of either undisturbed or remolded cohesive soil. Specimens are subjected
to a confining fluid pressure in a triaxial chamber. No drainage of the specimen is permitted
during the test. The specimen is sheared in compression without drainage at a constant rate of
axial deformation (strain controlled).
Apparatus
 Axial Load-Measuring Device
 Axial Loading Device
 Triaxial Compression Chamber
 Axial Load Piston
 Pressure Control Device
 Specimen Cap and Base
 Deformation Indicator
 Rubber Membrane
 Timer
 Balances
 Specimen Size Measurement Devices
 Sample Extruder
APPARATUS
Miscellaneous:
Apparatus—Specimen trimming and carving
tools including a wire saw, steel straightedge,
miter box and vertical trimming lathe,
apparatus for preparing compacted specimens,
remolding apparatus, water content cans, and
data sheets shall be provided as required.

Procedure:
 The loading ram was brought into contact with the loading cap. Then cautiously the
TRIAXIAL cell was raised to bring the loading ram in contact with the proving ring.
(This is shown by small deflection, maybe 2 divisions, as observed from the dial gauge).
 A cell pressure was then applied, this was done by opening the cell pressure supply
valve.
 Proper adjustment was giving to the proving ring’s position, to make contact with the
loading ram, then zero the dial gauge.
 The strain rate was set to 1.25 mm/min, after this the machine was turned on.
 The proving ring dial gauge readings (divisions) were recorded subsequent to the
vertical defection.
 The machine is to be switched off when either the proving ring gauge goes backwards
or if a 16mm deformation is achieved. In this lab test, the machine was switched off
when the proving ring gauge started going backwards.
 The cell pressure valve was closed and drained of water into the water cylinder.
 Then cautiously the cell was lowered and the loading ram discharged. Then the Perspex
cylinder top was removed and the soil sample extracted.
 The whole tested soil specimen was then used to determine a water content.
 Then the above steps were repeated at the desired cell pressures.
Results And Calculations
Axial Strain (∈)
∈ = ΔH/ H0
Where,
HL = change in height of specimen as read from deformation indicator, mm (in.)
H0 = initial height of specimen minus any change in length prior to loading, mm (in.)

Average cross-sectional area
Ac = A0 / (1− ∈/100)
Where,
Ac = average cross-sectional area, m2 and
Ao = initial average cross-sectional area of the specimen,
Deviator stress:
For a given applied load,
(σ1−σ3) = P / Ac
Where:
Ac = initial average cross-sectional area of the specimen, m2 (in.2)
P = given applied axial load (corrected for uplift and piston friction, if required), kPa (psi).
Triaxial Compression Test Data:
Diameter of specimen= D0=2.50 in
Initial height of specimen= H0 =5.82 in
Chamber pressure= σ3 =10 psi
Rate of Axial strain= 0.02 in/min
Proving ring calibration= 6000 lb/min
Initial Area = 4.90625
Sensitivity = (qu for undisturbed sample)/ (qu for remoulded sample).

Table: Observed and calculated readings for specimen
Elapsed
time
(min)
(1)
Deformation
Dial (ΔL)
(2)
Proving
Ring Dial
(3)
Axial
strain
(e)
(4)
Corrected
Area
(5)
Applied Axial load
(6)=3×calibration
factor
Unit Axial
Load
(Deviator
stress)
(7)=6/5
0.00 0 0 0 4.91 0 0
0.88 0.005 0.0012 0.0009 4.91 7.2 1.5
1.75 0.01 0.0025 0.0017 4.91 15 3.1
2.63 0.015 0.0037 0.0026 4.92 22.2 4.5
3.50 0.02 0.0053 0.0034 4.92 31.8 6.5
4.38 0.025 0.0066 0.0043 4.93 39.6 8.0
5.25 0.05 0.014 0.0086 4.95 84 17.0
6.13 0.075 0.0201 0.0129 4.97 120.6 24.3
7.00 0.1 0.0256 0.0172 4.99 153.6 30.8
7.88 0.125 0.0294 0.0215 5.01 176.4 35.2
8.75 0.15 0.0321 0.0258 5.04 192.6 38.2
9.63 0.175 0.0337 0.0301 5.06 202.2 40.0
10.50 0.2 0.0331 0.0344 5.08 198.6 39.1
11.25 0.225 0.0305 0.0387 5.10 183 35.9

