Finite Element Analysis Of Pile-Anchor Optimal Design In Supporting Of Foundation Pit

Since the urbanization in China is accelerating, more and more underground space is being developed and utilized. In the meantime, the environment caused by the foundation excavation is increasingly prominent, which lead to the requirements of controlling the deformation of excavation has become stricter. Pile-anchor supporting system has been widely used for it has strong adaptability to control the deformation and be able to maintain stability and security, and the requirement of space for construction is small. It has been widely used in deep excavation as an optimization design tools. In the pile-anchor supporting system, pile spacing, pile embedded depth, anchor point and pre-stress are the important factors influencing the effect of foundation pit support. It is necessary to carry out research on parameter optimization of pile-anchor supporting system to achieve the unity of economic and security. In this paper, considering the influence of various parameters on the supporting effect, select the optimal parameters of pile anchor combination.In this paper, the current research situation and development trend on the deep foundation pit support at home and abroad are summarized. The research status on pile anchor support, the working mechanism and design theory are discussed in detail. Principle of finite element analysis on pile anchor support and constitutive model of soil are considered. Cambridge constitutive and Duncan constitutive which are used in the numerical simulation of soil are introduced. That provides a theoretical basis for finite element analysis of pile-anchor supporting system.With an example of foundation pit engineering of a high-rise building in Shenyang,3D numerical simulation of the pile anchor supporting structure is established by using the finite element software -ABAQUS. In this paper, by varying embedded depth of supporting pile, pile spacing, the Angle of the prestressed anchor cable and prestress value, get the displacement and internal force of soil and pile and make a compare analysis with the displacement and internal force under different parameter combinations. Through the comparison and analysis some conclusions can be obtained.(1) Within a certain range, the horizontal displacement and vertical stress of pile can not be reduced effectively through improving the embedded depth.(2) This project use 1.2m pile spacing which can reduce the horizontal displacement, vertical stress and effectively improve the safety factor of the pile.(3) Prestressed anchor cable can effectively adjust the stress of the pile and reduce the deformation of foundation pit. Considering the size and angle of prestressed anchor cable, the best angle range of prestressed anchor cable is 20°?25°, and prestressed size is 400kN which will bring the most ideal supporting effect.This paper not only gets the optimizational results of pile-anchor supporting system, but also provides a framework for multi-parameter optimization, which is valuable to engineering application; The conclusions and laws got from this paper may be helpful to the forecast of the construction and deformation of the pit and also accumulate some experience for construction of the foundation pit engineering.