Principles of Foundation Engineering (MindTap Course List)
8th Edition
ISBN: 9781305081550
Author: Braja M. Das
Publisher: Cengage Learning
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The profile at a site consists of 5 m of sand overlying 10 m of compressible clay, which in turn overlies a dense sand. The water table is at the top of the profile. The total unit weight of the top sand is 19 kN/m3, and that of the clay is 18 kN/m3. The cv of the clay is estimated to be 5 x 10-3 cm2/sec. Initially the clay is normally consolidated. It is planned to place a temporary fill that will exert a vertical load of 200 kPa over the entire site. How long must the fill be in place so that, after it is removed, the maximum past pressure at every point in the clay is at least 50 kPa larger than the vertical effective stress that existed before the fill was placed?
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- In general, clays tend to have a more pronounced failure: -True -Falsearrow_forwardA stratum of normally consolidated clay 7 m thick is located at a depth 12m below ground level. The natural moisture content of the clay is 40.5 per cent and its liquid limit is 48 per cent. The specific gravity of the solid particles is 2.76. The water table is located at a depth 5 m below ground surface. The soil is sand above the clay stratum. The submerged unit weight of the sand is 1 1 kN/m3 and the same weighs 18 kN/m3 above the water table. The average increase in pressure at the center of the clay stratum is 120 kN/m2 due to the weight of a building that will be constructed on the sand above the clay stratum. Estimate the expected settlement of the structure in cm. a. 9.55 b. 4.96 c. 4.83 d. 23.3arrow_forwardQuestion Attachedarrow_forward
- A ground profile consists of 2m silty sand underlain by 3m of clay. The ground water table is 3m below the ground surface. The sand has a unit weight of 14kN/cum. The clay has a unit weight of 16kN/cum above the water table and 20kN/cum below the water table. Determine the Total stress at the surface of the water table (kPa). Determine the effective stress at the bottom of the clay layer (kPa). Determine the effective stress 1m from the bottom of the clay layer (kPa). Please answer this asap. For upvote. Thank you very mucharrow_forwardA consolidated-drained triaxial test on a sand yields the results:All-around confining pressure = σ3 = 30 lb/in2Added axial stress at failure = Δσ = 96 lb/in2Determine the shear stress parameters (i.e., Φ' and c')arrow_forwardsand layer 5m thick is underlain with a thick layer of clay. the sand has a void ratio of 0.52 and specific gravity 2.64. The clay has a water content of 42% and specific gravity of 2.64. The ground water table is located 3 m below the ground surface. The sand above the water table is 30% saturated. a.) Determine the unit weight of the clay b.) Determine the total stress at a depth of 10 m below the ground surface. c.) Determine the effective stress at a depth of 10m below the ground surface.arrow_forward
- A 10 m thick sand layer is underlain by 8 m thick clay layer. The groundwater is found to be at 3 m below the surface at the present time. In the Past (long time ago) the ground water table was at 6 m below the ground surface. The sand unit weight, ymoist=18 kN/m³ and the clay saturated density y«at = 17 kN/m³. Required: A) Total stress, pore pressure and effective stress at points A, B and C in Both Cases? B) Calculate the over consolidation ratio (OCR) at the midpoint of the clay layer? A Present groundwater level Sand Y= 18 kN/m3 10m 3m Current B Case 4m A Clay y= 17 kN/m3 C 4m A Sand Past groundwater level Tem 10m Y= 18 KN/m3 Previous B Case 4 m A Clay y= 17KN/m Carrow_forwardAdry sand is known to have an angle of internal friction equal to 35°. What is the maximum major principal stress that the soil can withstand when the minor principal stress is 20 psf?arrow_forwardThe coefficient of earth pressure at rest for a sand having the Poisson's ratio value of 0.25 is. ?arrow_forward
- A CU triaxial test was carried out on a silty clay that was isotopically consolidated using a cell pressure of 125 kPa. The following data were obtained: Axial load (kPa) 0 5.5 11.0 24.5 28.5 35.0 50.5 85.0 105.0 120.8 Axial strain, E₁ (%) 0 0.05 0.12 0.29 0.38 0.56 1.08 2.43 4.02 9.15 Au (kPa) 0 4.0 8.6 19.1 29.3 34.8 41.0 49.7 55.8 59.0 (a) Plot the deviatoric stress vs. axial strain and excess porewater pressure vs. axial strain, respectively. (b) Determine the undrained shear strength (su). (Note: we assume that the sample reaches failure). (c) Determine the total principal stresses (0₁,03) and the effective principal stresses (0₁, 03') at the failure, respectively.arrow_forwardQuestion 7 During the glacial period, the in situ stress of a clay formation was approximately 20,000 psf. Today, the in situ stress of that same clay is approximately 9500 psf. Which of the values below are most likely the OCR of the clay? O 1.65 O2.10 O 0.50 1.00arrow_forwardPlease show the solution.arrow_forward
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