GRAPH:
Result:
Major Principal Stress at failure as
𝝈𝟏 = 𝝈𝟑 + ∆𝝈
𝝈𝟏 = 𝟏𝟎 + 𝟒𝟎
𝝈𝟏 = 𝟓𝟎psi
Unconsolidated-Undrained compressive strength = 40psi
Major Principal Stress (σ1) at failure = 50psi
The principal stress ratio: σ1/σ3 = 5
Unconsolidated-Undrained Shear strength = 20psi
0
5
10
15
20
25
30
35
40
45
0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045
Stress(lb/in^2)
Axial Strain (in/in)
Stress-Strain Curve
From the Graph, obtain the max
value of Δσ at failure point (Δσ = σf)

Experiment # 04: “Shear Strength of Soil by Vane Shear
Test”
Objective: Vane shear test is used to determine the undrained shear strength of soils
especially soft clays. This test can be done in laboratory or in the field directly on the ground.
Vane shear test gives accurate results for soils of low shear strength (less than 0.3 kg/cm2).
Apparatus:-
Apparatus required for vane shear test are:
1. Vane shear apparatus
2. Soil specimen container
3. Vernier calipers.
Fig 2: Steel Rod with Vanes
Figure: Vane Shear Apparatus
Vane shear apparatus consists high
tensile steel rod to which four steel
blades (vanes) are fixed at right angles
to each other at the bottom of rod

Procedure of Vane Shear Test:-
Test procedure of vane shear test contains following steps:
 Clean the vane shear apparatus and apply grease to the lead screw for better movement
of handles.
 Take the soil specimen in container which is generally 75 mm in height and 37.5 mm
in diameter.
 Level the soil surface on the top and mount the container on the base of vane shear test
apparatus using screws provided.
 Lower the vane gradually into the soil specimen until the top of vane is at a depth of 10
to 20 mm below the top of soil specimen.
Fig 3: Lowering Vane into the Soil Specimen
 Note down the reading of pointer on circular graduated scale which is initial reading.
 Rotate the vane inside the soil specimen using torque applying handle at a rate of
0.1o
per second.

 When the specimen fails, the strain indicator pointer will move backwards on the
circular graduated scale and at this point stop the test and note down the final reading
of pointer.
 The difference between Initial and final readings is nothing but the angle of torque.
 Repeat the procedure on two more soil specimens and calculate the average shear
strength value.
 Measure the diameter and height of vane using Vernier calipers.
 Sensitivity of given soil sample is determined by repeating the above test procedure on
remolded soil which is nothing but soil obtained after rapid stirring of vane in the above
test.
Sensitivity of soil = undisturbed shear strength/ remolded shear strength.
Observations and Calculations of Vane Shear Test
Shear strength of given soil sample is calculated from below observations.
 Diameter of vane, D = 3.75 cm
 Height of vane, H = 7.5 cm
 Torque, T = (Spring constant /180)*(initial reading-final reading)
Shear strength of soil (S) is calculated from below formula.

