Optimization Research On Construction Technology Of Cave-pile Excavation For Pengcheng Square Station Of Line 1 Of Xuzhou Metro

In today’s rapid socio-economic development exacerbated by urbanization, construction extending from the floor to the ground floor, in order to better underground engineering construction, we innovative construction methods. Shallow Mining Method is one of them. Under cutting construction methods as diverse as step method, cross the wall method, optical method and the like. The use of PBA hole pile method in Xuzhou Peng Cheng Square subway station is also one of them.However, the current practice of empirical and theoretical research is concerned, PBA tunneling method in hole pile construction program design does not mature theoretical basis and related laws, the majority of designers is based on past experience. Subway station construction area near the built-up of ground subsidence caused by construction and surface modification requirements are more stringent. Therefore, in order to mitigate the adverse impact of construction on the different factors of ground deformation and ground subsidence caused by the impact of the construction has a certain practical significance.The background of this paper is on the Xuzhou Peng Cheng Square Subway Station Line 1, after the establishment of a two-dimensional plan view model by the use of CAD, then use ANSYS finite element software to create three-dimensional models including the establishment of the grid and the division of formation properties, then the built three-dimensional model will be impored to the FLAC3 D finite difference software to simulate at last.This paper analyzes the impact of depth、size and structure of the guide hole pilot tunnel construction sequence of these three factors on the construction process brings. Each element in building three models, the final analysis results of simulation model. Mainly in the ground deformation and ground subsidence as the final control element, dfferent designs were compared analyzed to determine the optimum design of this factor.(1) On the basis of analysis the geological conditions of the study area in details, Research on the mechanism 、 regularity and influencing factors of ground deformation caused by construction of hole-pile excavation.(2) Calculate the model of the main station, simulated the effects of different depth on the surface deformation, and suggested the optimal depth for main station.(3) Calculate the model of computing about the hole-pile excavation, simulate the surface deformation caused by different size of the pilot hole and different construction order of the pilot hole, optimize the construction process of pile-hole excavation.Due to the factors for simulation is less than the factors which influence the actual construct, therefore the settlement value of simulation may be slightly larger than the actual construction.