For a laboratory consolidation test on a clay specimen (drained on both sides) the following results were obtained: Thickness of clay soil= 25 mm; P_1 = 50 kPa; P_2 = 120 kPa; e_1 = 0.92; e_2 = 0.78; Time for 50% consolidation= 2.5 min. Tv = 0.197. Determine the coefficient of compressibility in m2/kN. a.2.56 x 10^-2 b.1.081 x 10^-3 c.1.23 x10 ^-5 d.1.31 x 10^-7

4) In a oedometer test a specimen of a saturated clay 21 mm thíck reaches 50% consolidation in 10 minutes. How long would it take a layer of this clay 6 m thíck under the same drainage conditions to reach 90% f consolidation under the same stress and drainage conditions? Use the following relationships between the average degree of consolidation, U and time factor, T,: U =T, for Us 50% U =1-- for U>50% No need for calculation, please write only the results.

Two drained triaxial compression tests are carried out on "identical" specimens of clean sand. In each test, a fully saturated specimen is consolidated to a confining stress and then failed by increasing the vertical stress. The test results are summarized in the following table. Assume the specimens in these two tests are uniform and have the same density. Cell pressure Deviatoric stress q (kPa) σ3 (kPa) Test No. Test 1 (Drained) Test 2 (Drained) Test 2a (Undrained) 100 200 200 Peak stress state 270.0 540.0 150.0 Residual state (or critical state) 200.0 400.0 70.0 (a) Using the results of Tests 1 and 2, determine the effective friction angle of the sand at peak failure state. (b) What is most likely the orientation of the shear failure plane in Test 1? (c) When repeating Test 2, the technician did not open the drainage valve by mistake when shearing the specimen after consolidation. In other words, the consolidated specimen was sheared under the undrained condition. The maximum…

Note) For soil sample in Table 2, initial thickness of sample = 14.31 mm, sample area = 2827.433 mm^2, dry weight measured at the end of test = 52.53 g, specific gravity = 2.7 Also, Determine the compression index and expansion index Please show graph