2) Table 1 contains data obtained from consolidated undrained tests on soft clay. You need to determine the shear strength parameters in term of total stress and effective stress. A different specimen of the same soil is also tested in undrained triaxial compression at a cell pressure of 150 kN/m2, and fails when the deviator stress is 75 kN/m2. Calculate the pore pressure in the specimen failure. In your opinion, what is the differences between total stress and effective stress? Table 1 Result from consolidated undrained tests Cell pressure during consolidation and shear (kN/m²) At failure Pore water pressure (kN/m²) Deviator stress |(kN/m³) 200 120 120 400 250 240 800 480 460

2) Table 1 contains data obtained from consolidated undrained tests on soft clay. You need to determine the shear strength parameters in term of total stress and effective stress. A different specimen of the same soil is also tested in undrained triaxial compression at a cell pressure of 150 kN/m2, and fails when the deviator stress is 75 kN/m2. Calculate the pore pressure in the specimen failure. In your opinion, what is the differences between total stress and effective stress? Table 1 Result from consolidated undrained tests Cell pressure during consolidation and shear (kN/m²) At failure Pore water pressure (kN/m²) Deviator stress |(kN/m³) 200 120 120 400 250 240 800 480 460

Principles of Geotechnical Engineering (MindTap Course List)

9th Edition

ISBN:9781305970939

Author:Braja M. Das, Khaled Sobhan

Publisher:Braja M. Das, Khaled Sobhan

Chapter12: Shear Strength Of Soil

Section: Chapter Questions

Problem 12.18P

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A CD triaxial compression test conducted on a clay specimen revealed that c'=5 kPa and o'=22°. What is the major principal stress at failure if the confining pressure is 35 kPa? Solve the problem graphically and then analytically.
24.A series of consolidated, undrained triaxial tests were carried out on specimens of asaturated clay under no backpressure. The test data at failure are summarized:Confiningpressure (kPa) Deviator stress(kPa) Pore waterpressure (kPa) 150 192 80300 341 154450 504 222 a. Draw the Mohr circles and find the cohesion and friction angles in terms of effectivestresses.b. Compute Skempton’s A- parameter at failure for all three specimens.c. Is the soil normally consolidated or over consolidated? Why?d. Another specimen of the same day that was consolidated under a cell pressure of 250 kPa wassubjected to a consolidated, drained tri axial test. What would be the deviator stress at failure?
Three specimnens of clay having a small air-void content were tested in the shear box. Shear loading was started immediately after the application of the normal load and was completed in 8 minutes. The results are as follows: Normal Stress (kN/m2) Shear stress at failure (kN/m2) O Find the apparent cohesion of the clay. Find the angle of shearing resistance of the clay. What value of c would be obtained from an unconfined compression test on 145 241 337 103 117 131 the same soil?
2. A series of consolidated, undrained triaxial tests were carried out on specimens of a saturated clay under no backpressure. The test data at failure are summarized: Confining Pressure (kPa) Deviator Stress (kPa) Pore Water Pressure (kPa) 150 192 80 300 341 154 450 504 222 a. Draw the Mohr circles and find the cohesion and friction angles in terms of effective stresses. b. Compute Skempton’s A-parameter at failure for all three specimens. c. Is the soil normally consolidated or overconsolidated? Why? d. Another specimen of the same clay that was consolidated under a cell pressure of 250 kPa was subjected to a consolidated, drained triaxial test. What would be the deviator stress at failure?
A sample of dry sand is tested in direct shear. Theshear box holding the sample has a circular crosssection with a diameter of 50 mm. The normal(compressive) load imposed is 200 N. The sam-ple shears when the shear force is 130 N.(a) Determine the test normal stress and shearstress at failure.(b) Determine the angle of internal frictionfor this soil.(c) What is the probable condition of the testedsample (dense, loose, etc.)?
A clay sample was tested in the laboratory for unconfined compressive test. Determine the undrained shear strength if the unconfined compressive strength is 50kPA. (Answer in kPa only value without unit.)
Three specimens of clay having a small air-void content were tested in the shear box. Shear loading was started immediately after the application of the normal load and was completed in 8 minutes. The results are as follows: 241 117 3 3 Normal Stress (kN/m²) 145 Shear stress at failure (kN/m²) 103 Find the apparent cohesion of the clay. 337 131 Find the angle of shearing resistance of the clay. What value of c would be obtained from an unconfined compression test on the same soil?
A consolidated tri-axial test was conducted on a normally consolidated clay. The results were as follows: Chamber confining pressure = 326 kPa, Deviator stress = 414 kPa. Compute for the shear stress on the failure plane in kPa. Round off to two decimal places.
Ex A clayey soil specimen was tested in the unconfined compression test. At failure, the unconfined compressive strength (= 100 kPa) and the failure plane inclined at an angle of (50%) with respect to major principal plane. From CD test, the shear strength parameters for the same soil are (30 kPa and 20°). a) Is the soil specimen saturated or not, and why? b) Find the values of shear strength parameters with respect to total stresses. c) Find the value of pore water pressure at failure.
5. A consolidated, undrained triaxial test is being carried out on a normally consolidated clay where c - 0 and p'= 26'. The triaxial specimen was consolidated under a cell pressure of 300 kPa and backpressure of 80 kPa. Skempton's A parameter at failure is estimated to be 0.80. The drainage valve has since been dosed and the vertical deviator stress increased to failure. What would be the deviator stress and pore water pressure at failure?
During a triaxial test, the porewater pressure at failure is 80 kPa. If the total normal stress is 245 kPa and the soil has a cohesion of 12 kPa and ø' of 30°. Q: What is the shear strength of the soil considering effective stress? Round off your answer to the whole number.
Problem 3: A vane shear test was conducted on a soft clay. The vane was 112 mm in height and 70 mm in diameter. It was pressed and fully penetrated into the clay with an applied torque, T. The test gave a result of corrected undrained shear strength of 34.65 kPa with a liquid limit of the soil equal to 60 and a plastic limit of 25. Determine the following: a) the torque T applied b) the unconfined compressive strength of clay c) the unconfined compression strength of clay in the remolded state if the soil sample has a sensitivity of 3.5.