S.
No
Initial
Reading
(Deg)
Final
Reading
(Deg)
Difference
(Deg)
Spring
Constant
(Kg-cm)
Torque
(T)
G = 1/π ×
(D2H/2+D3/6)
Shear
Strength
(S=T*G)
(Kg-cm-2
)
1 196 188 8 4.98 0.221 0.03258 0.00721
2 200 191 9 4.98 0.249 0.03258 0.00811
3 195 186 9 4.98 0.249 0.03258 0.00811
4 87 75 12 3.19 0.213 0.03258 0.00693
5 90 79 11 3.19 0.195 0.03258 0.00635
6 88 77 11 3.19 0.195 0.03258 0.00635
Result of Vane Shear Test:
Avg. Shear strength of soil specimen = 0.00718 kg/cm2
.
Advantages of Vane Shear Test:
Advantages of vane shear test are as follows:
 Vane shear test is easy and quick.
 This test can be performed either in laboratory or in the field directly on the ground.
 In-situ vane shear test ideal for the determination of undrained shear strength of non-
fissured, fully saturated clay.
 Shear strength of soft clays at greater depths can also be found by vane shear test.
 Sensitivity of soil can also be determined using vane shear test results of undisturbed
and remolded soil samples.
Drawbacks of Vane Shear Test
Drawbacks of vane shear test are as follows:
 Vane shear test is not suitable for clays which contain sand or silt laminations in it.
 It cannot be conducted on the fissured clay.
 If the failure envelope is not horizontal, vane shear test does not give accurate results.

EXPERIMENT # 5 “CONSOLIDATION TEST ON SOIL”
ASTM designation: ASTM D2435 / D2435M - 11
Objective:
To Determine the rate and magnitude of settlement in soils.
Significance and Use:
The data from the consolidation test are used to estimate the magnitude and rate of both
differential and total settlement of a structure or earth fill. Estimates of this type are of key
importance in the design of engineered structures and the evaluation of their performance.
The test results can be greatly affected by sample disturbance. Careful selection and preparation
of test specimens is required to reduce the potential of disturbance effects.
Apparatus Required for Consolidation Test:
 Consolidometer or Odometer
 Consolidation ring
 Two porous stones
 Two filter papers
 Loading pad
 Stop watch
 Vernier calipers
 Oven
 Water reservoir
 Dial gauge (accuracy of 0.002mm)
 Knife or spatula or fine metal wires
 Weighing balance (accuracy of 0.01g)
Parts of Consolidometer

Consolidation Test Procedure:
Test procedure for consolidation test of soil contains following steps:
1. First step is to collect the soil specimen using consolidation metal ring. The ring should be
clean and dried and its weight, inner diameter and height are measured using weighing balance
and calipers respectively.
2. Now press the metal ring into the soil sample using hands and it is taken out with soil specimen.
3. The soil specimen should project about 10 mm on either side of metal ring.
4. Now trim the excess soil content on top and bottom of the rings using Knife or spatula or fine
metal wires. This excess soil can be used to measure the water content of soil sample.
5. Make sure that the ring should not contain any soil on its outer part and weight the metal ring
with soil specimen.
6. Take two porous stones and saturate them by boiling (15 minutes) or by submerging (4 to 8
hours) in distilled water.
7. Assemble the Consolidometer. Place the parts of Consolidometer from bottom to top in the
order beginning with bottom porous stone, filter paper, specimen ring, filter paper and top
porous stone.
Arrangement of Consolidometer Parts Dial Gauge
8. Place the loading pad on the top porous stone and lock the Consolidometer using metal screws
provided.
9. Mount the whole assembly on the loading frame and center it such that the load applied is axial.

