DARSHAN INSTITUTE OF ENGINEERING & TECHNOLOGY RAJKOT SOIL MECHANICS LAB MANUAL: 2150609 DEGREE CIVIL ENGINEERING SEMESTER: V Name of Student Roll No. Enrolment No. Class Department of Civil Engineering Geotechnical Engineering Laboratory Darshan Institute of Engineering and Technology Rajkot
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DARSHAN INSTITUTE
OF
ENGINEERING & TECHNOLOGY
RAJKOT
SOIL MECHANICS
LAB MANUAL: 2150609
DEGREE CIVIL ENGINEERING
SEMESTER: V
Name of Student
Roll No.
Enrolment No.
Class
Department of Civil Engineering
Geotechnical Engineering Laboratory
Darshan Institute of Engineering and
Technology Rajkot
2 Darshan Institute of Engineering & Technology, Rajkot
DEPARTMENT OF CIVIL ENGINEERING
2150609- SOIL MECHANICS LAB MANUAL
INDEX
Sr. No Name of Experiments Date Pg. No. Mark Sign.
SECTION 1: DETERMINATION OF COMPACTION PROPERTIES
1 Standard Proctor Test (IS : 2720 Part 7-1980)
4
2 Modified Proctor Test (IS : 2720 Part 8-1983)
4
SECTION 2: DETERMINATION OF FIELD DENSITY
3 Proctor Penetration Test 9
SECTION 3: DETERMINATION OF SHEAR PARAMETERS OF SOIL
4 Direct Shear Test (IS : 2720 Part 13-1986)
12
5 UCS Test (IS : 2720 Part 10-1973)
17
6 Vane Shear Test (IS : 2720 Part 30-1987)
22
7 Triaxial Teat (IS : 2720 Part 11-1973)
26
SECTION 4: DETERMINATION OF CONSOLIDATION PROPERTIES
8 Consolidation Test (IS : 2720 Part 15-1986)
37
SECTION 5: DETERMINATION OF SWELL PROPERTIES
9 Free Swell Index Test (IS : 2720 Part 40-1977)
47
10 Swelling Pressure Test (IS : 2720 Part 41-1987)
--
SECTION 6: DETERMINATION OF SUB GRADE STRENGTH
11 CBR Test
(IS : 2720 Part 16-1979) 50
12 Plate Bearing Test (IS : 9214-1979)
--
SECTION 7: SOIL SAMPLING
13 Augur method (Disturbed)
57
14 Hand Operating Sampler (Undisturbed)
57
3 Darshan Institute of Engineering & Technology, Rajkot
DEPARTMENT OF CIVIL ENGINEERING
2150609- SOIL MECHANICS LAB MANUAL
CONTENTS
Experiment No 1: Light & Heavy Compaction Test .................................................. 4
Experiment No 2: Direct Shear Test ...................................................................... 12
Experiment No 3: Unconfined Compressive Strength (Ucs) Test ............................ 17
Experiment No 4: Vane Shear Test........................................................................ 22
Experiment No 5: Triaxial Test .............................................................................. 26
Experiment No 6: Consolidation Test .................................................................... 37
Experiment No 8: Free Swelling Index Test ........................................................... 47
Experiment No 8: CBR Test .................................................................................. 50
Experiment No 9: Boring Methods of Exploration & Sampling............................... 57
4 Darshan Institute of Engineering & Technology, Rajkot
DEPARTMENT OF CIVIL ENGINEERING
2150609- SOIL MECHANICS LAB MANUAL
EXPERIMENT NO 1: LIGHT & HEAVY COMPACTION TEST
THEORY:
In geotechnical engineering, soil compaction is the process in which a stress
applied to a soil causes densification as air is displaced from the pores
between the soil grains. It is an instantaneous process and always takes place
in partially saturated soil (three phase system). The Proctor compaction test
is a laboratory method of experimentally determining the optimal moisture
content at which a given soil type will become most dense and achieve its
maximum dry density.
NEED & SCOPE:
Determination of the relationship between the moisture content and density
of soils compacted in a mould of a given size with a 2.5 kg rammer dropped
from a height of 31 cm. the results obtained from this test will be helpful in
increasing the bearing capacity of foundations, Decreasing the undesirable
settlement of structures, Control undesirable volume changes, Reduction in
hydraulic conductivity, Increasing the stability of slope sand so on.
APPARATUS REQUIRED:
Oven
Steel Straightedge - Mixing Tools
Trowel and spatula
Metal Rammer
Spoon
Mould: 1000 cc for light compaction in small mould and 2250 cc for heavy
compaction in large mould
Balance: 10 kg sensitive to 1 g and other of capacity 200 g sensitive to 0.01 g
Sample Extruder: (Optional)
5 Darshan Institute of Engineering & Technology, Rajkot
DEPARTMENT OF CIVIL ENGINEERING
2150609- SOIL MECHANICS LAB MANUAL
SAMPLE PREPARATION
Light compaction: Heavy compaction:
Small mould 1000cc
A representative portion of air-dried
soil material about 5 kg of material
passing a 19-mm IS Sieve shall be
taken.
