Structure Design And Parameter Influence Analysis Of Pile-anchor Support In Deep Foundation Pit

China’s urbanization construction has always been a major direction of national attention.At the beginning of the reform and opening up,China’s urbanization level was only less than 20%.Later,because of the country’s strong support to the construction industry,China’s urbanization construction has made brilliant achievements,and in this year’s "fourteenth five-year plan" clear requirements to further strengthen the construction of modern cities,so the construction of domestic high-rise buildings and the development of underground space will continue to maintain a strong momentum.The support of deep foundation pit often determines the success or failure of foundation pit construction.In the existing support technology,pile-anchor combined support can not only save cost,but also adapt to the harsh construction environment,so the engineering application in Shenyang area is relatively mature.However,the research on the design theory of this new supporting technology is not perfect at present,which leads to the frequent occurrence of pit accidents.In this paper,based on the foundation pit project of an underground garage in Shenyang city,after comprehensively considering the properties of sand and the influence of surrounding vehicles,the supporting structure is proposed to adopt pile-anchor combined support,and the support scheme is further optimized with calculation and analysis software,so as to reduce the negative impact of foundation pit excavation on economy and environment.The main research contents of this paper are as follows:In this paper,the research progress of pile-anchor support is discussed firstly,and the structure,action mechanism and theoretical calculation of pile-anchor support design are systematically described.Secondly,the basic theory of finite element method is summarized,and the reliability of finite element analysis is verified by a typical example of a project in Shandong province.Thirdly,through the MIDAS software research and analysis of factors that may affect the stability of foundation pit,the research shows that:the embedded depth of pile has no obvious influence on the deformation of foundation pit,while the pile diameter,anchor cable prestress,anchor bolt Angle,anchor bolt position have a strong sensitivity to the stress and deformation of foundation pit,so attention should be paid to the design.Finally,using the engineering data collected in the early stage,the calculation theory is applied to a practical engineering case in Shenyang,and the design parameters of pile row and anchor cable in the enclosure scheme of deep foundation pit are determined by referring to the influence rule of parameter changes on foundation pit in the previous chapter.MIDAS and Lizheng software were used to simulate the optimization scheme respectively,and the displacement and internal force diagram of the supporting structure were derived.The differences and causes of the simulation results of the two different software were compared and analyzed,from which the position of the maximum deformation of pile side could be roughly judged.The research results could provide reference for the design of foundation pit supporting in sandy soil area.