Study On The Force Or Deformation Laws Of Deep Foundation Pit In The Island During Construction And The Optimization Of Inner Support

The stress and deformation of supporting structure and surrounding environment is caused by disturbance of soil induced by excavation of foundation pit. According to the difference of structures, geological conditions and construction methods, the stress and deformation was different. And because of the imperfect theories of foundation pit design and the uncertain geological conditions, the value of safety factor for Pit design is high which cause huge losses in foundation pit construction. This paper is based on the research project of The Fifth Construction Bureau of China Railway (The key construction technology research of JuZiZhou station) and the background of Changsha JuZiZhou station foundation pit, used the field measurement and numerical simulation method to study the deformation and dynamic optimization design of deep foundation pit excavation, main content is as follows:(1) Combined numerical simulation with monitoring measurement to study the laws of the force or deformation for JuZiZhou station foundation pit and judge its stability, at the same time, to offer the theory and measurement data to the foundation pit optimization;(2) According to the characteristic of obvious water level change, analysed the force and deformation in the excavation process under different water level conditions by numerical simulation method, and combined the regulation of field measured water level of JuZiZhou station, proved that the deep foundation pit under low water level has a certain space for optimization. It is necessary to undertake optimizing designing in order to achieve economical goal and save the construction period;(3) Based on the foundation of the laws of the force and deformation of construction under low water level, put forward an optimization scheme of JuZiZhou Station deep foundation pit;then analysed the stress and deformation law of the optimized scheme excavation through numerical simulation, and proved its rationality. In order to avoid the negative effect of the heavy rainfall and other factors on the stability of foundation pit and the safety of pit construction, the security process control measures is proposed according to the characteristics of the JuZiZhou deep foundation pit.