10. Arrange the dial gauge in a position in such a way that it should allow sufficient space for
swelling of soil specimen.
11. Water reservoir is connected to the mounted assembly to saturate the soil. The water level in
the water reservoir should be of same level as the soil specimen.
12. Now apply the initial trail load which should not allow any swelling in the soil. In general 5
kN/m2
initial load applied for ordinary soils and 2.5 kN/m2
is applied for very soft soils.
13. Leave the load until there is no change in dial gauge reading or for 24 hours and note down the
final reading of dial gauge for initial load.
14. First load increment of 10 kN/m2
is applied and start the stop watch immediately and note down
the readings of dial gauge at various time intervals. In general, readings are taken at 0.25, 1,
2.5, 4, 6.25, 9, 16, 25, 30 minutes, 1, 2, 4, 8, 24 hrs.
15. In general primary consolidation of soil (90% of consolidation) is reached within 24 hours.
Hence readings are noted up to 24 hours.
Applying Loads on Consolidometers
16. Next apply the second load increment of 20 kN/m2
and repeat same procedure as said in 14 th
step.
17. Similarly apply the load increments 50, 100, 200, 400 and 800 kN/m2
and repeat the same
procedure and note down the readings.
18. When values of last load increment are noted, now reduce the load to ¼ of the last load value
and leave it for 24 hours. At this point note down the dial gauge reading. Reduce the load again

and again and repeat the procedure until the load gets 10 kN/m2
. At every point note down the
final gauge readings.
19. Now remove the assembly from loading frame and dismantle it.
20. Take out the specimen ring and wipe out the excess water and Weigh the specimen ring and
note down.
21. Finally Put the specimen in oven and determine the dry weight of specimen.
Observations for Consolidation Test of Soil:
Observation of consolidation test are
o Specific Gravity of Solids, G = 2.75
Table 1: Dial gauge readings for different loads at different times
Intensity of load (kg/cm) 0.4 0.8 1.6 3.2 6.4 12.8
Time Interval (vertical)
0 minutes 0 294 558 909 1178 1448
15 Seconds 175 462 768 1054 1312 1560
30 Seconds 190 481 800 1072 1330 1575
1.0 minutes 203 498 822 1092 1347 1593
2 minutes 217 513 839 1111 1365 1614
4 minutes 229 527 852 1125 1381 1633
8 minutes 241 540 864 1137 1394 1648
15 minutes 251 541 878 1144 1403 16662
30 minutes 265 541 885 1152 1412 1669
1 hour 270 542 894 1159 1418 1675
2 hours 278 545 900 1161 1428 1680
4 hours 283 550 902 1165 1431 1684
8 hours 288 555 904 1167 1433 1688
24 hours 294 558 909 1178 1448 1699

Calculations for Consolidation Test of Soil:
Height of solids,
Height Voids, Hv = H – Hs
Void ratio, e = Hv / Hs
Table 2: Void ratio calculation for different pressure intensities
Intensity
Pressure
( kN/m2
)
Initial
Dial
Reading
Final
Dial
Reading
Initial
Height
Ho(mm)
∆H
(mm)
Specimen
height, H
Height
of
solids,
Hs
Height
of
voids,
Hv
Void
Ratio, e
0.4 0 294 20 0.882 19.118 9.4 9.718 1.0338
0.8 294 558 20 1.674 18.326 9.4 8.926 0.9496
1.6 558 909 20 2.727 17.273 9.4 7.873 0.8375
3.2 909 1178 20 3.534 16.466 9.4 7.066 0.7517
6.4 1178 1448 20 4.344 15.656 9.4 6.256 0.6655
12.8 1448 1699 20 5.097 14.903 9.4 5.503 0.5854
Graphs to be plotted:
o Dial gauge reading Vs. square root of time to determine the coefficient of consolidation (Cv).
o Final void ration Vs logarithmic of effective stress – To determine Compression Index (Cc).

Graphs:
From graph e1=0.91 and e2=0.69 and p1 = 1, p2 = 5.
𝑚 𝑣 =
𝛥𝑒
𝛥𝑝 (1 + 𝑒1)
So value of mv is 0.8197
1, 0.91
5, 0.69
0.5
0.6
0.7
0.8
0.9
1
1.1
0.1 1 10 100
voidratio(e)
Log of Pressure
DETERMINATION OF mv and Cc
e1
e2
P2
0
50
100
150
200
250
300
350
0 5 10 15 20 25 30 35 40
DialGaugeReading
Square-root of Time
DETERMINATION OF Cv for 0.4 kg/cm2
690 793
P1
190
2.9

