Supporting Design And Deformation Rule Study Of Deep Foundation Pit

With the development of modern society industry,the development of underground space gradually increases;there are more and deep foundation pit projects.Reasonable supporting structure and supporting strength is the key point to deep foundation pit safety construction,and also the hot point which is concerned by geotechnical engineering technicians nowadays.Underground diaphragm wall is widely used in deep foundation pit due to its high rigidity and great integrality etc.numerous advantages,the supporting pattern of combination of underground diaphragm wall and reinforcement concrete is generally used in some super deep foundation pit construction in soft soil area etc.special stratum super deep foundation pit,but the calculation of supporting structure design,foundation pit deformation and stability analysis etc.still cannot fully meet the practical requirement of project.The Thesis focus to discuss the calculation method of underground diaphragm wall on the basis of summarizing and analyzing the deformation generating mechanism and deformation pattern of foundation pit and maintenance structure.Use the revised elastic method to do the theoretical calculation for foundation pit axial force and deformation on the background of some financial center deep foundation pit in Tianjin;Use FLAC3 D numerical software to do the simulative calculation of the surrounding road of foundation pit and supporting structure deformation,and analysis its varying pattern;Design and implement the foundation pit construction period monitoring proposal,and analyze the monitoring data.Focus to study the underground diaphragm wall deep level horizontal displacement,coping vertical displacement,interior supporting axial force and the surrounding road varying pattern,discuss the stability of foundation pit.The main study results are as the followings:(1)Do the checking calculation of stability of some financial center foundation pit in Tianjin,gets the safety factor KL 2.5,which is bigger than the maximum value of 1.8 stipulated in Technical Specification of Retaining and Protecting for Building Foundation Excavation,and it show that the retaining and protection of foundation pit is safe and stable.(2)The numerical simulation result of foundation pit deformation shows the surrounding soils continuously settling with the foundation excavation,and appears triangular distribution pattern.The bottom of foundation pit appears uplift;the uplift degree and soil horizontal displacement expand with the continuous excavation of soil,the maximum displacement of underground diaphragm wall appears in two thirds of the depth of foundation excavation area,interior support is always in press condition,the setup of interior support can effectively reduce the horizontal displacement.(3)The monitoring and analyzing result of foundation pit shows that the horizontal displacement of underground diaphragm wall shows the tendency of rising,and its rising degree varies under different construction,its deformation rate accelerates in the beginning and tends to be stable followed.Interior support shows the tendency of rising,the surrounding road settlement appears triangular pattern,all the monitoring data is less than the alarming value.(4)Compare and analyze the monitoring data with simulation value,the result shows the selection of numerical simulation model and calculation parameter is reasonable,which can provide the reference for similar project design construction.