Geotechnical Engineering II Experiments
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Transcript of Geotechnical Engineering II Experiments
Department : Civil EngineeringName of the Process: (Smooth and effective working of Civil
Engineering Department)
Doc. No: Ver. No;00
Issue No: 01 Date: 1 January 2010 Date: Page:1/40
Experiment No. 1
NAME OF EXPERIMENT – DIRECT SHEAR TEST1 AIM
To determine shear parameters ( c and φ ) of soil in under un-drained condition 2 APPARATUS
The shear box solid grid plates, base plates, loading pad, loading frame with slotted
weights (0.2kg/cm2, 0.5kg/cm2 1kg/cm2 and 1.5kg/cm2, proving ring of 100kg to 250kg
capacity, dial gauge 0.01 mm least count and stop clock. Loading frame 1000 kg capacity.
Balance 0.1gm mim. Capacity. Spatula and straight edge.
3 PREPARATION OF SPECIMANRemoulded SpecimensIn case of Cohesion less density moisture contents are given. Based on these values weigh
of dry soil is determined. The required moisture is added in the soil. The mould is
assembled with base plate at bottom followed by solid serration plate (perpendicular to
direction of shear force). The reference level is taken from the top of mould before samples
is poured. The soil is then tamped in the shear box itself in layers till the difference in the
layer shows 25 mm thickness of sample. The sample is then covered by solid serration
plate similar to bottom plate and finally a loading pad is placed.
4 THEORY:
This test is also called as ‘Box shear test’. The sample is subjected two dimensional
stresses such as normal stress in vertical direction and shear stress in horizontal direction
(at constant rate). The test is useful for freely drained material (sands) since pore water
pressure can not be measured. The main advantages of this test are that it is simple. The
disadvantage of the method is it can-not controlled the drainage conditions hence; it is not
suitable for fine grained soil. 5 PROCEDURE
Undrained Test – The shear box with the specimen, plain grid plate over the base plate at
the bottom of the specimen an ui7kd plain grid plate at the bottom top of the specimen is
fitted into position into load frame. 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.
The required normal stress (0.2kg/cm2, 0.5kg/cm2 1kg/cm2 in individual trial) is applied
and the rate of longitudinal displacement / shear stress application so adjusted (1.25
Prepared by Received by Approved by Issued by
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V.B. Deshmukh Geotechnical Engineering
Laboratory I/c
Dr. S.B. CharhateH.O.D.
Dr. S.D. Sawarkar Principal
Dr.H.S. ChoreM.R.
Department : Civil EngineeringName of the Process: (Smooth and effective working of Civil
Engineering Department)
Doc. No: Ver. No;00
Issue No: 01 Date: 1 January 2010 Date: Page:1/40
mm/min) that no drainage is occurred in the sample during the test.
The test is now conducted by applying horizontal shear load to failure (indicated by
decrease in proving ring reading) or to 20 percent longitudinal displacement, whichever
occurs first.
The shear load readings indicated by the proving ring assembly and the corresponding
longitudinal displacements are noted at regular intervals (say 30 units). If necessary, At the
end of the test, the specimen is removed from the box and the final moisture content is
measured.
A minimum of three (preferably four) tests shall be made on separate specimens of the
same density.
6 CALCULATIONS
Shear strain is expressed as, 100×=L
δε , Where δ is shear displacement
Shear stress is given by, A
F=τ , where F is the maximum shear force calculated from
proving ring reading.
7 RESULTSThe shear parameters in the un-drained conditions are cohesion c =
Angle of internal friction, φ =
8 DISCUSSIONS
In case of sandy soil the c is close to zero and φ value is maximum. According to
Terzaghi φ < 28 0 is classified as loose sand whereas, 380>φ > 28 0 is medium dense
sand and φ >380 is very dense sand. For saturated clays φ = 0 0.
8 PRECAUTIONSSelect the proper capacity of proving ring. In any case PRR should not exceed maximum
values given in calibration chart.No vibrations should be transmitted to the sample during the test and there should not be
any loss of shear force due to friction between the loading frame and due shear box
container assembly.The normal stresses to be selected for the test should correspond to the field conditions
and design requirements.Prepared by Received by Approved by Issued by
Compiled copy if stamp is red colour
V.B. Deshmukh Geotechnical Engineering
Laboratory I/c
Dr. S.B. CharhateH.O.D.
Dr. S.D. Sawarkar Principal
Dr.H.S. ChoreM.R.
Department : Civil EngineeringName of the Process: (Smooth and effective working of Civil
Engineering Department)
Doc. No: Ver. No;00
Issue No: 01 Date: 1 January 2010 Date: Page:1/40
DATE OF SUBMISSIONGRADESIGNATURE
Prepared by Received by Approved by Issued by
Compiled copy if stamp is red colour
V.B. Deshmukh Geotechnical Engineering
Laboratory I/c
Dr. S.B. CharhateH.O.D.
Dr. S.D. Sawarkar Principal
Dr.H.S. ChoreM.R.
Department : Civil EngineeringName of the Process: (Smooth and effective working of Civil
Engineering Department)
Doc. No: Ver. No;00
Issue No: 01 Date: 1 January 2010 Date: Page:1/40
OBSERVATIONS
DIRECT SHEAR TEST
Density, g/cc Date Moisture content Proving ring capacityDrainage condition Proving ring numberMax. Size of particle Proving ring factor C.F. Area of sample, A = 36 cm2 Dial Gauge constantLength of sample, L = 6 cmVolume, V = 90 cm3
DGR PRR Displacement mm
δ =DGR x constant
Shear strain %
100×=L
δε
Shear Force,
F= PRR x CF
Shear stress
A
F=τ kg/
cm2
0 03060Note: till PRR decreases or upto 20% strain whichever reaches earlier
Prepared by Received by Approved by Issued by
Compiled copy if stamp is red colour
V.B. Deshmukh Geotechnical Engineering
Laboratory I/c
Dr. S.B. CharhateH.O.D.
Dr. S.D. Sawarkar Principal
Dr.H.S. ChoreM.R.
Department : Civil EngineeringName of the Process: (Smooth and effective working of Civil
Engineering Department)
Doc. No: Ver. No;00
Issue No: 01 Date: 1 January 2010 Date: Page:1/40
Prepared by Received by Approved by Issued by
Compiled copy if stamp is red colour
V.B. Deshmukh Geotechnical Engineering
Laboratory I/c
Dr. S.B. CharhateH.O.D.
