Study On Stability Of Side Walls Of Foundation Pit At The Joint Of Adjacent Different Support Forms

Deep foundation pit engineering does not adopt a single support form based on the surrounding environment.In order to achieve an appropriate balance between safety and economy,different support forms are generally used at different locations,with different stiffness,and the distribution of soil pressure outside the foundation pit is also different.Under the construction of foundation pit excavation,different support forms produce different responses,It often leads to deformation and incongruity at the joint of support forms,making the side wall of the foundation pit at the joint a sensitive area,and even leading to engineering accidents.In response to this situation,based on a deep foundation pit project in Zhengdong New Area,Zhengzhou City,the research method of combining rational calculation,numerical simulation,and on-site monitoring is adopted to focus on the analysis of the combination of two adjacent support forms of pile anchor support and double row pile support for this foundation pit project,The distribution laws of displacement and stress near the interface are studied to investigate the problem of incompatible deformation at the interface.The research content of this article includes the following aspects:(1)The calculation of pile anchor support and double row pile support is carried out through Li zheng software,and the differences in displacement,internal force,ground settlement,anti overturning safety factor,and anti uplift safety factor of the two support structures are compared and analyzed.The calculation verifies whether the design of the support structure meets the design requirements.Through comparison,it is shown that under the same geological situation,different support forms produce different responses due to different surrounding environments;(2)Conduct numerical simulation of the pile anchor support on the east side of the foundation pit and its adjacent double row pile support and surrounding environment,analyze the changes and distribution of displacement and stress at the interface of adjacent support forms under different working conditions,analyze the differences between the pile top horizontal displacement and deep horizontal displacement of the two types of support forms,analyze the simulation monitoring points,and finally analyze the impact of foundation pit excavation on the displacement and internal force changes of surrounding buildings,The comparison shows that double row pile support has a greater stiffness,which produces greater constraints on soil mass during foundation pit excavation and effectively limits soil deformation.Pile anchor support has a smaller stiffness than double row pile support,and its pile body and soil mass behind the pile have greater deformation than double row pile support.The displacement and stress near the interface of different support structures are not uniform and smooth,with significant fluctuations and significant changes;(3)Through the collation and analysis of real-time monitoring data of the project,the focus is on comparing the on-site monitoring data and numerical simulation data of deep horizontal displacement and pile top horizontal displacement of different support forms,verifying the correctness and reliability of the numerical simulation,in order to further study the deformation mismatch problem at the junction of adjacent different support structures.