Deformation Analysis Of Underground Diaphragm Wall Supporting Structure Of Super-large Deep Foundation Pit

With the development of the times,more and more tall buildings appear,foundation pit engineering is also exploring in the direction of large and deep,but because the geological conditions and surrounding environmental factors of the foundation pit construction site are different,it is difficult to sum up a set of foundation pit support schemes that is effective for all engineering scenes,so for each foundation pit engineering,the importance of supporting structural deformation analysis before construction is also self-evident.Based on "Section 03 of Beijing Urban Auxiliary Center Transportation Hub Project",this paper verifies the rationality of the support structure of a super-large deep foundation pit by using construction experience and theoretical knowledge,and analyzes the deformation law of the underground diaphragm wall support structure with the help of numerical simulation software.Find effective support methods to resist deformation of the foundation pit and reduce the impact of foundation pit construction on the surrounding environment.Through the method of theoretical analysis and numerical simulation,this paper makes the preliminary analysis and puts forward the optimization scheme for the project,and uses the measured field data to verify the optimization results.The main work is as follows:(1)Combined with the site environment and the surrounding buildings in the area where the Beijing sub-center transportation hub project is located,the supporting structure form of the foundation pit project is designed and checked according to classical theory,and the rationality of the supporting structure is verified by theory.According to the theory of earth pressure and support theory,combined with the form of support,the earth pressure of the construction site is calculated,and the internal force of the supporting structure is solved to complete the calculation,design and test of the supporting structure.(2)With the help of MIDAS GTS NX geotechnical analysis software,the finite element model of the foundation pit and its supporting structure is established,the grid size effect is comprehensively considered,the appropriate size is set,and the reasonable constitutive model and its parameters are selected.Through the simulation of the construction phase,this paper dynamically analyzes and compares the deformation of the supporting structure under the two construction methods,and explores the advantages and disadvantages of the two construction methods.Based on the degree of technical difficulty of the two construction methods,and taking into account the overall construction progress and economic effect of the project,the construction plan is determined to balance the safety and economy of the supporting project.(3)Verify the correctness of the numerical model through the early monitoring data,understand the deformation of the supporting structure and surrounding buildings in each construction stage through the numerical simulation results,and verify the theoretical calculation results at the same time.The deformation trend of all kinds of supporting structures is compared and analyzed,the safety of the supporting structure is determined,and unstable factors are adjusted in time to make the structure safer.(4)Through numerical simulation analysis,it is found that the supporting structure rises upwards in the excavation engineering of the super-large deep foundation pit,which is not consistent with the structural subsidence phenomenon in the previous foundation pit construction.Through the investigation of the numerical model of the foundation pit and the use of the variable control method to explore the influence of soil parameters in engineering construction,combined with theoretical analysis and simulation,it is found that the main and secondary reasons for the uplift of the supporting structure are: According to the cause of the uplift,the scheme of controlling the uplift of the supporting structure is explored with the help of numerical simulation,and a feasible construction scheme is found to help the project alleviate the uplift.(5)Carry out on-site monitoring and summarize and analyze the survey data,compare with the numerical simulation results at the same time,calculate and analyze the data correlation,confirm the validity of the numerical simulation,and verify the rationality of the construction optimization scheme.Combined with existing data to predict future development,the protection project is proceeding smoothly.