200
250
300
350
400
450
500
550
600
0 5 10 15 20 25 30 35 40
DialGaugeReading
Square-root of Time
1
500
550
600
650
700
750
800
850
900
950
0 5 10 15 20 25 30 35 40
DialGaugeReading
Square-root of Time
1

Results of Consolidation Test of Soil:
Consolidation Test of soils gives the following Results
o Coefficient of compression (mv), mv = 0.819
o Compression Index (Cc), 𝑪 𝒄 =
∆𝒆
∆𝒍𝒐𝒈𝒑
= 0.314
o Coefficient of consolidation, (Cv) = [(0.848) Hdr
2] / t90 = (0.848 × 16.9572 ) / 2.9
1100
1150
1200
1250
1300
1350
1400
1450
1500
0 5 10 15 20 25 30 35 40
DialGaugeReading
Square-root of Time
2
1400
1450
1500
1550
1600
1650
1700
1750
0 5 10 15 20 25 30 35 40
DialGaugeReading
Square-root of Time
2.2

Experiment # 6: “Standard Penetration Test (SPT)”
ASTM designation: D1586 − 11
Objective:
To find the penetration Resistance of soil and determine in-situ properties of cohesion less
soils.
Significance and Use:
The test is extremely useful for determining the relative density and the angle of shearing
resistance of cohesion less soils. It can also be used to determine the unconfined compressive
strength of cohesive soils.
Standard Penetration Test (SPT) Theory
The standard penetration test is an in-situ test that is coming under the category of penetrometer
tests. The standard penetration tests are carried out in borehole. The test will measure the
resistance of the soil strata to the penetration undergone. A penetration empirical correlation is
derived between the soil properties and the penetration resistance.
The data from the consolidation test are used to estimate the magnitude and rate of both
differential and total settlement of a structure or earth fill. Estimates of this type are of key
importance in the design of engineered structures and the evaluation of their performance.
The test results can be greatly affected by sample disturbance. Careful selection and preparation
of test specimens is required to reduce the potential of disturbance effects.
Apparatus Required for Consolidation Test:
The requirements to conduct SPT are:
 Standard Split Spoon Sampler
 Drop Hammer weighing 63.5kg
 Guiding rod
 Drilling Rig.
 Driving head (anvil).
 Tripod assembly
 Rope
 Pulleys

Test Procedure:
The test is conducted in a bore hole by means of a standard split spoon sampler. Once
the drilling is done to the desired depth, the drilling tool is removed and the sampler is placed
inside the bore hole.
By means of a drop hammer of 63.5kg mass falling through a height of 750mm at the rate of
30 blows per minute, the sampler is driven into the soil. This is as per IS -2131:1963.
The number of blows of hammer required to drive a depth of 150mm is counted. Further it is
driven by 150 mm and the blows are counted.
Similarly, the sampler is once again further driven by 150mm and the number of blows
recorded.
The number of blows recorded for the first 150mm not taken into consideration.
The number of blows recorded for last two 150mm intervals are added to give the standard
penetration number (N).
In other words,
N = No: of blows required for 150mm penetration beyond seating drive of 150mm.
 If the number of blows for 150mm drive exceeds 50, it is taken as refusal and the test
is discontinued. The standard penetration number is corrected for dilatancy correction
and overburden correction.
Corrections in Standard Penetration Test:
Before the SPT values are used in empirical correlations and in design charts, the field
‘N’ value have to be corrected as per IS 2131 – 1981. The corrections are:
1. Dilatancy Correction
2. Overburden Pressure Correction
 Note: For cohesive soil there is no need for overburden pressure correction
1. Dilatancy Correction:
Silty fine sands and fine sands below the water table develop pore water pressure which is not
easily dissipated. The pore pressure increases the resistance of the soil and hence the
penetration number (N).
Terzaghi and Peck (1967) recommend the following correction in the case of silty fine sands
when the observed value is N exceeds 15.
The corrected penetration number, NC = 15 + 0.5 (NR -15)

