Geotechnical Engineering II Experiments

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Department : Civil Engineering Name of the Process: (Smooth and effective working of Civil Issue No: 01 Engineering Department) Date: 1 January 2010 Experiment No. 1 1 2

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NAME OF EXPERIMENT DIRECT SHEAR TEST AIM To determine shear parameters ( c and ) of soil in under un-drained condition 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.

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PREPARATION OF SPECIMAN Remoulded Specimens In 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.

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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. 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

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Prepared by V.B. Deshmukh Geotechnical Engineering Laboratory I/c

Received by Dr. S.B. Charhate H.O.D.

Approved by Dr. S.D. Sawarkar Principal

Issued by Dr.H.S. Chore M.R.

Compiled copy if stamp is red colour

Department : Civil Engineering Name of the Process: (Smooth and effective working of Civil Issue No: 01 Engineering Department) Date: 1 January 2010

Doc. No: Date:

Ver. No;00 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, = Shear stress is given by, = proving ring reading. 7 RESULTS The shear parameters in the un-drained conditions are cohesion c = Angle of internal friction, = 8 DISCUSSIONS In case of sandy soil the c is close to zero and value is maximum. According to Terzaghi < 28 is classified as loose sand whereas, 380> > 28 is medium dense sand and 8 >38 is very dense sand. For saturated clays = 0 .0 0 0 0

L

100 , Where is shear displacement

F , where F is the maximum shear force calculated from A

PRECAUTIONS Select 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 V.B. Deshmukh Dr. S.B. Charhate Geotechnical Engineering H.O.D. Laboratory I/c

Approved by Dr. S.D. Sawarkar Principal

Issued by Dr.H.S. Chore M.R.

Compiled copy if stamp is red colour

Department : Civil Engineering Name of the Process: (Smooth and effective working of Civil Issue No: 01 Engineering Department) Date: 1 January 2010

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Ver. No;00 Page:1/40

DATE OF SUBMISSION GRADE SIGNATURE

Prepared by V.B. Deshmukh Geotechnical Engineering Laboratory I/c

Received by Dr. S.B. Charhate H.O.D.

Approved by Dr. S.D. Sawarkar Principal

Issued by Dr.H.S. Chore M.R.

Compiled copy if stamp is red colour

Department : Civil Engineering Name of the Process: (Smooth and effective working of Civil Issue No: 01 Engineering Department) Date: 1 January 2010 OBSERVATIONS DIRECT SHEAR TEST Density, g/cc Moisture content Drainage condition Max. Size of particle Area of sample, A = 36 cm2 Length of sample, L = 6 cm Volume, V = 90 cm3 DGR PRR Displacement mm =DGR x constant

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Date Proving ring capacity Proving ring number Proving ring factor C.F. Dial Gauge constant

Shear strain %= L 100

Shear Force, F= PRR x CF

Shear stress

=cm2

F kg/ A

0 0 30 60 Note: till PRR decreases or upto 20% strain whichever reaches earlier

Prepared by V.B. Deshmukh Geotechnical Engineering Laboratory I/c

Received by Dr. S.B. Charhate H.O.D.

Approved by Dr. S.D. Sawarkar Principal

Issued by Dr.H.S. Chore M.R.

Compiled copy if stamp is red colour

Department : Civil Engineering Name of the Process: (Smooth and effective working of Civil Issue No: 01 Engineering Department) Date: 1 January 2010

Doc. No: Date:

Ver. No;00 Page:1/40

Prepared by V.B. Deshmukh Geotechnical Engineering Laboratory I/c

Received by Dr. S.B. Charhate H.O.D.

Approved by Dr. S.D. Sawarkar Principal

Issued by Dr.H.S. Chore M.R.

Compiled copy if stamp is red colour

Department : Civil Engineering Name of the Process: (Smooth and effective working of Civil Issue No: 01 Engineering Department) Date: 1 January 2010 Experiment No. 2 NAME 1 2 OF EXPERIMENT DETERMINATION

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OF

UNCONFINED

COMPRESSIVE STRENGTH AIM : To determine Undrained Cohesion of partly saturated clayey soil 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.

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PREPARATION OF TEST SPECIMEN The soil specimen to be used for test may be undisturbed, compacted or remoulded. 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. 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 Received by Dr. S.B. Charhate H.O.D. Approved by Dr. S.D. Sawarkar Principal Issued by Dr.H.S. Chore M.R.

3.2

Prepared by V.B. Deshmukh Geotechnical Engineering Laboratory I/c

Compiled copy if stamp is red colour

Department : Civil Engineering Name of the Process: (Smooth and effective working of Civil Issue No: 01 Engineering Department) Date: 1 January 2010

Doc. No: Date:

Ver. No;00 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. Remoulded Specimen The dry density and moisture content are given or obtained from proctor test to evaluate dry mass of