Dr. S.D. Sawarkar Principal
Dr.H.S. ChoreM.R.
Department : Civil EngineeringName of the Process: (Smooth and effective working of Civil
Engineering Department)
Doc. No: Ver. No;00
Issue No: 01 Date: 1 January 2010 Date: Page:1/40
Experiment No. 2
NAME OF EXPERIMENT– DETERMINATION OF UNCONFINED
COMPRESSIVE STRENGTH1 AIM : To determine Undrained Cohesion of partly saturated clayey soil2 APPARATUS
a) Split mould- Diameter 38 mm and Height 76 mm
b) Seamless tubes -38 mm diameter and 50 mm height, 3 numbers.
c) Pressure cell with central pedestal (cell pressure opening is closed)
d) Proving ring (depending on stiffness of soil)
e) Dial gauge for deformation measurement 0.01mm per unit to max. 25 mm travel
f) Loading frame of 1t capacity, arrangement for application of different strain rate
g) Solid plates with loading pad
h) Vertical sampling ejector for transferring sample from UDS tube/ compaction mould
into seamless tube.
i) Horizontal ejector for transferring sample from seamless tube to mould.
j) Miscellaneous Equipment – Specimen trimming and carving tools, water content cans,
etc, spatula, vernier caliper. Balances –weighted to the nearest 0.01 g, whereas
specimens of 100 g or larger shall be weighed to the nearest 0.1 g.
k) Oven – thermostatically controlled, with interior of non-corroding material, capable of
maintaining the temperature at 110 + 50 C.
3. PREPARATION OF TEST SPECIMENThe soil specimen to be used for test may be undisturbed, compacted or remoulded.
3.1 Specimen size – The specimen for the test shall have a minimum diameter of 38 mm and
the largest particle contained within the test specimen shall be smaller than 1/8 of the
specimen diameter. If, after completion of test on undisturbed sample, it is found that
larger particles are present than permitted for the particular specimen size tested, it shall be
noted in the repot of test data under remarks. The height to diameter ratio shall be 2.
Measurements of height and diameter shall be made with Vernier calipers or any other
suitable measuring device to the nearest 0.1 mm.3.2 Undisturbed Specimens
The undisturbed is collected in UDS tubes from the site. The wax is removed and three
seamless tubes are penetrated with help of vertical extractor. The sample is then pushed
Prepared by Received by Approved by Issued by
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V.B. Deshmukh Geotechnical Engineering
Laboratory I/c
Dr. S.B. CharhateH.O.D.
Dr. S.D. Sawarkar Principal
Dr.H.S. ChoreM.R.
Department : Civil EngineeringName of the Process: (Smooth and effective working of Civil
Engineering Department)
Doc. No: Ver. No;00
Issue No: 01 Date: 1 January 2010 Date: Page:1/40
into mould by horizontal extractor. The projected sample in the mould is then trimmed in order to make either surfaces of
sample perfectly perpendicular to axis of mould. The split mould is then opened and
sample removed by pushing solid plates on either sides of specimen.The mass and dimensions are measured and sample is assembled in the pressure cell.Representative sample cuttings shall be used for the determination of water content.
3.3 Remoulded Specimen The dry density and moisture content are given or obtained from proctor test to evaluate
dry mass of soil and moisture content. The known quantity of mixed soil sample is then
compacted into proctor mould statically or dynamically. The three seamless tubes are
pushed vertically in the mould by vertical extractor. The sample of size 38 mm diameter
and 76 mm height is obtained by pushing sample from seamless tube into mould in
horizontal extractor.
4. THEORY Unconfined compression test is a special tri-axial test. It is used when the soil to be tested
is a saturated clay and Φ = 00 condition prevails in the field. This test is similar to triaxial
compression test except cell pressure is zero. Hence, only one Mohr’s is required for
determination of ‘cu’. The figure shows Mohr’s circle and failure envelope.5. PROCEDURE
The specimen is placed on the central pedestal of cell. The top and bottom of the sample
covered with solid plate and loading pad on top solid plate. The cell cover is closed and
plunger is made in contact loading pad. The Dial (deformation) gauge and proving ring
(force measurement) are assembled on the loading frame. The deformation dial gauge and proving ring are adjusted to zero. Force shall be applied so
as to produce axial strain at a rate of 1/to 2 percent per minute. Force and deformation
readings are recorded at suitable intervals (usually 30 on dial gauge).The specimen is compressed until failure surfaces have definitely developed or the stress-
strain curve is well past or until an axial strain of 20 percent is reached.The failure pattern is sketched carefully and shown on the data sheet or on the sheet
presenting the stress-strain plot.The water content of the specimen is determined in accordance with geotechnical
engineering manual I using samples taken from the failure zone of the specimen.
6. CALCULATIONSStress-Strain values shall be calculated a follows:
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V.B. Deshmukh Geotechnical Engineering
Laboratory I/c
Dr. S.B. CharhateH.O.D.
Dr. S.D. Sawarkar Principal
Dr.H.S. ChoreM.R.
Department : Civil EngineeringName of the Process: (Smooth and effective working of Civil
Engineering Department)
Doc. No: Ver. No;00
Issue No: 01 Date: 1 January 2010 Date: Page:1/40
a) The axial strain, ε %, is determined is expressed as
1000
×∆=L
Lε
Where,
L = the change in the specimen length as read from the strain dial indicator, and
L0 = the initial length of the specimen.
b) The average cross-sectional area, A, at a particular strain shall be determined from the
following relationship:
0
1L
L
AA o
∆−=
Where,
A0 = the initial average cross-sectional area of the specimen
c) Compressive stress, σ c, shall be determined from the relationship
A
Pc =σ
Where,
P is the compressive force kg, and A = average cross-sectional area, cm2 Values of stress σ c, and strain, ε %, obtained from above calculations are plotted on
abscissa and ordinate respectively. The maximum stress from this plot gives the value of
the unconfined compressive strength, qu.
