The Analysis And Numerical Simulation Of The Secondary Excavation In Deep Foundation Pit Supported With Pile Anchor

Along with our country urbanization speed up the pace of construction, urbanconstruction land supply has become increasingly scarce, as a result, the use ofunderground space more and more get the attention of people. But factors such as thedepth of deep foundation pit, excavation cycle long and big influence on thesurrounding buildings, complex geological conditions, frequent accidents becomerestricts the effective use of underground space. In order to seek better and morereasonable way of foundation pit supporting, cantilever pile, pile support, anchor piles,steel piles, underground continuous wall, cement-soil retaining wall and soil nailingwall were used through the experience summary and theoretical derivation. Pileanchor bracing for excavation depth, no restriction of excavation width, and theadvantages of large equipment can be used for the excavation is becoming more andmore get the favour of designer.Support scheme of pile anchor in deep foundation pit based on the application ofuniversality in the design and calculation of uncertainty, it is necessary to analysis andresearch this kind of support scheme. Based on the secondary excavation project indeep foundation pit in the central square in Changsha, Hunan province (the foundationpit excavation pile anchor bracing way after a year and a half to a certain depth,according to owner requirement, part of foundation excavation depth must be downagain) as the example, study the rationality of the "m" method to calculatedisplacement of pile end and optimization design in support scheme of pileanchor.This paper introduces several kinds of supporting forms commonly used infoundation pit firstly, emphatically describes the basic construction of supportstructure of the pile anchor and design method, and the calculation method of seismicand non-seismic soils stress.Again the first to arrive in foundation pit excavation offoundation pit deformation observation data as the basis, using Matlab software towrite retaining piles under earthquake action and non-seismic internal force anddisplacement calculation program, calculation result will be compared with themeasured data analysis, to verify the applicability of the "m" method and thereliability of the program design. Then using finite element analysis softwareMIDAS/GTS for the pile anchor supporting structure numerical simulation analysisand the excavation process, and its structure and programming calculation throughcomparison between calculation results and measured knot stick, to verify theeffectiveness of the pile anchor supporting structure and the reliability of the finiteelement analysis software. On this basis, through the theoretical analysis andnumerical simulation software, stage2to arrive in foundation pit excavationsupporting scheme optimization design of secondary in order for the future similarfoundation pit excavation supporting engineering to provide certain reference andreference value.