The Construction Numerical Simulation And Back Analysis Parameters Of Urban Subway

Subway system is very special structural system, it not only affected by the complicated geological conditions of its location but also affected by sequence and method of excavation; besides, subway systems are mostly located in downtown area where accident in construction will cause the cracking and tilting of nearby buildings and fracture of underground pipeline and wrought inconvenience for residents. Because of the importance of stability of surrounding rock, this paper use numerical simulation and construction monitoring method to investigate the construction process of Dalian Xianggong Street Subway station.Firstly, use the numerical simulation results and monitoring data, information feedback method are adopted to process the data. Curves of settlement of shaft and transverse gallery and vault, convergence of clearance are drawn. Through regression analysis, the rate of displacement changing and displacement -time history are used to investigate the surrounding rocks stability.Secondly, simulate the excavation process by 3-d explicit finite difference software FLAC3D. The ground settlement, internal force of support structure and plastic zone under different excavation sequence are obtained and use to study the surrounding rocks,compare the monitoring results and simulation results.Last, given consideration to the difficulty in determine the parameters, combined matlab's BP neural network toolbox and monitoring data to conduct displacement back analysis. Parameters which are in good agreement with monitoring data are obtained and use to optimize numerical model.This paper combines the construction measurement and numerical calculation, studies and summarizes the ground settlement pattern and predicts the final ground settlement; analyze the stress of surrounding rocks and internal forces of supporting structure; study the stability of surrounding rocks during subway construction; using intelligent back analysis of neural network to obtain more authentic soil layer parameters to mitigate the adverse effect of parameters to ensure the results are accord with practical situation, guide the choosing of construction plan, has significant theoretical and practical meaning in preventing engineering disaster.