SMW Retaining Structure For The Subway Station Deep Foundation Deformation Study

On the basis of Bai Jia Hu subway station of Nanjing Subway Line 1 Southern Extension, the paper analyses on the the monitored data measured and summarizes the deformation rule of sub-surface soil movement, ground settlement around foundation pit, strut axial forces and so on. Using large-scale finite element analysis software, the paper established three-dimensional finite element model and compared with the monitored data measured, found that the result from finite element software consistent well with the measured data. Making use of the finite element method, the paper analyses the influence of different physical properties of soil, different types of the section steel, different disposition of forms, different strut axial forces to the deformation of the SMW wall. Finally, several constructive measures for reducing or eliminating the adverse effects on foundation pit are suggested. The conclusions of the numerical test are as follows:(1) Insufficient embedded depth may cause the SMW wall damage. When embedded depth meet the requirements of impermeability, increasing embedded depth of the wall show no benefit in preventing structural deformation.(2) According to different disposition forms of the section steel, the deformation of the SMW wall changed obviously. The influence caused by the change of section steel type to the deformation was insignificant.(3) Brace pre axial force has a great impact on the SMW wall displacement. Increasing brace pre axial force of the first layer can effectively control the wall top displacement. The optimum pre axial force is 80% to 100% of design value. Similarly, increasing brace pre axial force can effectively control the wall displacement. To control the wall displacement, the optimum pre axial force is 50% to 80% of design value.(4) According to the different characteristics of the effect to the SMW wall, propose some corresponding concrete measures to prevent the deformation.