Maintenance Design Of Deep Excavation Of Subway Station And Its Stability Assessment

Based on the South Pit of Senlin Park Station of Beijing Olympic Subway branch, the maintenance plan and construction method are given. The main factors affecting the stability of deep subway excavation are studied with the in-situ monitoring, FEM simulation and theory analysis. The deformation laws of the deep excavation of subway station are obtained, and the stability assessment of the excavation is accomplished.The studying results are as follows. The maintenance plan of South Pit of Senlin Park Station is reasonable. The excavation method of separated layer and little portion excavation is effective to reduce space-time effect during the construction process. The horizontal displacement value of pile top is an important index to the safety condition of the maintenance structure, and reflects the deformation characteristics of the maintenance structure, especially the pile top. Excessive horizontal displacement value of pile top is always the precursor of the destroy of maintenance structure. The place and time setting steel pile brace influence the excavation stability obviously, and is useful to reduce the deformation and moment of maintenance structure. Otherwise the thermal stress influences the steel pile brace. The in-situ monitoring result shows that the pretension force is a little large, which causes some waste. Deep excavation of subway station is a complex system project. There are many factors affecting its stability. The influence factors affect each other. During the excavation process, the stress and deformation of the excavation and maintenance structure change with time and space. Monitoring information is very important to the foundation pit stability.