Optimization Design And Simulation Analysis On Pile-anchor Supporting Structure Of Deep Foundation Ditch

In recent years, with the development of social economy, in order to alleviate theland for construction of tension, the utilization of urban underground space is increasingyear by year. With the development of underground space, the foundation pit supportingis become a problem. In numerous support method, the pile anchor supporting structureis the most widely used in deep foundation which has convenient construction, low costand the advantages of small displacement.This paper takes a large deep excavation engineering in Baotou as a example.Using lizheng software to design and calculate the pile-anchor supporting structure andchecking computations of stability is carried out for the foundation pit stability, resistantheave, anti-overturning and embedded depth. Since then, the stress state anddeformation characteristics of foundation pit supporting structure is simulated by usingthe finite element software MIDAS/GTS. Horizontal displacement, surface settlementand stress is simulated in different working conditions, and the monitoring results iscomparative analyzed. Detail optimization and numerical simulation is carried out forthe supporting structure based on the original scheme, and compare to the originalscheme. Through the above analysis, this paper get the following conclusions：(1) During excavation process,the maximum horizontal displacement of soil in thefoundation pit part is9.8mm and the maximum of vertical subsidence displacement is10mm, the displacement values are within the specifications.(2) Vertical stress of the soil increases along with the increase of excavation depth,conforms to the distribution of soil stress. The stress concentration phenomenon appearsin the bottom of the pit. Position monitoring should be strengthen in the process ofconstruction, in order to guide the design and construction.(3) Optimize the detail parameters of the supporting structure and analysis theanchor supporting structure of the horizontal displacement and vertical displacement ofthe supporting structure to select the reasonable detail parameters. The new supporting parameters of pile diameter is0.8m, pile spacing is1.2m, the built-in depth is3.9m,anchor position is3.0m, anchor prestress is90%, pile diameter is13°. Foundation pithorizontal displacement and vertical displacement of the original reduce9.8mm and11.46mm to7.8mm and10.2mm, and the stability of foundation pit increases, theproject cost reduces compared with the original plan, so the optimization result isreasonable and feasible.