7. RESULTSThe unconfined compression strength qu
The un-drained cohesion cu
8 DISCUSSIONThe failure plane α is 450 if φ = 00 for fully saturated clay sample otherwise it is partly
saturated or particles oversize 2mm. 9 Proving ring reading and dial gauge reading are recorded within their limits as referred
from calibration chart.The selection of capacity of proving ring depends on stiffness of sample. The basic
physical properties also indicated the approximate strength.During the preparation and assembling of the sample a care must taken reduce the
Prepared by Received by Approved by Issued by
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V.B. Deshmukh Geotechnical Engineering
Laboratory I/c
Dr. S.B. CharhateH.O.D.
Dr. S.D. Sawarkar Principal
Dr.H.S. ChoreM.R.
Department : Civil EngineeringName of the Process: (Smooth and effective working of Civil
Engineering Department)
Doc. No: Ver. No;00
Issue No: 01 Date: 1 January 2010 Date: Page:1/40
disturbances.DATE OF SUBMISSIONGRADESIGNATURE
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V.B. Deshmukh Geotechnical Engineering
Laboratory I/c
Dr. S.B. CharhateH.O.D.
Dr. S.D. Sawarkar Principal
Dr.H.S. ChoreM.R.
Department : Civil EngineeringName of the Process: (Smooth and effective working of Civil
Engineering Department)
Doc. No: Ver. No;00
Issue No: 01 Date: 1 January 2010 Date: Page:1/40
OBSERVATION TABLE
UNCONFINED COMPRESSION TEST
1. Details of the soil specimen:
i. Undisturbed or remoulded or compacted:
ii. Initial diameter, D0 mm
iii. Initial length, Lo mm
iv. Initial area, A0 cm2
v. Initial mass of the specimen g
vi. Initial density g/cm2
vii. Initial water content %
2. Proving Ring No.
3. Proving ring capacity
4. Proving ring factor, C
5. Dial Gauge Constant ,G
DGR PRR Compressive
Force in kg
PRR x CF
Deformation
ΔL = DGR x G
mm
Strain in
%
100ΔL/L0
Area A in
cm2
Compressive Stress
qu in kg/cm2
(1) (2) (3) (4) (5) (6) (7)03060
Note: Test is continued till PRR decreases or 20% whichever earlier
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V.B. Deshmukh Geotechnical Engineering
Laboratory I/c
Dr. S.B. CharhateH.O.D.
Dr. S.D. Sawarkar Principal
Dr.H.S. ChoreM.R.
Department : Civil EngineeringName of the Process: (Smooth and effective working of Civil
Engineering Department)
Doc. No: Ver. No;00
Issue No: 01 Date: 1 January 2010 Date: Page:1/40
Figure Schematic diagram showing sample in unconfined compression test
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V.B. Deshmukh Geotechnical Engineering
Laboratory I/c
Dr. S.B. CharhateH.O.D.
Dr. S.D. Sawarkar Principal
Dr.H.S. ChoreM.R.
Department : Civil EngineeringName of the Process: (Smooth and effective working of Civil
Engineering Department)
Doc. No: Ver. No;00
Issue No: 01 Date: 1 January 2010 Date: Page:1/40
Experiment No. 3
1 NAME OF EXPERIMENT – TRI-AXIAL COMPRESSION TEST2 AIM – Determination of the shear strength parameters of a partly saturated sample in
Unconsolidated Undrained Triaxial Compression without the measurement of pore water
Pressure. IS: is referred for the procedure.3 APPARATUS
Split Mould – 36 mm diameter and length 72 mm.Trimming knife – sharp-bladed, for example, a spatula or pallet knife.Metal StraightedgeMetal ScaleNon-Corrodible Plastic End-Caps – of the same material as the test specimen. The upper end
cap is to have a central spherical seating to receive the loading ram (see Note).Note: A solid plastic end cap, 20 mm thick, is normally satisfactory for use on soft or very soft soils.
Seamless tubes – in the form of a steel tube, open at both ends of internal diameter 36mm and
of length 50 mm.
The Rubber Membrane- the thickness should be selected having regard to the size, strength
and nature of the soil to be tested. A thickness of 0.2 to 0.3 mm is normally satisfactory.Membrane Stretcher – steel tube 38 mm diameter with rubber tube in the middle to for suction.Rubber Rings – of circular cross-section stretchable to suit the 36 mm diameter of the end
caps.Apparatus for Moisture content Determination – as described in Geotechnical engineering I
manual.Balance – readable and accurate to 0.1gVertical Extruders - to transfer sample from UDS tubes / compaction mould into seamless
tubes.Horizontal Extruder- It is a table mounted arrangement to push the sample from seamless tubes
into split mould.
Triaxial Test Cell – A transparent chamber to withstand the maximum pressure of 10 kg/cm2
and provided with a plunger for applying additional axial compressive load to the specimen by
means of a loading ram. is recommended. The base of the cell is provided with a suitable
central pedestal with drainage outlets with valves.Cylinder with pressure gauge for applying and maintaining the desired pressure on the Fluid
within the Cell – to an accuracy of 0.1 kg/cm2 with a gauge for measuring the pressure. The
cylinder is filled with 2/3 of volume by water.Loading frame - For Applying Axial Compression to the Specimen – 1 t loading capacity
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V.B. Deshmukh Geotechnical Engineering
Laboratory I/c
Dr. S.B. CharhateH.O.D.
Dr. S.D. Sawarkar Principal
Dr.H.S. ChoreM.R.
Department : Civil EngineeringName of the Process: (Smooth and effective working of Civil
Engineering Department)
Doc. No: Ver. No;00
Issue No: 01 Date: 1 January 2010 Date: Page:1/40
and operate at convenient speeds to convert the range 0.05 to .5 mm per minute. Proving ring- 100 kg capacity with sensitivity of 0.2 kg for low strength soils and one of 1000
kg capacity with sensitivity of 1 kg for high strength soils.
Dial Gauge – 0.01 mm least count with provision for maximum compression of 25 mm is
used.4. PREPARATION OF SPECIMENS4.1 Undisturbed Specimens
The object of specimen preparation is to produce cylindrical specimens of height twice the
specimen diameter with a plane ends normal to the axis and with the minimum change of the
soils structure and moisture content.
