A 6-in.-high specimen of soft silty clay with a unit weight of 105 Ib/ft is tested in a resonant column device with l, =0.4. From the frequency response curve shown in Figure E6.7, deter- mine the shear modulus of the specimen. 100 35 40 45 50 55 60 Accelerometer output (mV)

: In a tri-axial test of a silty soil, the sample failed at normal stress of 475 kPa and a shear stress of 350 kPa. Which of the following gives the angle of internal friction? Compute the angle that the failure plane makes with the x-axis. Compute the maximum failure stress.

Q11: A silty sand of density index (ID or Dr) = 59% was subjected to standard penetration tests at a depth of 3 m. Groundwater level occurred at a depth of 1.5 m below the surface of the soil which was saturated throughout and had a unit weight of 19.3 kN/m³. The average N count was 15. During calibration of the test equipment, the energy applied to the top of the driving rods was measured as 350 Joules. Determine the (N₁) 60 value for the soil.

a) Following results are obtained in a series of CU triaxial tests on saturated samples of a clay. Calculate the effective shear strength parameters (c' and ') and plotting the Mohr- Coulomb failure envelope. (Hint: you can first plot the top points of the circles in q=(01-03)/2 vs. p=(₁03)/2 space.) Test number Confining (cell) Pressure (kPa) Deviator stress (01-03) (kPa) Pore pressure before shear (kPa) Pore water pressure at failure (kPa) ● 1 400 120 300 320 2 400 210 200 260 3 550 270 250 235 b) If we carry out a consolidated drained triaxial test on a specimen taken from the same clay (assume same c', '), what would be the deviator force at failure in a specimen that is consolidated under an isotropic stress of 240 kPa and pore pressure of 300 kPa. The specimen was initially 5 cm in diameter and 10 cm in height. Peak strength (i.e. failure) is reached at axial strain of 4% and volumetric strain of 2% in compression. Hints: the pore pressure is initial pore water pressure

SITUATION 5: A sand sample is subjected to direct shear testing at it's (in - situ) water content. Two tests are performed. For one of the tests, the sample shears at a stress of 400 kPa when the normal stress is 600 kPa. From these data, 15. Determine the value of the apparent cohesion. c. 230 kPa d. 221 kPa а. 100 kPa b. 179 КРа 16. Determine the corresponding angle of internal friction. a. 22.65 degrees b. 26.57 degrees c. 32.54 degrees d. 18.43 degrees

Q.64 In an unconfined compression test, a sample clay 100 mm and 50 mm in diameter fails under a load of 150 N at 10% strain. What is the shearing resistance taking into account the effect of change in cross-section of the sample? (a) 0.068 N/mm2 (c) 0.034 N/mm2 (b) 0.088 N/mm2 (d) 0.044 N/mm? Ans. (a)

An intact rock sample was subjected to triaxial testing, and the results of the tests are given below. When repeating the test at 15.0 MPa confinement, the jacket punctured, and the pore pressure built up to a value equal to the confining pressure during the test. What would be the peak axial stress? Confining pressure Axial stress at failure [MPa] [MPa] 03 (MPa) а1 (MPa) 0.0 74.0 5.0 85.0 10.0 95.0 15.0 115.0 O a. 94.5 MPa O b. 105.0 MPa O c. 115.0 MPa O d. 92.0 MPa O e. 89.0 MPa

1. Triaxial compression tests are done on quartzite rocks, the results are shown below. (0₁+03)/2 -964.25 14500 19575 23200 29000 43210 63075 psi (01-03)/2 964.25 14500 18850 21750 26100 35960 48575 psi Comment on the applicability of each of the Mohr-Coulomb, Griffith, and Hoek-Brown criteria for the testing results.

A sample of dry sand is tested in direct shear. A normal load equivalent to 96 kPa is imposed for the test. The shearing force applied to fail the sample is increased until shearing does occur. The shear stress at failure is 65 kPa. What is the angle of internal friction f for the sand?

Can TRIAXIAL TESTS be performed on sand samples? Briefly explain. The results of an undrained triaxial test on a clay soil sample are given in table below Cell Pressure (kN/m2) 200 400 600 Additional Axial Load at Failure (N) 342 388 465 Each sample, originally 76mm long and 38mm in diameter, experienced a vertical deformation of 5.1mm.  Evaluate the stress at failure for each cell pressure given in table above. Draw Mohr Circles and determine the shear strength parameters of the soil.