Numerical Simulation And Optimization Analysis Of Pile-Anchor Support Structure For Deep Foundation Pit Based On MIDAS/GTS

With the development of foundation pit to deeper and wider,the research of experts and scholars on foundation pit support structure has gradually changed from strength control to deformation control.Among many foundation pit supporting structures,pile-anchored supporting structure has become one of the most commonly used supporting forms due to its low cost,convenient construction and good supporting effect.However,there are still some problems in the research of pile-anchored support structure,such as the selection and optimization of the design parameters of pile-anchored support structure need to be further discussed and solved.In view of the problems in the pile-anchored support structure mentioned above,this paper takes a deep foundation pit support project in Handan as the background,and according to the surrounding environment and geological conditions,uses MIDAS/GTS to establish a numerical model to simulate the excavation of the foundation pit.At the same time,the field monitoring data were sorted out and the monitoring results were compared with the numerical simulation results to verify the rationality of the numerical model in the foundation pit support project.By changing the values of four soil parameters,such as elastic modulus,cohesion,internal friction Angle and Poisson ratio,the models were established respectively,and the influence of four soil parameters on the deformation of pile-anchor support structure was compared and analyzed.Finally,the influence of five parameters on foundation pit deformation was studied and analyzed,including row pile diameter,row pile spacing,anchor cable prestress,anchor cable inclination Angle and anchor cable length,and these parameters were optimized and analyzed by orthogonal test,and the optimal support scheme of this foundation pit was found.The main contents of this paper are as follows:(1)By referring to relevant literatures,several function models of earth pressure without reaching the limit equilibrium state are summarized,and their advantages and disadvantages are analyzed;This paper briefly introduces three calculation methods of deformation of pile-anchored support structure.(2)Sorting out the field monitoring data,and analyzing the variation law of the horizontal displacement of the crown beam top and the horizontal displacement of thesupport pile along the depth direction;MIDAS/GTS software was used to create a numerical model to simulate the excavation process of the foundation pit,and the rationality of the numerical model in the foundation pit was verified by comparing the field monitoring results with the numerical simulation results.The influence of elastic modulus,cohesion,internal friction Angle and Poisson ratio on the deformation of pile-anchored support structure was analyzed.(3)By changing the supporting pile parameters(pile diameter,pile spacing)and anchor cable parameters(anchor cable prestress,anchor cable inclination Angle,anchor cable length)of the model,the deformation characteristics of the foundation pit were analyzed and studied,and the orthogonal test method was used to optimize and analyze the above parameters to find the optimal scheme for this project.