A specimen from a sampling tube of the same internal diameter as the required specimen may
be obtained as given in (a) to (e).
a) A UDS sample is cut from the site with and sealed with wax on either sides
b) The wax, used for sealing, is removed and the cutting edge end of the sample smoothed so
that it is approximately normal to the axis of the tube. Three seamless tubes are pushed
vertically into UDS tube which is held in vertical extruder. All seamless tubes are cut from
the UDS sample by rotating and lifting vertically.
c) The horizontal extruder is then used to push the each sample through the seamless tube
into split mould. The sample is leveled and then removed by opening split moulds.
d) The length, diameter and weight of the specimen is measured to an accuracy enabling the
bulk density to be calculated to an accuracy of + 1.0 percent.
e) The specimen is placed on one of the end caps and the other end cap is put on top of the
specimen. The rubber membrane shall then be placed around the specimen using the
membrane stretcher and the membrane sealed to the end caps by means of rubber rings.
f) The specimen is then ready to be placed on the pedestal in the Triaxial cell. The pedestal
covered with a solid end cap or the drainage valve is kept closed.4.2 Remoulded Samples
a) The dry weight of soil and quantity of water are calculated from the given density and
moisture. The soil mixed with moisture contained is then compacted in compaction mould by
dynamic or static method. The sample is then cut in three seamless tubes using vertical
extractor and finally pushed into mould by horizontal extractor. Follow the procedure in (c-f).5 THEORY
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V.B. Deshmukh Geotechnical Engineering
Laboratory I/c
Dr. S.B. CharhateH.O.D.
Dr. S.D. Sawarkar Principal
Dr.H.S. ChoreM.R.
Department : Civil EngineeringName of the Process: (Smooth and effective working of Civil
Engineering Department)
Doc. No: Ver. No;00
Issue No: 01 Date: 1 January 2010 Date: Page:1/40
Tri-axial test overcomes demerits of box shear test. It is more advantageous due measurement
of volume change during test and state of stress at any time during testing.Unconsolidated Undrained test is performed immediately the applying the confining pressure.
The failure loading is applied to the sample so rapidly that no pore water pressure can drain or
escape from the specimen during the test. The test will be always produce a value of φ of 00
for saturated cohesive soils, this is often describe as φ = 00 condition.
The choice of drainage condition depends on drainage condition expected in the site. If the soil
is sandy, excess pore pressure resulting from the new load usually expected to dissipete rapidly
and drained condition should be expected. If the soil is stressed in the field is saturated clay,
excess pore pressure dissipates slowly and φ = 00 condition governs: thus a UU test is the
proper choice.
The UU test is often called a ‘quick ‘test (Q test) because it can be performed quickly
compared to the other two types of loading and drainage tests. It is usually completed in 30
minutes per specimen. 6. TESTING PROCEDURE
The specimen prepared as described above is placed centrally on the solid circular plate in top
and bottom which is finally rest on the pedestal of the Triaxial cell. The cell is assembled with
the loading ram resting on solid plate and load pad.
The cell containing the specimen is placed in the loading machine. The operation fluid is
admitted to the cell from cylinder and the pressure is raised to the desired value.The proving ring and dial gauges are installed at their appropriate locations. The loading
machine is then further adjusted to bring the loading ram just in contact with the seat on the
top cap of the specimen and the initial reading of the gauge measuring the axial compression
of the specimen shall be recorded.
A rate of axial compression is selected (Gear No.1) such that failure is produced within a
period of approximately 5 to 15 minutes. The test commenced with a sufficient number of
simultaneous readings of the proving ring and dial gauge are taken to define the deviator
stress-axial strain curve.
The test is continued until the maximum value of the stress has been passed or until an axial
strain of 20 percent has been reached. Note: - It is often convenient to make a plot of load versus compression as the test proceeds, to
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V.B. Deshmukh Geotechnical Engineering
Laboratory I/c
Dr. S.B. CharhateH.O.D.
Dr. S.D. Sawarkar Principal
Dr.H.S. ChoreM.R.
Department : Civil EngineeringName of the Process: (Smooth and effective working of Civil
Engineering Department)
Doc. No: Ver. No;00
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enable the point of failure to be determined.The cell is drained of fluid, dismantled and the specimen taken out. The rubber membrane is
removed from the specimen and the mode of failure shall be noted (see Note 1).
The specimen is weighed (see Note 2) and samples for the determination of the moisture
content of the specimen is taken [see Geotechnical Engineering Manual I]. If there is a
moisture change in the specimen, it should be recorded and discretion used with regard to
acceptability of the test.
Note 1: - The most convenient method of recording the mode of failure is by means of a sketch
indicating the position of the failure planes. The angle of the failure plane (s) to the horizontal
may be recorded, if required. These records should be completed without undue delay to avoid
loss of moisture from the specimen.Minimum three samples are tested at higher cell pressure (usually twice the earlier pressure).Note 2 – Comparison with the recorded weight of the specimen before testing provides a check
on the impermeability of the rubber membrane if water has been used as the operating fluid in
the cell.
7. CALCULATIONSStress-Strain values shall be calculated a follows:
d) The axial strain, ε %, is determined is expressed as
1000
×∆=L
Lε
Where,
L = the change in the specimen length as read from the strain dial indicator, and
L0 = the initial length of the specimen.
e) The average cross-sectional area, A, at a particular strain shall be determined from the
following relationship:
0
1L
L
AA o
∆−=
Where,
A0 = the initial average cross-sectional area of the specimen
f) Deviator stress, σ d, is determined from the relationship
Prepared by Received by Approved by Issued by
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V.B. Deshmukh Geotechnical Engineering
Laboratory I/c
Dr. S.B. CharhateH.O.D.
Dr. S.D. Sawarkar Principal
Dr.H.S. ChoreM.R.
Department : Civil EngineeringName of the Process: (Smooth and effective working of Civil
Engineering Department)
Doc. No: Ver. No;00
Issue No: 01 Date: 1 January 2010 Date: Page:1/40
A
Wdd =σ
Where,
Wd is the compressive force kg, and A = average cross-sectional area, cm2
g) The major principal stress is expressed as, σ 1 =σ d +σ 3 where, σ 3 is minor cell pressure.8. RESULTS
The undrained cohesion cu =
Angle of Internal Friction φ = 9 PRECAUTION
Proving ring reading and dial gauge reading are recorded within their limits as referred from
calibration chart.The elastic membrane must dry and dusted in power in order to reduce the friction.The selection of capacity of proving ring) depends on stiffness of sample. The basic physical
properties also indicated the approximate strength.During the preparation and assembling of the sample a care must taken reduce the
disturbances.DATE OF SUBMISSIONGRADESIGNAURE
Prepared by Received by Approved by Issued by
Compiled copy if stamp is red colour
V.B. Deshmukh Geotechnical Engineering
Laboratory I/c
Dr. S.B. CharhateH.O.D.
