Simulation Analysis On The Construction Process Of Deep Foundation Pit

With the accelerated process of urbanization,the speed of the construction of rail traffic engineering in China has jumped to a new step.But the security risks,the progress risk and the management difficulties are becoming more and more obvious.In twenty-first Century,the excavation process of deep foundation pit of subway station needs to adapt to the surrounding and underground complex environment.In order to understand the mechanical properties of the key construction process and the potential dangerous conditions of the deep foundation pit of the subway station,the following research is carried out in this paper,taking the excavation of a underground metro station in YangLuo line of Wuhan Metro as an example.?1?In order to study the construction process of layered and segmented excavation,based on the construction scheme of the main structure of the foundation pit,this paper uses a modeling method,fully considering the geometric size of the foundation pit,the slope of the excavation face,the stiffness of the supporting system,the depth of the excavation,the support sequence,the soil parameters and the boundary conditions,and the 8 construction stages of the foundation pit by using the finite element software FLAC^3D.The numerical analysis of internal force and deformation shows that the deformation value of the foundation pit is not more than the design range,and the enclosure structure has sufficient safety reserve,and the construction scheme is safe and reliable.?2?By comparing the monitoring data with the numerical simulation results,the results show that the error of most of the monitoring data and numerical simulation results is within acceptable range,and the accuracy of the model is in line with the expectation.The reasons for the discrepancy between some data and monitoring values are also analyzed.?3?A detailed analysis of the lagging dangers of common steel support erection during excavation is carried out.Based on several hysteresis schemes for calculation and calculation,the deformation values and axial force values of the corresponding state of the excavation surface are obtained.The most unfavorable form of excavation at the excavation surface was optimized,and the steel support erection scheme at the construction site was optimized.Then,aiming at the hysteresis condition of the bottom two rows of steel supports that are prone to occur during construction,the development of the deformation of the excavation surface is temporarily controlled by adjusting the preset axial force of the erected steel support,and the effect of the measures is calculated based on the numerical calculation results.The analysis shows that it is feasible to adjust the axial force of the erected steel support as a temporary measure to temporarily control the deformation of the excavation face,but the deformation value will continue to increase with the exposure time of the excavation face.?4?A numerical model with only stratified excavation is established,and the results are compared with the stratified subsection excavation model,and the applicable range of the two models is verified by the measured data.The advantages of the layered and segmented excavation model are summarized,that is,the difference is not significant in the first excavation area of the foundation pit.The results are more accurate,and the spatial effect of the two models is similar to the deep excavation of the foundation pit.The research results are helpful to solve the practical problems of the foundation pit engineering of the subway station and improve the safety of the construction process.It has important theoretical significance and practical application value.