Where NR is the recorded value and NC is the corrected value.
If NR less than or equal to 15, then Nc = NR
2. Overburden Pressure Correction:
From several investigations, it is proven that the penetration resistance or the value
of Nis dependent on the overburden pressure. If there are two granular soils with relative
density same, higher ‘N’ value will be shown by the soil with higher confining pressure.
With the increase in the depth of the soil, the confining pressure also increases. So the value of
‘N’ at shallow depth and larger depths are underestimated and overestimated respectively.
Hence, to account this the value of ‘N’ obtained from the test are corrected to a standard
effective overburden pressure.
The corrected value of ‘N’ is
NC = CN N
Here CN is the correction factor for the overburden pressure.
Advantages of Standard Penetration Test
The advantages of standard penetration test are:
1. The test is simple and economical
2. Actual soil behavior is obtained through SPT values
3. The method helps to penetrate dense layers and fills
4. Test can be applied for variety of soil conditions
5. The test provides representative samples for visual inspection, classification tests and
for moisture content.
Disadvantages of Standard Penetration Test
The limitations of standard penetration tests are:
1. The results will vary due to any mechanical or operator variability or drilling
disturbances.
2. Test is costly and time consuming.
3. The samples retrieved for testing is disturbed.
4. The test results from SPT cannot be reproduced
5. The application of SPT in gravels, cobbles and cohesive soils are limited

Standardized SPT Data Corrections:
SPT data can be corrected for a number of site specific factors to improve its
repeatability. Burmister’s 1948 energy correction assumed that the hammer percussion system
is 100% efficient (a 140-lb hammer dropping 30 inches = 4,200 ft-lbs raw input energy). In
A.W. Skempton, 1986, Standard Penetration Test procedures and the Effects in Sands of
Overburden Pressure, Relative Density, Particle Size, and Aging and over consolidation:
Geotechnique, the procedures for determining a standardized blow count are presented, which
allow for hammers of varying efficiency to be accounted for. This corrected blow count is
referred to as “N60 “, because the original SPT (Mohr) hammer has about 60% efficiency, and
this is the “standard” to which other blow count values are compared. N60 is given as:
60
0.60
m B S RE C C C N
N
   

Where N60 is the SPT N-value corrected for field procedures and apparatus;
Em is the hammer efficiency;
CB is the borehole diameter correction;
CS is the sample barrel correction;
CR is the rod length correction; and
N is the raw SPT N-value recorded in the field.
Skempton (1986) provides charts for estimating the appropriate values of CB, CS and CR

Observations for Standard Penetration Test:
We perform test on the lawn outside of soil mechanics lab (UET Peshawar) where Soil is
cohesive soil.
Fall = 30 inches.
Hammer weight = 140 lb. = 63.5 kg
Drop Blows
6 inches 11 blows
12 inches 15 blows
18 inches 24 blows
Value of N = 15 blows + 24 blows = 39 blows
[We take the drop 12 inches (30cm) and 18 inches (45cm) only]
For this experiment the corrections are,
The correction factor are taken from the above table
o Hammer type is donut and mechanism is hand dropped so efficiency Em is 0.6
o Bore hole dia factor CB, As equipment variables are 65-115mm so correction factor
is 1.
o Sampler correction CS , The sample is standard so correction factor is 1
o Rod length Correction CR, As Rod length is 3-4 m so correction factor is 0.75
60
0.60
m B S RE C C C N
N
   

60
0.6 1 1 0.75 39
0.60
N
   
 = 29.25 ≈ 29
Value of N come out is 39 but after all the corrections, N60 value is 29
(Putting the values in this eq.)