Dr. S.D. Sawarkar Principal
Dr.H.S. ChoreM.R.
Department : Civil EngineeringName of the Process: (Smooth and effective working of Civil
Engineering Department)
Doc. No: Ver. No;00
Issue No: 01 Date: 1 January 2010 Date: Page:1/40
OBSERVATIONS
TRIAXIAL COMPRESSION TEST
Specimen preparation procedure Bulk Density,g/cm3
Initial length of specimen, L NMC
Initial diameter of sample, d
Initial Area of sample, Ao Rate of strain
Initial weight of specimen Dial gauge least count ‘C’
Proving ring No. Sketch of specimen after failure
Proving ring capacity
Mode of failure
Angle of failure plane with vertical
Cell pressure σ3 = .. kg/ cm2
Dial
gauge
Reading
(DGR)
Proving
Ring
Reading
(PRR)
δl = DGR x
C
Strain %
100×=L
lδε
Deviator
Load
Wd =
PRR*CF
Corrected Area
1001
0 ×−
=
L
l
AA f δ
Deviator
Stress,
kg/cm2
fd A
Wdσ
Note: CF = Refer calibration chart
From the stress-strain curves principle stresses are evaluated as
Sample No. 1 2 3Maximum deviator stress, σ dmax kg/cm2
Cell pressure σ 3, kg/cm2
Major principal stress, σ 1,= σ 3,+ σ dmax
kg/cm2
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V.B. Deshmukh Geotechnical Engineering
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Dr. S.B. CharhateH.O.D.
Dr. S.D. Sawarkar Principal
Dr.H.S. ChoreM.R.
Department : Civil EngineeringName of the Process: (Smooth and effective working of Civil
Engineering Department)
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Experiment No 4
NAME OF EXPERIMENT –CONSOLIDATION TEST1 AIM
To determine the compressibility parameters i.e. coefficient of consolidation (cv) , coefficient
of compressibility (av) , compression index (cc) , coefficient of volume change (mv) and
preconsolidation pressure (pc).2. APPARATUS2.1 Consolidating Ring
The diameter of ring 60 mm and 20 mm thick. The ring is rigid and made of a material
which is non-corrosive. The inner surface is smooth and highly polished.The ring shall be provided with a cutting edge in order to facilitate preparation of specimens.The height of the ring shall not be less than 20mm with a diameter to height ratio of about
3.0 and further the specimen height shall be not less than 10 times the maximum particle
size.2.2 Porous Stones
These stones are placed at the top and bottom of the soil specimen, and shall be of silicon
carbide, aluminum oxide or other porous materials not attacked by the soil. The porosity of
the stones are such that free drainage is assured throughout the test, but that no intrusion of
soil into the pores of the stones takes place.
A sheet of Whatman No. 54 filter paper of diameter equal to that of the stone, may be placed
between the stone and the soil surface in order to prevent intrusion.2.3 Consolidation Cell – A container within which is placed the consolidation ring containing
the specimen between the top and bottom porous stones. The cell is capable of being filled
with water to a level higher an axial vertical load applied to the top of the specimen and of
allowing measurement of the change in height of the specimen on its central axis.2.4 Dial Gauge – The gauge that read to an accuracy of at least 0.01 percent of the specimen
height and have a travel of at least 50 percent of the specimen height. 2.5 Loading Device
A device which enables vertical force to be applied axially in suitable increments, to the test
specimen, through a suitable loading yoke. The force is applied to the loading cap of the specimen centrally through some form of
spherical seating. The applied load is known to an accuracy of at least + 1percent. The loading device permits application of a load increment within a period of 2 s without
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significant impact.Trimming Equipment – Metal straightedge, thin bladed trimming knife (like spatula).Equipment for Measuring Initial Height of Test Specimen to Accuracy of 0.1 mm – Vernier
reading calipers.Moisture Content Containers and Drying Air-Oven Maintained at 110 + 50C, Desiccator.Balance Sensitive to 0.01 g – For weighing the specimen and moisture content.Stop watch readable to 1 s.
3. THEORY
Every structure resting on soil settles therefore, compressibility is the important physical
property. It is the dependent properties. Compressibility of soil is related to magnitude of
settlement and time of settlement. The experimental determination is based on one
dimensional consolidation that takes place along vertical direction of saturated compressible
soil. The coefficient compressibility Cv indicates the time required for settlement of
foundation. The compression index Cc, coefficient of volume change mv, determines the
magnitude of settlement. The types of clay deposits depends on the magnitude of
preconsolidation pressure pc whereas 1-Dimensional consolidation is is similar to
permeability hence, an approximate value of coefficient of permeability is also determined.
The Darcy’s law is valid and sample is fully saturated before it is consolidated. This test
consolidates the undisturbed soil but can be extended to compacted soil.
4.
4.1
PROCEDURE
Preparation of Test Specimen Determine the weigh the empty consolidation ring (W1).If the specimen is prepared from a UDS sample, a representative sample for testing is
extruded and cut off, care is taken to ensure that the two plane faces of the resulting soil disc
are parallel to each other. The thickness of the disc of soil shall be somewhat greater than the
height of the consolidation ring.The consolidation ring with cutting edge is gradually inserted into the sample by pressing
with hands and carefully removing the material and the ring. The consolidation ring is
sometimes pushes along with a guide ring placed on the top. The surrounding of sample is
loosened by spatula and entire assembly is cut at bottom. The soil sample thus obtained is trimmed flush with the top and bottom edges of the ring.
For soft to medium soils, excess soil should be removed using a wire saw and final trimming
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may be done with a straight edge, if necessary. For stiff soils, a straight edge alone is used
for trimming. Excessive remoulding of the soil surface by the straight edge should be
avoided. In the case of very soft soils, special care should be taken so that the specimen may
not fall out of, or slide inside the ring during trimming.A sample of soil similar to that in the ring. Taken from the trimming, is used for determining
moisture content.The thickness of the specimen (H0) shall be measured and weighed immediately (W2).
