Assume that the compressible soil shown in Figure 1 consists of a clay layer 10 ft thick. A laboratory ocdometer test made on a sample from the center of the layer indicates the following: Initial void ratio, e, = 1.10, Saturated density, y= 115 Ib/f Existing overburden pressure p, = 0.7 tons/ft Pre-consolidation pressure, P. = 2.2 tons/ft? Laboratory compression index C, = 0.35 Swelling index C, = 0.06. Calculate the settlement of the surface of the upper incompressible layer due to the imposition of a uniform surcharge pressure of 5.0 tons/ft2. Uniform Vertical Surcharge Pressure

Assume that the compressible soil shown in Figure 1 consists of a clay layer 10 ft thick. A laboratory ocdometer test made on a sample from the center of the layer indicates the following: Initial void ratio, e, = 1.10, Saturated density, y= 115 Ib/f Existing overburden pressure p, = 0.7 tons/ft Pre-consolidation pressure, P. = 2.2 tons/ft? Laboratory compression index C, = 0.35 Swelling index C, = 0.06. Calculate the settlement of the surface of the upper incompressible layer due to the imposition of a uniform surcharge pressure of 5.0 tons/ft2. Uniform Vertical Surcharge Pressure

Principles of Geotechnical Engineering (MindTap Course List)

9th Edition

ISBN:9781305970939

Author:Braja M. Das, Khaled Sobhan

Publisher:Braja M. Das, Khaled Sobhan

Chapter11: Compressibility Of Soil

Section: Chapter Questions

Problem 11.16P

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1. The pressure versus void ratio data determined from a consolidation test on an undisturbed clay specimen are as follows: Applied Pressure (kPa) 20 40 80 160 320 640 1280 320 80 20 0 Void Ratio 0.953 0.948 0.938 0.920 0.878 0.789 0.691 0.719 0.754 0.791 0.890 (a) Plot this pressure versus void ratio data on a semi-logarithmic graph. (b) Determine the equations for the virgin compression curve and for the rebound curve for unloading starting at 1,280 kPa. (c) What are the corresponding compression and recompression indices for this soil? (d) Estimate the stress to which this clay has been preconsolidated. (After A. Casagrande.)
The following consolidation test data were obtained from an undisturbed clay specimen. Pressure (kPa) Void ratio 20 0.958 40 0.948 80 0.938 160 0.92 320 0.878 640 0.789 1280 0.691 320 0.719 80 0.754 20 0.791 1 0.89 (a) Plot the void ratio vs. the consolidation pressure curve on semilogarithmic graph paper, and estimate the pre-consolidation pressure o. (b) Determine the compression index C, for the virgin compression and the rebound index C, for the unloading starting at 1280 kPa. (c) Calculate the coefficient of volume compressibility m, for the virgin compression.
The laboratory consolidation data for an undisturbed clay specimen are as follows: e1 = 1.12 P₁ = 90 kPa e2 = 0.90 P2 = 450 kPa 1. Compute the value of the compression index. 2. Compute the value of the swell index assuming it is equal to 1/6 the value of the compression index. 3. Compute the void ratio for a pressure of 600 kPa. 4. Compute the coefficient of compressibility. 5. Compute the value of the coefficient of volume compressibility.
Below are results from three unconsolidated undrained triaxial tests performed on a fully saturated clay specimen: Test No. 1 2 Minor principal stress (psi) Major principal stress at failure (psi) 10 25 33 22 37 45 Moisture content = 21 % Determine: a) Void ratio (e) of the soil. You may use eS = wG_ (assume Gs = 2.70) %3D b) Deviatory stress at failure for each test trial c) Shear strength parameters (cu and ø). Hint: Sketch the Mohr's circles for the three trials. 3.
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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, &₁ (%) 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 (sµ). (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.
The consolidation test of a clay sample taken from a 2 m thick normally consolidated clay soil layer has been conducted and the results are shown in the table below. The average overburden stress of the clay soil layer is 50 kPa, What would the total settlement (mm) be if an additional 100 kPa loading is applied over a large area on the top of the clay layer? (Hint: void ratio is related to the sample volume) P(kPa) 0 50 100 200 400 e 0.850 0.760 0.710 0.650 0.640
Find the C, and the "apparent" OCR for a superficial clay stratum that is 4m thick. The water is at the surface. A sample of the clay has a water content of 27.9%, and a specific gravity of 2.65. An oedometer test showed the following results: Voids Ratio 0.736 0.733 0.73 0.675 0.638 0.6 Vertical Effective Stress 15 28 60 230 480 930
Solve all parts (a, b, c)
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