Bearing Capacity of Soil:-
We can find the Bearing Capacity of Soil from SPT Number by different methods,
some of them are,
 Meyerhof’s Equations
 Bowles’ Equations
 Terzaghi’s Method (Graphical Method)
 Brinch Hansens Method
We will find the bearing capacity by the above 2 equations/methods for a footing of 4 feet
wide strip, and the bottom surface of footing is 3 feet above from ground level.
1. Meyerhof’s Equations:
Soil SPT Number, N60 = 29,
Width of footing, B = 4 feet,
Bottom surface of footing above the ground level, D = 3 feet.
Meyerhof’s Equation,
4( )N
aQ
K

1 0.33( )K D B 
Putting the values,
1 0.33(3 4)K  
K = 1.2475
29
4( )
1.2475
aQ 
Qa = 5.8 kips/ft2

2. Bowles’ Equations:
Soil SPT Number, N60 = 29,
Width of footing, B = 4 feet,
Bottom surface of footing above the ground level, D = 3 feet.
K value is same for both equations which is 1.2475 and it depends on footing type.
Bowles’ Equation,
2.5( )N
aQ
K

Where
Qa: Allowable soil bearing capacity, in kips/ft2
,
N: SPT Number below footing surface,
B: Footing Width, Measure in feet,
D = Depth from ground level to bottom surface of footing.
Putting the values in above equation.
29
2.5( )
1.2475
aQ 
Qa = 9.3 kips/ft2

Experiment # 7: “Plate Load Test”
ASTM Designation: D 1194-94
Objective:
To determine the ultimate bearing capacity using plate load test.
Need and Scope:
Plate load test is done at site to determine the ultimate bearing capacity of soil and
settlement of foundation under the loads for clayey and sandy soils. So, plate load test is helpful
for the selection and design the foundation. To calculate safe bearing capacity suitable factor
of safety is applied.
Apparatus:
 Mild Steel plate
 Reaction beam or reaction truss
 Dial gauges
 Excavating tools
 Necessary equipment for loading platform
 loading columns
 Settlement recording devices
 Hydraulic jack and pump
Test Setup for Plate Load Test

Procedure:
1. Excavate test pit up to the desired depth. The pit size should be at least 5 times the size
of the test plate (Bp).
2. At the center of the pit, a small hole or depression is created. Size of the hole is same
as the size of the steel plate. The bottom level of the hole should correspond to the level
of actual foundation. The depth of the hole is created such that the ratio of the depth to
width of the hole is equal to the ratio of the actual depth to actual width of the
foundation.
3. A mild steel plate is used as load bearing plate whose thickness should be at least 25
mm thickness and size may vary from 300 mm to 750 mm. The plate can be square or
circular. Generally, a square plate is used for square footing and a circular plate is used
for circular footing.
4. A column is placed at the center of the plate. The load is transferred to the plate through
the centrally placed column.
5. The load can be transferred to the column either by gravity loading method or by truss
method.
6. For gravity loading method a platform is constructed over the column and load is
applied to the platform by means of sandbags or any other dead loads. The hydraulic
jack is placed in between column and loading platform for the application of gradual
loading. This type of loading is called reaction loading.
7. At least two dial gauges should be placed at diagonal corners of the plate to record the
settlement. The gauges are placed on a platform so that it does not settle with the plate.
8. Apply seating load of .7 T/m2
and release before the actual loading starts.
9. The initial readings are noted.
10. The load is then applied through hydraulic jack and increased gradually. The increment
is generally one-fifth of the expected safe bearing capacity or one-tenth of the ultimate
bearing capacity or any other smaller value. The applied load is noted from pressure
gauge.
11. The settlement is observed for each increment and from dial gauge. After increasing
the load-settlement should be observed after 1, 4, 10, 20, 40 and 60 minutes and then at
hourly intervals until the rate of settlement is less than .02 mm per hour. The readings
are noted in tabular form
12. After completing of the collection of data for a particular loading, the next load
increment is applied and readings are noted under new load. This increment and data
collection is repeated until the maximum load is applied. The maximum load is
generally 1.5 times the expected ultimate load or 3 times of the expected allowable
bearing pressure.

