MECHANICAL BEHAVIORS OF PILED-RAFT FOUNDATION AND DIAPHRAGM WALL IN DEEP EXCAVATION OF TAIPEI METROPOLITAN

The piled-raft foundation has been widely used in recent years to solve the low bearing capacity and the excess settlement problems of the raft foundation on the soft soil. The soft soil is reinforced by the pile and behaviors of the diaphragm wall and the raft are also modified by the pile. However, effects of the pile on the diaphragm wall and the raft have not been fully discussed in the past. In this paper, a finite element program, Plaxis-3D, is used as the numerical simulation tool. First, simulations of pile loading tests are performed to verify the input parameters and models. Then, deep excavation cases with and without the pile group in a typical Taipei Metropolitan soil profile are modeled and discussed to identify effects of the pile. Results show that the pile lowers the lateral displacement of the diaphragm wall, reduces the influence zone of ground settlement around the excavation area and modifies the deformation pattern of the diaphragm wall and ground settlement.