Three Dimensional Numerical Simulation Analysis Of Deep Foundation Pit Excavation In Soft Stratum

Large and medium-sized cities in China are mainly distributed in the coastal areas,the middle and lower reaches of rivers and the areas near lakes.It is of great significance for the excavation and utilization of urban underground space to carry out the relevant research on the underground engineering in such soft soil areas.Secondly,with the rapid development of super high-rise buildings,there are more and more deep foundation pit projects.Therefore,it is of great theoretical and practical significance to study the design and calculation of deep foundation pit in soft ground,the mechanical characteristics and deformation laws of support structure,the strength parameters of soft ground affected by deformation and the factors affecting support structure.In view of this,this paper relies on the soft stratum of the deep foundation pit project of ZTE headquarters building in Shenzhen to carry out numerical simulation analysis.The main research contents and results are as follows:(1)Through the calculation of the structure and stability of the foundation pit of ZTE headquarters building by straightening out the deep foundation pit 7.0,it is verified that the design scheme meets the requirements of the code.Finally,the problems in the simplified calculation of the counterweight platform and the back row pile are analyzed.(2)Using finite element analysis software MIDAS GTS Nx solves the problems existing in the design,modeling and calculation of Lizheng deep foundation pit 7.0,analyzes the mechanical characteristics and deformation laws of the foundation pit excavation,and finally compares the finite element numerical simulation results with the measured data.The coincidence of the comparison results proves that the finite element calculation model and soil strength parameters are reasonable,which can provide reference for similar projects in the future.(3)The strength parameters of three soft strata affected by foundation pit deformation are tested by Midas GTS NX.The results show that the cohesive force C factor is the key factor,the internal friction angle ? factor is the important factor,and the elastic modulus E factor is the general factor.(4)Using the finite element analysis software MIDAS GTS NX,through the analysis of the influence of the linear change of row distance,the diameter of the back row pile and the load on the top of the pit on the support structure,it is concluded that these three factors have little influence on the bending moment and shear force of the front row pile,and have great influence on the back row pile;the influence law of the horizontal displacement of the front row pile and the back row pile is basically the same,and the reasonable row distance is1d-3d(D is the distance of the front row pile,d = 1.8m).