4.2 Assembly of ApparatusThe bottom porous stone are centered on the base of the consolidation cell When testing
softer, normally consolidated clays, the porous stones are made wet and covered by a wet
filter paperThe ring and specimen are placed centrally on the bottom porous stone and the upper porous
stone, and then the loading cap are placed on top. A small water chamber with head of water
equaled to mid height of sample is connected at the bottom of consolidometer. In new type
of consolidometer spce between the cell and outside boundary is filled with water.The consolidometer is placed in position in the loading device and suitably adjusted. The dial
gauge is then clamped into position for recording the relative movement between the base of
the consolidation cell and the loading cap. A seating pressure of 0.05 kgf/cm2 is applied to
the specimen.The specimen shall then be allowed to reach equilibrium for 24 h.
4.3 LoadingFor consolidation testing, it is generally desirable that the applied pressure at any loading
stage be double than at the preceding stage. The test may therefore be continued using a
loading sequence which would successively apply stress of 0.1, 0.2, 0.4, 0.8, 1.6, 3.2 and 6.4
kgf/cm2, etc, on the soil specimen.For each loading increment, after application of load, readings of the dial gauge are taken
using a time sequence such a 0, 0.25, 1, 2.25, 4, 6.25, 9, 12.25, 16, 20.25, 25, 36, 49, 64, 81,
100, 121, 144, 169, 196, 225, min, etc, up to 24 h or 0, ¼, ½, 1, 2, 4, 8, 15, 30 and 60 min,
and 2,4,8 and 24 h. These time sequences facilitate plotting of thickness or change of
thickness of specimen against square root of time or against log time.
The loading increment is left at least until the slope of the characteristic linear secondary
compression portion of the thickness versus log time plot is apparent, or until the end of
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be sufficient, but longer times may be required. If 24 h are seen to be sufficient, it is
recommended that this commonly used load period be used for all load increments. In every
case, the same load increment duration is used for all load increments during a consolidation
test.It is desirable that the final pressure be of the order of at least four times the pre-
consolidation pressure, and be greater than the maximum effective vertical pressure which
will occur in-situ due to overburden and the proposed construction.On completion of the final loading stage, the specimen is unloaded by pressure decrements
which decrease the load to ¼ of the last load. Dial gauge readings are taken as necessary to
proceed much more rapidly (after every 2 hours.)On completion of this decrement, the water shall be siphoned out of the cell and the
consolidometer is quickly dismantled after release of the final load. The specimen,
preferably within the ring, is wiped free of water, weighed (W3) and thereafter placed in the
oven for drying. If the ring is required for further testing, the specimen may be carefully
removed from the ring in order to prevent loss of soil, and then weighed and dried.Following drying, the specimen with ring is reweighed (W4).The specific gravity of the sample is determined at the end.
5. CALCULATIONS5.1 Coefficient of consolidation, cv
The coefficient of consolidation, cv, for the load increment under consideration may be
calculated from the formula:
( )90
2848.0
t
HC av
v =
Where,
Hav is the average specimen thickness for the load increment
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5.2
5.3
Relation between void ratio e and effective σ pressure
Methods
i) Change in void ratio method and
ii) Equivalent height of solid method
In change in void ratio method
Change in height after every increment of effective pressure H is given as
HHH ∆−= 0
Whereas, ΔH mm= (Final DGR-Initial DGR) and Ho is the original height of sample
Final void ratio, ef is given by
Gwe ff =
Where, wf is the final moisture content at the end of consolidation
Change in void ratio Δe is given as
( )H
H
ee
f
f ∆+
=∆1
The coefficient of compressibility, av
From the plot of the void ratio, e versus σ , the slope of the straight line portion that is for
the soil in the normally consolidated state is designated as Coefficient of compressibility, av
cm2/kg is given by
σ∆∆= e
av
5.4 Compression Index, Cc
From the plot of the void ratio, e versus log σ . The slope of the straight line portion that is
for the soil in the normally consolidated state is designated as Cc. This can be directly
obtained from the plot or calculated as:
∆=
1
2logσσe
Cc
5.5 Coefficient of volume change
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σ∆+= e
mv
1
5.6 Coefficient of Permeability K
wvv mck γ=5.7 Coefficient of Permeability K
wvv mck γ=
6. RESULTS Applied pressurecoefficient of consolidation, cv
coefficient of compressibility av
compression index cc
coefficient of volume change mv
preconsolidation pressure pc
Approx. coefficient of permeability, k
Initial void ratio, e7 DISCUSSIONS
The pressure increment (effective stress) depends on actual effective overburden stress at
site. The increment varies from 60% to 200% of that effective overburden pressure. In case
of stiff clay pressure increment may be may starts from 0.2 kg/cm2 to 8 kg/cm2 but in no case
it exceeds ultimate bearing capacity.8 PRECAUTIONS
The porous stones used for drainage should be saturated for 48 hrs and boiled for at least half
an hour before used in the test.
The use of oil is strictly not recommended during the cutting and leveling of the sample.
The sample preparation is skilled process at least disturbances are allowed during the
preparation.
The spatula used in cutting / leveling the sample must be wet each time before touch to the
sample.
The set up should be free from any shocks, vibrations and direct access to outsiders.DATE OF SUBMISSIONGRADESIGNAURE
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s a m p le
D ia l G a u g e
P o r o u s S t o n e s
S a tu r a t i o n t a n k
Figure : Cross-section of Odometer
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OBSERVATIONS
CONSOLIDATION TEST
Project ………………………………… Specimen measurements Water contentSample No. …………………………… Diameter D =……………… cm Can no. = …………………………Soil Identification ………………………. Area A = π D2/4 ………….. cm2 Wt. of can + wet soil = ………… gSpecific gravity …………………………. Thickness H0 = ……………. Cm Wt. of can + dry soil = ………… gSpecimen preparation ………………… Wt. of ring (W1) = …………… g Wt. of can = …………………….g Procedure ……………………………… Wt. of specimen + ring (W2) = …….. g Wt. of water = …………............. gType of water used …………………… Final wt. of specimen (W3) = ………. Wt. of dry soil = ……………….. g
Dry wt. of specimen + ring (W4) …….. g Water content, percent = …………Density = ……….. g/cm3
Consolidation test: pressure increment data
Date Time
elapsed,
min
Dial Gauge Reading DGR Remarks
Loading Unloading0.1kg/
cm2
0.2
kg/cm2
0.4
kg/cm2
0.8
kg/cm2
1.6
kg/cm2
3.2
kg/cm2
6.4
kg/cm2
6.4kg/cm2 Unloading
readingsAre
1.6kg/cm2 recordedevery two
0.4kg/cm2 hrs
0.1kg/cm2
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Relation between void ratio e and effective σ pressure
Hf = Gwe ff = ( )
HH
ee
f
f ∆+
=∆1
Applied
Pressure
(kgf/cm2)
σ
Final Dial
Reading
Compression
H (mm)= Diff.