Large mould 2207cc
A representative portion of air-dried
soil material about 6 kg of material
passing 40 -mm IS Sieve shall be
taken.
Small mould 1000cc
A representative portion of air-dried
soil material about 5 kg of material
passing a 19-mm IS Sieve shall be
taken.
Large mould 2207cc
A representative portion of air-dried
soil material about 30 kg of material
passing a 37.5-mm IS Sieve shall be
taken.
COMPACTION
Light Compaction: Heavy Compaction:
Small Mould:1000 cc
No of layer 3
No of blow 25
Weight of Hammer 2.6 kg
Falling height of hammer 31 cm
Large mould: 2207 cc
No of layer 3
No of blow 55
Weight of Hammer 2.6 kg
Small Mould:1000 cc
No of layer 5
No of blow 25
Weight of Hammer 4.9 kg
Falling height of hammer 45 cm
Large mould: 2207 cc
No of layer 5
No of blow 55
Weight of Hammer 4.9 kg
AMOUNT OF WATER
Clayey soil Sandy soil
Initial water :12%to 16% below
plastic limit
Water added for each stage: 2 to 4 %
Initial water :3% to 5%
Suitable
Water added for each stage: 1
to 2 %
6 Darshan Institute of Engineering & Technology, Rajkot
DEPARTMENT OF CIVIL ENGINEERING
2150609- SOIL MECHANICS LAB MANUAL
Light and Heavy compaction mould and rammer
How to Compact soil in Mould
MDD & OMC Graph and Principle of Compaction
7 Darshan Institute of Engineering & Technology, Rajkot
DEPARTMENT OF CIVIL ENGINEERING
2150609- SOIL MECHANICS LAB MANUAL
PROCEDURE:
1. Obtain a sufficient quantity of air-dried soil and pulverize it. Take about 5
kg of soil passing through 19 mm sieve in a mixing tray for light
compaction in small mould as per above table.
2. Weigh the mould with base plate and apply grease lightly on the interior
surfaces. Fit the collar and place the mould on a solid base.
3. Add initial water to the soil as per criteria given in above table then mix it
thoroughly using the trowel until the soil gets a uniform color.
4. As per guideline given in above table for light compaction in small mould
compact the moist soil in three equal layers using a rammer of mass 2.6
kg and having free fall of 31 cm.
5. Distribute the blows evenly, and apply 25 blows in each layer. Ensure that
the last compacted layer extends above the collar joint.
6. Rotate the collar so as to remove it, trim off the compacted soil flush with
the top of the mould, and weigh the mould with soil and base plate.
7. Extrude the soil from the mould and collect soil samples from the top,
middle and bottom parts for water content determination.
8. Place the soil back in the tray, add a water based on the original soil mass,
and re-mix as in step 3.
9. Repeat steps 4 and 5 and 6 until a peak value of compacted soil mass is
reached followed by a few samples of lesser compacted soil masses.
10. Calculate the bulk density of each compacted soil specimen.
11. Calculate the average moisture content of the compacted specimen and
then its dry density.
12. Plot the dry densities obtained as ordinates against the corresponding
moisture contents as abscissa, draw a smooth compaction curve passing
through them, and obtain the values of maximum dry density (MDD) and
optimum moisture content (OMC).
On the same graph, plot a curve corresponding to 100% saturation,
calculated from
8 Darshan Institute of Engineering & Technology, Rajkot
DEPARTMENT OF CIVIL ENGINEERING
2150609- SOIL MECHANICS LAB MANUAL
γd = (GS . γw ) / (1+ (wGs/ Sr))
Where,
Sr = degree of saturation,
Gs = specific gravity of solids, and
Ƴw = unit weight of water.
CALCULATIONS:
Bulk Density – γb in g/cc, of each compacted specimen shall be calculated
from the equation:
Ƴ𝑏 =𝑀2 − 𝑀1
𝑉𝑚
Where,
Ml = Empty weight of mould in gm
M2 = Mould + Wet soil in gm mass in g of mould, base and soil; and
Vm = volume of mould in cm3
The dry density, γd in g/cc, shall be calculated from the equation:
Ƴd =100Ƴ𝑏
100 + w
Where,
w = water content of soil in percent.
