Deformation And Stability Analysis Of Deep Foundation Pit Pile-anchor Supporting Structure And Software Development

The pile-anchor support structure of deep foundation pit,as a support form in foundation pit engineering,is widely used in engineering because of its reasonable stress,good stability and low cost.There are usually two calculation methods for foundation pit stability:limit equilibrium method and strength reduction method.There are usually two calculation methods for the lateral displacement of the pile body:p-y curve method and finite element method.In the design process of pile-anchor supporting structure of deep foundation pit,deformation and stability are often considered separately.In this paper,based on the existing calculation theory of deformation and stability,the relationship between deformation and stability is theoretically established,and the following work is completed:(1)This article combines the calculation theory of finite element method and limit equilibrium method to search the most dangerous slip surface,and establishes the overall sliding deformation and total anti-slip moment of the foundation pit according to the nonlinear stress-strain relationship of the slip surface and loess under plane strain The nonlinear relationship between.In the process of calculating the soil resistance due to the overall sliding deformation,the polar geometry equation in elastic mechanics,the strain circle,and the relationship between the large principal strain and the small principal strain are introduced in this paper to establish the overall sliding deformation and the main strain of the shear zone soil.Relationship.At the same time,this paper introduces the additional stress method to consider the effect of excavation of the foundation pit and the change of the anchor cable tension on the small principal stress of the soil in the shear zone.Finally,based on the stress circle,this paper analyzes the resistance of the soil along the crack surface due to the overall sliding,and establishes the relationship between the overall sliding deformation and the total anti-slip moment.This paper also analyzes the relationship between the overall stability of the foundation pit and the overall deformation according to the relationship between the overall deformation and the total anti-slip moment,and calculates the overall deformation caused by the total sliding moment in combination with the slip surface and ground load.The analysis shows that:the earth excavation and the change of the anchor cable tension have a greater influence on the small principal stress of the soil in the shear zone;the total anti-slip moment increases with the increase of the overall sliding deformation;the overall stability safety factor of the foundation pit follows the overall sliding deformation Increase and decrease.(2)In the process of overall deformation of the foundation pit,the embedded end of the pile bottom slides integrally with the soil.In this paper,the lateral displacement and rotation angle of the pile bottom caused by the overall deformation are calculated based on the overall rotation angle and the position of the slip surface,and combined with the earth pressure extracted from the finite element results to calculate the lateral displacement of the pile body.By comparing the calculation results of the lateral movement of the pile body,it can be seen that the displacement of the pile bottom caused by the overall sliding deformation has a greater influence on the lateral movement of the pile body.(3)This article implements the modeling process and calculation theory through the ABAQUS secondary development program written in python language,which simplifies the process of model establishment,result analysis and data visualization,and improves the practical application value of the theory in this article.