Research On How PBA Construction Method Affects The Ground Surface Subsidence Based On Chaoyang Park Station

With the rapid development of subway construction, the construction environment where the subways are built are more and more complicated.When the construction is hindered by the heavy traffic on the ground and the pipelines underground, PBA construction method can overcome the disadvantages to ensure that the construction is smooth. Surface subsidence, which endangers the safety of buildings and structures nearby, will happen when using the PBA method to excavate the pilot tunnels. Hence it is of great importance to study how the construction using PBA method affect the surface subsidence. Based on the underground excavation section of Chaoyang Park subway station, use FLAC3D to simulate the whole process of pilot tunnels excavation. The validity of the simulation model can be proved after comparison of the results between numerical simulation and in-situ monitoring. Analyze the mechanism how pilot tunnels excavation affect the surface subsidence, and discuss the variation of surface subsidence when the sequence of tunnel excavation is altered. The main points to research are in the following:Based on the underground excavation section of Chaoyang Park subway station, this paper uses finite difference software FLAC3D to establish the model to simulate the process of pilot tunnel excavation. The validity of the model can be proved after the comparison of results between numerical simulation and in-situ monitoring.On the basis of the validity of simulation model, use results both from simulation and from in-situ monitoring to study each step of excavation affects the surface subsidence.On the basis of the validity of simulation model, use FLAC3D to simulate the process of changing the sequence of pilot tunnels excavation in order to find a better construction method to reduce the surface subsidence. This provides reference to similar engineering.