Numerical Simulation Of Deep Foundation Pit Excavation Process And Optimization Of Supporting Parameters

Foundation pit engineering is a key research content in the field of geotechnical research.The study of the impact of foundation pit excavation on the foundation pit and the surrounding environment can not only provide a strong reference for the construction of foundation pits in similar regions and under similar construction conditions,but also prevent The occurrence of construction risks has a certain significance.Based on a foundation pit project in Kunming,this paper uses finite element software MIDAS to establish a three-dimensional model,verifies the reliability of the model by comparing simulated data with actual monitoring data,and analyzes pile spacing,embedded depth,pile diameter,internal support stiffness and internal support The five factors of vertical spacing affect the foundation pit and its surrounding environment.Using a combination of numerical simulation and orthogonal test method,an orthogonal test table with 4 factors and 3 levels is established to obtain optimized support parameters.The main research content and results of the thesis are as follows:（1）Use MIDAS software to build a three-dimensional finite element model combined with engineering examples,and analyze the simulation results.It can be seen that the surface settlement trend around the foundation pit is generally"sag",and the maximum settlement is located at 0.55times the depth of the foundation pit from the side of the pit;The horizontal displacement distribution characteristics of the retaining piles are"bow-shaped",and the maximum horizontal displacement is located 8.1m from the top of the pile,which is about 0.73 times the excavation depth of the foundation pit.（2）Through the variable analysis of the design parameters of the retaining pile and the internal support,the influence curve of the parameter change on the pile deformation and the surrounding ground settlement is obtained.Within a certain range,the change of pile embedded depth improves the settlement more than the horizontal displacement.The other factors have little difference in the influence of settlement and displacement,and the improvement effect brought by parameter changes is not stable.The improvement effect will gradually decrease.（3）Optimize the parameters by using the orthogonal test method with 4 factors and 3 levels.The selected factors and their influence degree are:pile diameter（B）>internal support stiffness（D）>embedded depth（A）>pile spacing（C）).Through range and variance analysis combined with budget and other factors,it is concluded that the embedded depth is 10.2m,the pile diameter is0.6m/0.8m,the pile spacing is 1.4m,and the internal support stiffness is 1.4EI,which is the optimal parameter combination.The parameter scheme is₃₁₂₃.（4）The parameters optimized by the orthogonal test method are compared with those before optimization.The optimized design scheme can effectively reduce the deformation of the foundation pit enclosure structure and the impact on the surrounding environment.