in successive final
DGR
Specimen height
H (cm)= H0 -H
e Void
Ratio
e
Remarks
(1) (2) (3) (4) (5) (6) (7)
Last reading Hf =
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Experiment No 5
NAME OF EXPERIMENT : VANE SHEAR TESTS1 AIM
To determine shear strength of saturated clay with referenced to IS 2720 Part (30)1980
2. APPARATUS2.1 Vane – The vane consist of four blades each fixed at 900 to the adjacent blades as
illustrated. It should not deform under the maximum torque for which it is designed. The
penetrating edges of vane blades are sharpened having an included angle of 900. The vane
blades are welded together suitably to a central rod, the maximum diameter of which
should preferably not exceed 2.5 mm in the portion of the rod which goes into the specimen
during the test. The vane is properly treated to prevent rusting and corrosion.
2.2 The frame: The apparatus maybe either of the hand-operated type or motorized. Provisions
should be made in the apparatus for the following:
a) Fixing of vane and shaft to the apparatus in such a way that the vane can be lowered
gradually and vertically into the soil specimen.
b) Fixing the tube containing the soil specimen to the base of the equipment for which it
should have suitable hole.
c) Arrangement for lowering the vane into the soil specimen (contained in the mould fixed
to the base) gradually and vertically, and for holding the vane properly and securely in
the lowered position.
d) Arrangement for rotating the vane steadily at a rate of approximately 1/60 rev/min
(0.10/s) and for measuring the rotation of the vane.
e) A torque applicator to rotate the vane in the soil and a device for measuring the torque
applied to an accuracy of 0.05 cm. kgf.A typical form of the hand/motorized apparatus is shown in Figure.
Graduated circle calibrated 0-3600
Mould : Diameter 30 mm and Height 70 mm
Spring: Stiffness varying from 2kg/cm2 to 8kg/cm2
3. THEORY
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Laboratory vane shear test is used for soft saturated clayey (cu= 12.5 kN/m2) soil which is
difficult to withstand the self weight. This is kind of test where failure of sample is due
to torque application.
4. PROCEDURE
The specimen in the tube should be at least 30 mm in diameter and 75 mm long. If the
specimen container is closed at one end, it should be provided at the bottom with a hole of
about 1 mm diameter. Cut the undisturbed specimen and find out the density and small
sample for NMC.
Mount the specimen container with specimen on the base of the vane shear apparatus and
fix it securely to the base. Lower the shear vanes into the specimen to their full length
gradually with minimum disturbance of the soil specimen so that the top of the vane is at
least 10 mm below the top of specimen. Note the readings of the strain and torque
indicators. Rotate the vane at a uniform rate approximately 0.10/s by suitably operating the
torque applicator handle until the specimen fails. Note the final reading of the torque
indicator. Torque readings and the corresponding strain reading may also be noted at
desired intervals of time as the test proceeds.Just after the determination of the maximum torque, rotate the vane rapidly through a
minimum of ten revolutions. The remoulded strength is then be determined within 1 minute
after completion of the revolution.
5. CALCULATIONS
Un-drained shear strength kg/cm2
+
=
622 dH
d
TS u
π
Where,
T is the torque kg-cm
d is the diameter of vane in cm
H is the height of vane in cm
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Sensitivity ( )( ) remouldedS
dundistrubeS
u
u=
6
7
8
RESULTS
The undrained shear strength of clay is evaluated as
Sensitivity
DISCUSSIONS
The cu determined from above results shows …..clay. The sensitivity for marine clay
obtained from Thane creek shows 5-12.
PRECAUTIONS
It is important that the dimensions of the vane are checked periodically to ensure that the
vane is not distorted or worn out.
DATE OF SUBMISSION
GRADE
SIGNAURE
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Figure : Typical hand/motorized vane shear apparatus
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Figure: Details of vanes attached to vane rod
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OBSERVATIONS
VANE SHEAR TEST
Bulk Density, kg/cm2
NMC
Diameter of Vane, D
Height of Vane, H
Spring Factor, K kg-cm
A) Undisturbed Shear Strength
Sr. No. Initial Reading
degree
Final
Reading
degree
Difference
in radians
Torque T
=Difference x K
Shear
Strength Su
kg/cm2
12 Average undisturbed shear strength Su kg/cm2
B) Remoulded Shear Strength
Sr. No. Initial Reading
degree
Final
Reading
degree
Difference
in radians
Torque T
=Difference x K
Shear
Strength Su
kg/cm2
12 Average disturbed shear strength Su kg/cm2
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Experiment No. 6
NAME OF EXPERIMENT- CALIFORNIA BEARING RATIO TEST
1 AIM
Laboratory determination of California Bearing Ratio at un-soaked condition.
2 APPARATUSMoulds with Base Plate: 150 mm diameter and 175 mm in height and base plate of 235
mm diameter.
Stay Rod and Wing Nut - Spacer Disc, Metal Rammer, WeightsLoading Machine - With a capacity of at least 5 000 kg and equipped with a movable
head or base which enables the plunger to penetrate into the specimen at a deformation
rate of 1.25 mm/min- The machine is equipped with a load device that can read to
suitable accuracy.Penetration Plunger: 50 mm diameter and height of 50 mm with hole for connectionDial Gauges - Two dial gauges reading to 0.01 mm least countSieves – 4.75 mm and 19 mm IS sievesMiscellaneous Apparatus - Other general apparatus, such as a mixing bowl, straightedge,
scales, soaking tank or pan, drying oven, filter paper, dishes and calibrated measuring jar.Surcharge weights – 2.5 kg annular weights of two numbers
3 PREPARATION OF SPECIMEN
The dry density for a remoulding is either the field density or the value of the maximum
dry density estimated by the compaction tests or any other density at which the bearing
ratio is desired.
The water content used for compaction is the optimum water content or the field
moisture as the case may be.
Soil Sample - The material used in the remoulded specimen passes a 19-mm IS Sieve.