Calculation of Bearing Capacity from Plate Load Test:
After collection of field data, the load-settlement curve is drawn. It is a logarithmic
graph where the load applied is plotted on X-axis and settlement in Y-axis. From the graph, the
ultimate load for the plate is obtained which is the corresponding load for settlement of one-
fifth of the plate width.
Bearing Capacity Calculation for Clayey Soils
Ultimate bearing capacity = ultimate load for plate
𝒒𝒖(𝒇) = 𝒒𝒖(𝒑)
Bearing Capacity Calculation for Sandy Soils
Ultimate bearing capacity = ultimate load for plate x {Width of pit (Bf) / Size of Plate (Bp)}
𝒒𝒖(𝒇) = 𝒒𝒖(𝒑) 𝒙 𝑩𝒇 / 𝑩𝒑
Finally, safe bearing capacity = ultimate bearing capacity / factor of safety
The factor of safety ranges from 2 to 3.
Calculation of Foundation Settlement from Plate Load Test:
We can also calculate settlement for given load from plate load test as follows,
Foundation Settlement Calculation on Clayey Soils
𝑆𝑒𝑡𝑡𝑙𝑒𝑚𝑒𝑛𝑡 𝑜𝑓 𝑓𝑜𝑢𝑛𝑑𝑎𝑡𝑖𝑜𝑛 (𝑠𝑓) = 𝑠𝑝 𝑥 𝐵𝑓/𝐵𝑝
Figure: Load-settlement graph
When the points are plotted on the
graph, the curve is broken at one point. The
corresponding load to that breakpoint is
considered to be the ultimate load on the
plate. The ultimate bearing capacity can be
calculated from the ultimate load from the
plate. The ultimate bearing capacity is then
divided by a suitable factor of safety to
determine the safe bearing capacity of soil
from the foundation.

Foundation Settlement Calculation on Sandy Soils
Settlement of foundation, (𝑠𝑓) = 𝑠𝑝 [{𝐵𝑓(𝐵𝑝 + 0.3)}/{𝐵𝑝(𝐵𝑓 + 0.3)}]2
Where Bf and Bp are widths of foundation and plate.
Calculations:
Size of plate = 0.305m × 0.305m
Load = 2500 KN
Max. Settlement: 25mm
Size of square c1polumn foundation =??
Observations Table:
Qo (kN)
Assume Width
Bf (m)
qo = Qo/ Bf
2
(kN/m2)
Se (P)
corresponding
to qo (mm)
Se (F) from
equation (mm)
2500 4.0 156.25 4.0 13.80
2500 3.0 277.80 8.0 26.35
2500 3.2 244.10 6.8 22.70
2500 3.1 260.10 7.2 23.86
Conclusion:
The column footing with dimensions of 3.1m × 3.1m will be appropriate

References: (ASTM)
 https://www.scribd.com/doc/226087086/ASTM-D2435-Standard-Test-Method-for-
One-Dimensional-Consolidatin-Properties-of-SoilsUsing-Incremental-Loading
 http://www.engr.mun.ca/~spkenny/Courses/Undergraduate/ENGI6723/Reading_List/
ASTM_D_4767_95_Triaxial_CU_Cohesive_Soils.pdf
 https://www.researchgate.net/publication/288191270_Standard_test_method_for_dire
ct_shear_test_of_under_drained_conditions_D3080-98
 http://www.jeanlutzsa.fr/public/temp/Normes/ASTM/D1586.17074.pdf
 https://www.scribd.com/doc/178721614/ASTM-D-1194-94-Standard-Test-Method-
for-Bearing-Capacity-of-Soil-for-Static-Load-and-Spread-Footings
 Lectures of Geotech-II lab by Engr. Zia Ullah.
THE END

Soil mechanics 2 (geotech engg) lab report

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Soil mechanics 2 (geotech engg) lab report