γb= Bulk Density g/cc
γd= Dry Density g/cc
The dry densities, 𝛄𝐝 obtained in a series of determinations shall be plotted
against the corresponding moisture contents w (%). A smooth curve shall be
9 Darshan Institute of Engineering & Technology, Rajkot
DEPARTMENT OF CIVIL ENGINEERING
2150609- SOIL MECHANICS LAB MANUAL
drawn through the resulting points and the position of the maximum on this
curve shall be determined.
REPORTING OF RESULTS:
The dry density in g/cc corresponding to the maximum point on the moisture
content/ dry density curve shall be reported as the maximum dry density to
the nearest 0.01.
FIELD CONTROL TEST- PROCTOR NEEDLE
THEORY
Field control tests may be destructive or non-destructive.
Core cutter & Sand Replacement test are destructive test and Proctor
Needles is non-destructive test.
Proctor needle test is used for quick evaluation of maximum soil density in
the field. Standard Compaction curves showing moisture contents versus
densities are drawn in laboratory using standard compaction method and
penetration of the proctor needles are correlated. Proctor needles are also
known as Proctor Penetrometers.
INSTRUMENTS
The instrument consists of a needle attached to a spring loaded plunger, the
stem of which is calibrated to read 0 to 40 kg division. Load stem is graduated
at every 12.5 mm to read depth of penetration and for use with needles of
larger areas. The small penetration stem is also graduated in 12.5 mm
division and is used with needles of smaller areas. Needle points one each of
0.25, 0.5, 1.0, 1.5, 2.0, 3.5 and 6.0 sq. cm. and one tommy pin is supplied.
The needle, fitted with a tip of knowing bearing area, is forced in to the
compacted soil in the mould in the laboratory compaction test at the rate of
1.25 cm per second to depth of 7.5 cm and penetration resistance in kg/cm2
is noted. A calibration chart is prepared by plotting the moulding water
content against penetration resistance.
10 Darshan Institute of Engineering & Technology, Rajkot
DEPARTMENT OF CIVIL ENGINEERING
2150609- SOIL MECHANICS LAB MANUAL
Proctor Needle and Penetration Resistant Curve
11 Darshan Institute of Engineering & Technology, Rajkot
DEPARTMENT OF CIVIL ENGINEERING
2150609- SOIL MECHANICS LAB MANUAL
Observation table for Determination of Water Content – Dry Density
Relation Using Light/Heavy Compaction
Type of test (Standard/ Modified proctor test)
Volume of mould (cm3) (1000cm3/2250cm3)
TEST 1 2 3 4 5
Container No.
Empty weight of container
Container + wet soil( gm)
Container+ dry soil (gm)
Mass of mould (gm)
Mass of mould + compacted soil
(gm)
Mass of compacted soil, Wt.(gm)
Bulk density (g/cc)
Needle Resistance(kg/cm2)
Average water content w (%)
Dry density (g/cc )
Dry density at 100% saturation (g/cc )
Result Summary (after plotting a graph)
Maximum Dry Density……………gm/cc
Optimum Moisture Content……………%
CONCLUSION:
12 Darshan Institute of Engineering & Technology, Rajkot
DEPARTMENT OF CIVIL ENGINEERING
2150609- SOIL MECHANICS LAB MANUAL
EXPERIMENT NO 2: DIRECT SHEAR TEST OR BOX SHEAR
TEST
THEORY & CONCEPT:
The concept of direct shear is simple and mostly recommended for granular
soils, sometimes on soils containing some cohesive soil content. The cohesive
soils have issues regarding controlling the strain rates to drained or
undrained loading.
In granular soils, loading can always assumed to be drained. A schematic
diagram of shear box shows that soil sample is placed in a square box which
is split into upper and lower halves. Lower section is fixed and upper section
is pushed or pulled horizontally relative to other section; thus forcing the soil
sample to shear/fail along the horizontal plane separating two halves. Under
a specific Normal force, the Shear force is increased from zero until the sample
is fully sheared. The relationship of Normal stress and Shear stress at failure
gives the failure envelope of the soil and provide the shear strength
parameters (cohesion and internal friction angle).
NEED & SCOPE:
The value of internal friction angle and cohesion of the soil are required for
design of many engineering problems such as foundations, retaining walls,
bridges, sheet piling.
Direct shear test can predict these parameters quickly.
APPARATUS REQUIRED:
1) Direct shear box apparatus and Loading frame (motor attached).
2) Two Dial gauges, Proving ring, Weighing Balance with accuracy of 0.01g.
3) Sample Extractor (Undisturbed sample) / Sampler for preparation of
remolded sample of dimension (60mm*60mm*25mm).
4) Tamper, Straight edge, Spatula.
5) Filter paper
6) Two porous stones
13 Darshan Institute of Engineering & Technology, Rajkot
DEPARTMENT OF CIVIL ENGINEERING
2150609- SOIL MECHANICS LAB MANUAL
7) Two corrugated metallic plates with perforation (drained) / metallic
imperforated plates with corrugation (undrained)
8) Metallic Pressure pad Balance - Balance of I kg capacity sensitive to 0.1 g.
