The Study On The Stability Of Deep Foundation Pit Of Back-analysis With Multi-parameters Based On Intelligent Optimization

At present, our country has entered a golden period of development of city subway construction, also it is a key of the city planning and construction in the new period. The construction of deep foundation pit is the key process of metro construction process, and it is a system with very strong and uncertainty.In the previous excavation stability research experience, select the reliability of numerical simulation results greatly depend on the soil constitutive model and calculation parameters.Because of the soil is usually inhomogeneous anisotropic medium, nonlinear, non continuity, even for the same soil, soil parameters in different locations are often changed.The influence of construction disturbance and constant change, so how to solve the numerical simulation of soil parameters are not accurate "bottleneck" and according to soil parameters back analysis of deep foundation pit stability and deformation prediction, has become a hot topic of research at home and abroad.Based on the deep foundation pit of a subway station as engineering background, try to use a dynamic model of intelligent optimization algorithm-differential evolution algorithm to obtain soil multi-parameters with displacement optimization back analysis.The paper studies on stability of deep foundation pit based on that, the main work in the following. First of all, using Flac3 D to establish three-dimensional numerical model of the deep foundation pit with soil parameters,geological exploration report given. By the orthogonal test of each soil parameter sensitivity analysis was performed using orthogonal design method, the size of each soil parameter sensitivity determined on range method, determine the final parameters to back analysis of parameters; then using differential evolution algorithm for multi parameter dynamic optimization back analysis of displacement of each layer of sensitive parameters back analysis, which can reflect the objective function is selected as the fitness function of the construction condition, the calculation model of numerical values into positive analysis of parameters of each layer soil and will be the inverse analysis, the result of numerical simulation and the actual site monitoring data comparative analysis to verify the parameter value the rationality and accuracy of the deep excavation, ground settlement and the supporting structure of the axial force monitoring aided verification.Finally, numerical simulation of deep foundation pit stability of soil dynamic parameters are obtained, according to the value, and using the parameter close excavation state by back analysis on internal force of retaining structure of foundation pit engineering in the next step, prediction of settlement deformation and the surface, the systematic analysis of the stability of foundation pit. The research results show that the soil parameters obtained by this method is more close to the true value of soil parameters, a numerical model is established for the more close to the real state of excavation, it can make full use of the field monitoring data of foundation pit deformation.It is also accurate and reliable prediction, efficiency analysis and it can deal with the problem of deep foundation pit engineering stability.It has guiding significance and important theoretical value in the deep foundation pit of subway construction, and it is a certain reference to the similar study on stability of deep foundation pit engineering.