Deep Foundation Pit Support Design And Numerical Simulation For Underground

Based on the complex engineering background of underground space in this project,this paper says that the stability and deformation regularity of deep foundation pit engineering under soft soil geological conditions are studied by using various methods such as site survey,laboratory test,numerical simulation,back analysis and theoretical analysis.Based on the field measurement and indoor geotechnical test data,large-scale finite element software establishes the constitutive model of soft soil uniaxial creep and obtains the empirical formula.Based on the variation characteristics of uniaxial creep curve of soft soil,this paper compares a variety of constitutive models,and finally selects the k-b model which can accurately express the creep characteristics of soft soil,and uses the iterative optimization inversion method to unify the uniaxial creep.The results show that the model can be used to calculate the uniaxial creep of soft soil under low stress level.However,when the stress level is high,the test curve and inversion curve can not be a good fit,so the k-b model can not be used to calculate the high stress level of the single-axis creep value.Based on the finite element method and the simplified method for deep foundation pit based on equivalent continuous model,numerical simulation software COMSOL simulating real physical phenomena can be realized by solving partial differential equation.In order to establish the simplified model of two cases of whether there is groundwater,the numerical simulation results are compared and analyzed,and the maximum horizontal displacement at the bottom of the foundation pit and the surface subsidence during the excavation of the foundation pit are obtained,thereby gaining stability and deformation law of foundation pit engineering under geological condition.Through the excavation of the foundation pit,a large number of monitoring data are obtained for the monitoring items and the monitoring points which may lead to the deformation of the foundation pit.The analysis of these monitoring items and the measured data shows that the change of the groundwater level,Vertical displacement,horizontal displacement of pile top and other factors will lead to the settlement of the ground around the foundation pit.The results of a variety of factors can be obtained by prediction model established by artificial neural network.The settlement of the surface will lead to very serious consequences,so the establishment of the prediction model of soft soil surface subsidence is of great significance and can be used for future reference.