4. Triaxial tests were carried out on 54-mm-diameter intact rock specimens. The applied confining pressures and the principal stress differences at failure are summarized below. Confining 0 5.0 10.0 15.0 20.0 25.0 pressure (MPa) Principal stress 59.5 87.5 116.0 139.5 167.5 192.5 difference (MPa) Plot ₁ against 63 at failure and determine the uniaxial compressive strength and the friction angle of the intact rock.

4. Triaxial tests were carried out on 54-mm-diameter intact rock specimens. The applied confining pressures and the principal stress differences at failure are summarized below. Confining 0 5.0 10.0 15.0 20.0 25.0 pressure (MPa) Principal stress 59.5 87.5 116.0 139.5 167.5 192.5 difference (MPa) Plot ₁ against 63 at failure and determine the uniaxial compressive strength and the friction angle of the intact rock.

Principles of Foundation Engineering (MindTap Course List)

8th Edition

ISBN:9781305081550

Author:Braja M. Das

Publisher:Braja M. Das

Chapter6: Vertical Stress Increase In Soil

Section: Chapter Questions

Problem 6.13P: Redo Problem 6.12 using Figure 6.15. 6.12 Refer to Problem 6.1. Using Eqs. (6.3) and (6.29),...

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Q: An axial compressive load of 4000N was conducted on body of rock has a cross section 0.05 m by 0.03m. Calculate the magnitude of normal and shear stresses on a plane, where the normal stress is inclined at 70° to the axis of the block
A 42mm-diameter intact rock specimen fails in a uniaxial compression test at an axial load of 20 kN. The rock behaves according to the Mohr-Coulomb criterion, with an angle of friction 38 degrees found in the triaxial tests. A specimen of diameter 42mm would fail in a triaxial test with the confining pressure of 10MPa. The values of ??and m in the Hoek-Brown criterion that would give the same failure loads as the Mohr-Coulomb criterion, for the uniaxial and triaxial tests referred to above is respectively ?? 75.14MPa and m 7.76. Calculate by how many percent the Hoek-Brown criterion with ??and m as determined in (c) overestimates or underestimates the axial load at failure compared to Mohr-Coulomb criterion, when the confining pressure is 10MPa and when it is 20MPa.
7- During stress strain test on rock sample ,if the axial and lateral strains are 0.056 and 0.014 respectively , The Poisson ratio is; a) 0.025 b) 0.4 c) 0.25 00406933 d) 4.0
A direct shear test, when conducted on a remolded sample of sand, gave the following observations at the time of failure: Normal load = 288 N; shear load = 173 N. The cross-sectional area of the sample = 36 cm2. Determine the major principal stress in kPa. a.174.6 b.246.5 c.163.5 d.146.9
SITUATION 14: After conducting a tri-axial test on a sand sample, the normal and shearing stresses on the failure plane at failure were found to be 400 kPa and 350 kPa respectively.48. Which of the following gives the angle of shearing resistance? a. 38.79 b. 41.19 c. 48.81 d. 53.949. Which of the following most nearly gives the angle of failure plane measured from the major principal plane?a. 69.41 b. 64.40 c. 71.99 d. 65.5950. Which of the following most nearly gives the major principal stress? a. 1331.51 Kpa b. 1414.58 Kpa c. 1130.37 Kpa d. 1171.32 Kp
The equation of the effective stress failure envelope for a loose sandy soil was obtained from a direct shear test as Ss = Sn tan 36 degrees; where Ss is shearing stress, Sn is normal stress. A drained triaxial test was conducted with the same soil at a chamber confining pressure of 15 lb/in^2.1. Estimate the angle that the failure plane makes with the major principal plane. a. 63 degreesb. 54 degressc. 45 degreesd. 36 degrees2. Determine the normal stress on the plane that makes an angle of 25 degrees with the major principal plane. a. 61.24 lb/in^2b. 50.14 lb/in^2c. 13.15 lb/in^2d. 16.39 lb/in^23. Determine the shear stress (when the specimen failed) on the plane that makes an angle of 25 degrees with the major principal plane.a. 61.24 lb/in^2b. 50.14 lb/in^2c. 13.15 lb/in^2d. 16.39 lb/in^2
5. Point load tests were carried out on two sedimentary rock speci- mens of 54 mm diameter (NX core), as shown the following figure The loads P and P, at failure are 6.28 kN and 4.71 kN, respectively. Find the point load strength index I(50) in the two directions and compute the point load strength anisotropy index la(50). ПР PL 30 mm TP₁ 60 mm TP₁
b. In a triaxial compression test of a rock specimen, the radial stress is 1 MPa. The specimen fails at the maximum shear stress of 1.5 MPa. The plane on which the shear stress is one third of the maximum shear stress is oriented at the angle 0 with reference to the radial direction. Which is the value of 0? A. 19.5° B. 39° C. 9.75° D. 30°
A direct shear test, when conducted on a remolded sample of sand, gave the following observations at the time of failure: Normal load = 288 N; shear load = 173 N. The cross-sectional area of the sample = 36 cm2. Determine the minor principal stress in kPa. Show the free body diagram. a.53.5 b.136.5 c.36.9 d.64.5
20 - During stress strain test on rock sample ,if the axial and lateral strains are 0.048 and 0.012 respectively , The Poisson ratio is; a) 0.25 b) 4.0 0.025 0406933 d) 0.4
A clayey soil has a drained angle of friction of 28° and cohesion of 30 kPa. In the triaxial test of the same sample, the maximum shearing stress is 70 kPa.1. Compute the all around pressure for failure to occur. a. 25.62 kPab. 28.62 kPac. 20.51 kPad. 22.68 kPa2. Calculate the normal stress at maximum shear. a. 86.51 kPab. 96.52 kPac. 46..51kPad. 92.68 kPa3. Determine the major principal stress at failure. a. 186.41 kPab. 136.52 kPac. 158.70 kPad. 162.68 kPa
Redo Problem 6.12 using Figure 6.15. 6.12 Refer to Problem 6.1. Using Eqs. (6.3) and (6.29), estimate the average stress increase (av) below the center of the loaded area between depths of 3 m and 6 m. 6.1 A flexible circular area is subjected to a uniformly distributed load of 150 kN/m2 (Figure 6.2). The diameter of the load area is 2 m. Determine the stress increase in a soil mass at points located 3 m below the loaded area at r = 0, 0.4 m, 0.8 m, and 1 m. Use Boussinesqs solution. Figure 6.2 Increase in pressure under a uniformly loaded flexible circular area