Numerical Simulation Study On Pit Excavation

With the rapid development of cities constructions, exploiting three-dimension cities is necessary and significant. As a result many pit projects appear, and the excavation is becoming deeper and deeper. For pit excavation, because of long time, high costs and many difficulties in design and calculation, it is a focus for civil engineers how to reasonably calculate, design and check the braced system. In this paper the finite element model for the pit excavation and bracing of Qianhao International Square is set up, and the whole process for excavating and bracing is simulated. In the analysis air elements are used to simulate the excavated soil, and time steps are defined to simulate the process for excavating and bracing. Internal forces, deformation for the braced system and land subsidence are calculated and analyzed for every time step. Through the analysis and simulation, some conclusions are obtained as follows:(1) After the pit excavation, the earth pressure and displacement are bigger in mid part than those in tail part.(2) Finite element method can simulate whole the process for the excavating and bracing, and can simulate the installment and work of the anchors and the pre-force execution.(3) The axial forces for the anchors are changed with the excavation process. The bond length of the anchor should be calculated by the change of the axial force. The space of the anchors should be designed according to the moment change of the pile.