The Force Analysis Of Metro Deep Foundation Pit

Nowadays the city construction is swiftly and violently developing. More and more high-rise buildings and super high-rise buildings were built, and city underground space is more development and utilization. Many deep foundation pits are appeared. At present, the main work of the foundation pit is to control the force and deformation. So, the target of designing institute and construction organization is to control the force and deformation well to make the deep foundation safe and stable.This paper bases on one foundation project case of Shenzhen subway station, summarizes the research results in the past, uses theoretical analysis and numerical simulation method to analyze the force of supporting structure when excavating and supporting, then, does a systematic study about the effect factors of underground diaphragm wall’s deformation and surface settlement behind the wall. This paper’s main work and research contents are as follows:(1)Through the massive literatures’consulting and studying, this paper has discussed and summarized the status of deep foundation pit, the design of supporting structure, the design of waterproof curtain, and the design of dewatering. The paper also summarizes the method of calculation such as internal force analysis, classic soil mechanics theory and finite element method.(2)Through simulating the process of excavating and supporting, the paper uses classic soil mechanics and structural mechanics to calculate the force of supporting structure, then analyzes the dynamic change of each step, and compares with the actual situation.(3)Using finite elements software, the paper creates a3-dimensional model, with Mohr-Coulomb elastic-plastic constitutive model, simulates the process of excavating and supporting. It calculates the force and deformation of the structure, then compares with the actual situation.(4)Through the finite elements software, the paper simulates two limiting condition, one is that deformation have finished before setting up the steel support, another one is that deformation haven’t started after setting up the steel support, then analyzes the force and the deformation of each condition.(5)Through the finite elements software, picking different parameters of the supporting structure, including the thickness of diaphragm wall and plate thickness of the steel supporting, the paper summarizes the influence law of structure’s deformation with these different parameters.