Question

Question 2 The soil profile at a level site consists of a 3-m thick layer of sandy clay, overlaying an 8-m thick layer of loose sand, overlaying stiff gravelly clays that extend to depths greater than 20 m. The water table is at a depth of 2 m and the ground water is initially hydrostatic. The total unit weight of the upper sandy clay, above or below the water table, is 18 kN/m3. The total unit weight of the loose sand layer is 20 kN/m2. The coefficient of lateral earth pressure at rest (Ko) in the loose sand is estimated to be 0.5 Two piezometers (water pressure sensors) were installed that essentially measure the water pressure. Piezometer A is positioned at a depth of about 4 m, while Piezometer B is positioned at a depth of about 10 m (a) For the initial conditions, determine: (i) where the water levels (relative to the ground surface) would be in both piezometers, and () the average hydraulic gradient between the slotted intervals of the two piezometers (b) For the initial conditions, determine the total horizontal stress at the depth of the slotted interval for Piezometer B Suppose an earthquake causes liquefaction (100% excess pore pressure ratio) in the loose sand layer Determine: i) where the water levels (relative to the ground surface) would be in both piezometers if they had sufficiently tall "riser" sections - ie., portions that extend above ground, and (ii) the average hydraulic gradient between the depths of the slotted intervals for the two piezometers

Answer 1

Answer 18Km Sardy clay Em oose Sand. tom m2 20m Stand pipe To Qetater level m tee pizometer guate level hess = o guould etecine we teat at hSoith ckg .. ZPizomeler head Sat for A at AA 9.81 XZA 12 X3 20 ZA7.4m from atoore 74-4-3.4m GL 8x3t7x20 ZB 44 above GLr 19.4-10 from

3M mM T 7m at at ouggume Same Ko at a aPa K, Sh KoSh 8h at , P +9.81x = 27-81 kN at c 32.1u5 KN