PREPARATION OF SPECIMEN:
Undisturbed Specimens - Specimens of required size shall be prepared in
accordance with IS: 2720 (Part I)-1983.
Remoulded Specimens
a. Cohesive soils may be compacted to the required density and moisture
content (MDD & OMC), the sample extracted and then trimmed to
required size. Alternatively, the soil may be compacted to the required
density and moisture content directly into the shear box after fixing the
two halves of the shear box together by means of the fixing screws.
b. Cohesionless soils may be tamped in the shear box itself with the base
plate and grid plate or porous stone as required in place at the bottom of
the box. The cut specimen shall be weighed and trimmings obtained during
cutting shall be used to obtain the moisture content. Using this
information, the bulk dry density of the specimen in the shear box shall be
determined.
PROCEDURE:
Undrained Test -The shear box with the specimen, plain grid plate over the
base plate at the bottom of the specimen and plain grid plate at the top of the
specimen should be fitted into position in the load frame.
The grooves of the grid plates should be at right angles to the direction of
shear the loading pad should be placed on the top grid plate.
The required normal stress should be applied and the rate of longitudinal
displacement/shear stress application so adjusted that no drainage can
occur in the sample during the test.
The upper part of the shear box should be raised such that a gap of
about 1 mm is left between the two parts of the box.
14 Darshan Institute of Engineering & Technology, Rajkot
DEPARTMENT OF CIVIL ENGINEERING
2150609- SOIL MECHANICS LAB MANUAL
Accessories Placement in Shear box Application of Normal Load
Shearing of Soil in Box Direct Shear Test Instrument
Setup of Test
15 Darshan Institute of Engineering & Technology, Rajkot
DEPARTMENT OF CIVIL ENGINEERING
2150609- SOIL MECHANICS LAB MANUAL
The test may now be conducted by applying horizontal shear load to
failure or to 20 percent longitudinal displacement, whichever occurs
first.
The shear load readings indicated by the proving ring assembly and the
corresponding longitudinal displacements should be noted at regular
intervals.
CALCULATIONS AND OBSERVATION SHEET
The loads so obtained divided by the corrected cross-sectional area of the
specimen gives the shear stress in the sample. The corrected cross-sectional
area shall be calculated from the following equation:
Corrected area = Ao (1 −𝛿
3)
Where,
Ao = initial area of the specimen in cm2, and
𝛿 = displacement in cm.
16 Darshan Institute of Engineering & Technology, Rajkot
DEPARTMENT OF CIVIL ENGINEERING
2150609- SOIL MECHANICS LAB MANUAL
From the Graph;
Cohesion:
Angle of Internal Friction:
CONCLUSION
OBSERVATION SHEET
Depth- Size of box(cm)- Mass of soil (gm)-
Rate of strain - Area of box (cm2)- OMC - %
Type of test - Volume of box(cm3)- MDD - gm/cc
Least count of disp. dial gauge (mm/div.):
Proving ring constant (kg/div.):
Dial gauge reading Proving Ring
Reading
(1)
Horizontal Load
(kg)
(2)
Shear Stress
(kg/cm2)
(3)
Normal Stress
(kg/cm2)
(4)
Horizontal
Dial Gauge
Vertical
Dial Gauge
0.5
1.0
1.5
2.0
Remarks-
17 Darshan Institute of Engineering & Technology, Rajkot
DEPARTMENT OF CIVIL ENGINEERING
2150609- SOIL MECHANICS LAB MANUAL
EXPERIMENT NO 3: UNCONFINED COMPRESSIVE STRENGTH
(UCS) TEST
THEORY
Unconfined compression test also known as uniaxial compression tests, is a
special case of a triaxial test, where confining pressure is zero. UC test does
not require the sophisticated triaxial setup and is simpler and quicker test to
perform as compared to triaxial test. In this test, a cylindrical specimen of soil
without lateral support is tested to failure in simple compression, at a
constant rate of strain. Compressive load per unit area required to fail the
specimen is called unconfined compressive strength of the soil.
NEED AND SCOPE:
It is not always possible to conduct the bearing capacity test in the field.
Sometimes it is cheaper to take the undisturbed soil sample and test its
strength in the laboratory. Also to choose the best material for the
embankment, one has to conduct strength tests on the samples selected.
Under these conditions it is easy to perform the unconfined compression test
on undisturbed and remolded soil sample. Now we will investigate
experimentally the strength of a given soil sample.
APPARATUS REQUIRED:
1. Loading frame with constant rate of movement.
2. Proving ring of 0.01 kg sensitivity for soft soils; 0.05 kg for stiff soils.