Question

3. A) Estimate the profiles of vertical effective stresses for the following problem from the ground surface to 4.5 m depth (same soil unit). B) What would happen to the effective stress profile if the ground water table rises to the level of the ground surface? Compute the corresponding vertical profiles of total stress, pore water pressure and effective stress. C) What would happen to the effective stress profile if the water table moves 4.5 m above the ground surface?? Compute the corresponding vertical profiles of total stress, pore water pressure and effective stress. Compare results from A), B) and C) Ground surface kN YE 18A (115 pcf) Za 1.5 m Water table Ysat 20 kN (127.4 pcf)

Answer 1

* at A: sigma = 0 y = 0 sigma' = sigma - y = 0 * at B: sigma = gamma t times 1.5 = 18 times 1.5 = 27 KN/m^3 y = 0 sigma' = 6 - 4 = 27 KN/m^3 * at C: sigma = gamma t times 1.5 + gamma_sat times 3 = 18 times 1.5 = 20 times 3 = 87 KN/m^3 y = gamma_w H = 9.81 times 3 = 29.43 KN/m^3 sigma' = sigma - y = 57.57 KN/m^3 * w.t rises to the Ground level: \r\n * at A: sigma = 0 y = 0 sigma' = 0 * at B: sigma = gamma_sat times 1.5 = 20 times 1.5 = 30 KN/m^3 y = 9.81 times 1.5 = 14.72 KN/m^3 sigma' = sigma - y = 15.29 KN/m^3 * at C: sigma = 20 times 1.5 + 20 times 3 = 90 KN/m^3 y = gamma_w times 4.5 = 9.81 times 4.5 = 44.15 KN/m^3
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