Extracted text: (a) Compute the intensity of passive earth lios pressure at a depth of 8m in a cohesionless sand with an angle of internal ange friction of 30° when water table rises to the ground level. Saturated unit weight of sand is 21 kN/m3; yw = 9.81 kN/m (b) A vertical excavation was made in a clay deposit having unit weight of 22 kN/m3. It caved in after the digging reached 4m depth. Assuming = 0, calculate the magnitude of cohesion.