Study On Optimization And Deformation Control Of Support Structure In Step Excavation Of Foundation Pit

Since the 21st century,with the rapid development of economy,more and more high-rise buildings appear in people’s vision,and the corresponding pit project softens.At present,there is still no optimal computational analysis theory for the problem of pit engineering,but the development of computer has brought a new analysis method to the research of pit engineering.People began to apply numerical simulation methods to the problems of pit engineering,through the simulation of the pit excavation process to find out the possible safety hazards,and then guide the actual construction to ensure its safety,so as to avoid economic losses and casualties.With the foundation pit project of Shanghai impression residential district in Shenyang City as the background,the FLAC~3DD simulation software is used to calculate and analyze the excavation process of the pit under the two different support ingesting methods of large diameter pile and small diameter pile anchor,and obtain the variation law of the support structure and the surrounding soil displacement in two different cases,and the length of the pile,The effect of pile diameter and pile spacing on the pile support structure.At the same time,the support structure and the surrounding soil displacement are monitored by monitoring instruments,and the resulting data are compared with the simulation results,and the following conclusions are obtained:(1)Numerical simulation results show that both the pile support structure and the pile anchor support structure can prevent the rock and soil from moving into the pit,thus ensuring the stability of the foundation pit excavation process.However,from the numerical simulation results,economic cost and construction duration and construction technology three aspects,the large diameter pile support structure is more suitable for the pit project.(2)By analyzing the influence of various factors on the deformation law of the pile support structure,it can be seen that when the pile length and pile diameter reach a certain extent,the effect of controlling the deformation of the pit soil by increasing the pile length and pile diameter is not obvious.The pit selection pile length of 20m,the pile diameter of 1.0m is economical and safe,and the pile spacing in the range of 1.4m to 1.5m,the most safe and reasonable.(3)Through the finishing and analysis of the monitoring data,it is found that the top level of the support structure and the vertical displacement,the deep horizontal displacement of the support pile and the surrounding surface subsidence displacement are all within the control range,and there is a safety margin,indicating that the pile support structure can meet the stability requirements of the pit.(4)Through the study and comparison of the simulation results and monitoring results,it is found that the variation of the deep horizontal displacement of the support ingress and the surrounding surface subsidence displacement is basically the same,the position of the maximum displacement is similar,and the simulation value of the horizontal and sedimentary displacement is slightly less than the monitoring value,but very close.The paper has a figure of 48,table 24,references 56.