Finite Element Analysis And Comparison Of Different Types Of Row Pile Retaining Structures

With the rapid development of urban construction,in order to solve the problems such as land tension and inconvenient transportation,many cities in China began to build metro,and a large number of deep excavations appeared.At present,there are still some problems in the excavation of metro station,which are worthy of further study and optimization to ensure the security and economy of excavation.This paper selects the single row piles,inner supporting piles and double-row piles as the research objects,ABAQUS finite element software is used to simulate the internal force and deformation of each retaining structure during excavation,and the influences of some important parameters are studied by using the variable control method.The main research conclusions are as follows:(1)Inner supporting piles retaining structure is still the first choice in the deep excavation of metro station.Cantilevered single row piles retaining structure is only suitable for shallow excavation with good soil.Double-row piles retaining structure must be combined with other supporting system when used in deep excavation.(2)When the row distance of double-row piles increases,the structure will gradually lose the integral advantage of portal frame.So the row distance of double-row piles should be carefully selected.(3)The increase of braces' stiffness can reduce the deformation,bending moment and subsidence in a certain extent.But blindly increasing the braces' stiffness to improve supporting effect is inadvisable.It will lead to excessive braces' volume,inconvenient construction and capital waste.(4)The change of braces' positions will have a great impact on the internal force of retaining structure,but relatively small impact on the deformation of excavation engineering.Position of the first brace moving up properly is beneficial to control the displacement at the top of pile.The change of the second brace's position will significantly affect the internal force of the structure.The maximum bending moment of the pile will be reduced with the decrease of the last brace's position.There are many factors affect the supporting effect of deep excavation engineering.Based on the results of numerical simulation analysis,some suggestions are put forward in this paper.These suggestions are convenient for designers to choose the best type of retaining structure,and have some practical significance.