Allowance for larger material is made by replacing it by an equal amount of material
which passes a 19-mm IS sieve but is retained on 4’75-mm IS Sieve.
Statically Compacted Specimens - The mass of the wet soil at the required moisture
content to give the desired density when occupying the standard specimen volume in the
mould shall be calculated. A batch of soil shall be thoroughly mixed with water to gives
the required water content. The correct mass of the moist soils is placed in the mould and
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compaction obtained by pressing in the displacer disc, a filter paper being placed
between the disc and the soil.
Dynamically Compacted Specimen - For dynamic compaction, a representative sample
of the soil weighing approximately 4.5 kg or more for fine-grained soils and 5.5 kg or
more for granular soils is taken and mixed thoroughly with water. If the soil is
compacted to the maximum dry density at the optimum water content the exacta mass of
soil required is taken and the necessary quantity of water added so that the water content
of the soil sample is equal to the determined optimum water content. The mould with the
extension collar attached shall be clamped to the base plate. The spacer disc shall be
inserted over the base plate and a disc of coarse filter paper placed on the top of the
spacer disc. The soil-water mixture shall be compacted into the mould.
The extension collar is then removed and the compacted soil carefully trimmed even with
the top of the mould by means of a straightedge. Any hole that may then, develop on the
surface of the compacted soil by the removal of coarse material, is patched with smaller
size material; the perforated base plate and the spacer disc are removed, and the mass of
the mould and the compacted soil specimen recorded. A disc of coarse filter paper shall
be placed on the perforated base plate, the mould and the compacted soil is inverted and
the perforated base plate clamped to the mould with the compacted soil in contact with
the filter paper.
4 THEORY
The potential soil subgrade is assessed by CBR method. It is used for design of thickness
of pavement. Lower the CBR value indicates poor subgrade and hence, higher the
thickness required. The CBR value of a soil is considered to be an index which in some
fashion is related to its strength. The value is highly dependent on the condition of the
material at the time of testing. Recently, attempts have been made to correlate CBR
values to parameters like modulus of subgrade reaction, modulus of resilience and
plasticity index, with considerable success.
The load settlement curve (standard curve) for perfectly contacted plunger and error
curve (modified curve) are shown in following figure.
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The standard load at various penetration are given as
Penetration mm Standard load, kg Standard pressure kg/cm2
2.5 1370 705 2055 105
5 PROCEDURE
Penetration Test (see Figure) - The mould containing the specimen, with the base plate in
position but the top face exposed, is placed on the lower plate of the testing machine.
Surcharge weights, sufficient to produce an intensity of loading equal to the weight of
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the base material and pavement are placed on the specimen.
The plunger is seated under a load of 4 kg so that full contact is established between the
surface of the specimen and the plunger.
The load and deformation gauges are then be set to zero. Load is applied to the plunger
into the soil at the rate of 1.25 mm per minute. Reading of the load are taken at
penetrations of 0.5, 1.0, 1.5, 2.0, 2.5, 4.0, 5.0, 7.5, 10.0 and 12.5 mm (The maximum
load and penetration is recorded if it occurs for a penetration of less than 12.5 mm). The
plunger shall be raised and the mould detached from the loading equipment. About 20 to
50 g of soil shall be collected from the top 30 mm layer of the specimen and the water
content determined.
The penetration test may be repeated as a check test for the rear end of the sample.
6 CALCULATIONS
California Bearing Ratio - The CBR values are usually calculated for penetrations of
2.5 and 5 mm. Corresponding to the penetration value at which the CBR values is
desired, corrected load value are taken from the load penetration curve and the CBR
calculated as follows:
100... ×=s
T
P
PRBC
PT =corrected unit ( or total ) test load corresponding to the chosen penetration from the
load penetration curve, and
PS =unit (or total) standard load for the same depth of penetration as for Pr taken from
the table presented above.
7 RESULTS
The CBR at 2.5 mm penetration
The CBR at 5 mm penetration
Design CBR8 DISCUSSIONS
Generally, the CBR value at 2’5 mm penetration will be greater than that at 5 mm
penetration and in such a case, the former shall be taken as the CBR value for design
purposes. If the CBR value corresponding to a penetration of 5 mm exceeds that for 2.5 Prepared by Received by Approved by Issued by
Compiled copy if stamp is red colour
V.B. Deshmukh Geotechnical Engineering
Laboratory I/c
Dr. S.B. CharhateH.O.D.
Dr. S.D. Sawarkar Principal
Dr.H.S. ChoreM.R.
Department : Civil EngineeringName of the Process: (Smooth and effective working of Civil
Engineering Department)
Doc. No: Ver. No;00
Issue No: 01 Date: 1 January 2010 Date: Page:1/40
mm, the test shall be repeated. If identical results follow, the CBR corresponding to 5
mm penetration shall be taken for design.9 PRECAUTIONS
The contact between plunger and soil must be 100% with plunger moves perfectly
vertical in order to avoid the error in load application.
The proving ring selected generally higher capacity for dense soil. DATE OF SUBMISSIONGRADESIGNAURE
10 OBSERVATIONS
CBR TEST
Density
NMC
Condition of specimen at undisturbed/remoulded/
Test : soaked/unsoaked
Type of compaction : Static/Dynamic Compaction
Light/Heavy Compaction
Proving ring capacity
Proving ring No.
Proving ring load factor ‘C’
Dial Gauge Constant
Surcharge weight usedPenetration Data
DGR PRR Penetration mm =DGR x G Load kg= PRR x C
Prepared by Received by Approved by Issued by
Compiled copy if stamp is red colour
V.B. Deshmukh Geotechnical Engineering
Laboratory I/c
Dr. S.B. CharhateH.O.D.
Dr. S.D. Sawarkar Principal
Dr.H.S. ChoreM.R.
Department : Civil EngineeringName of the Process: (Smooth and effective working of Civil
Engineering Department)
Doc. No: Ver. No;00
Issue No: 01 Date: 1 January 2010 Date: Page:1/40
Figure: Set up for CBR test
Prepared by Received by Approved by Issued by
Compiled copy if stamp is red colour
V.B. Deshmukh Geotechnical Engineering
Laboratory I/c
Dr. S.B. CharhateH.O.D.
Dr. S.D. Sawarkar Principal
Dr.H.S. ChoreM.R.