A residential multi-story building is planned to be constructed on a reinforced concrete raft resting on the soil formation shown in the figure below. This requires excavation of 5 feet below original ground surface before the construction. Determine the geostatic effective vertical stresses at points a and b (center of the clay layer) before excavation. Determine the induced effective vertical stresses at points a and b (center of the clay layer) due to building construction (remember to factor in the excavation). Using influence charts Using 2:1 stress distribution method 10 ft 12 it 5 ft US 100 ft 120 ft x 100 ft q= 2 ksf 120 ft SAND Y = 100 pcf Yoat - 100 p-f CLAY Year 112 pc: 78 GWT