Ground Deformation And The Deviation Of Pile On The Near Side Caused By Shield Construction In Soft Soil

With the continuous development of urban rail transit construction in China,shield tunneling has become the main force in the process of subway construction with the advantages of safety,efficiency and environmental protection.Due to the complexity of urban space and geography,the safety impact of metro shield tunnel near bridge construction has gradually become a hot topic in engineering practice and theoretical research.In this paper,based on the side crossing bridge pile project of Hangzhou Shaoxing inter city railway shield tunnel,the comprehensive analysis method of theoretical analysis,numerical calculation and field in-situ monitoring is used to study the mechanism of stratum deformation and the law of pile foundation displacement in the process of shield tunnel excavation.The research results are of great practical significance for improving the safety and stability of urban tunnel excavation and reducing the project risk.The main contents of this paper are as follows:(1)Based on the theoretical study of the displacement of soil and pile foundation,this paper analyzes the ground settlement law and the mechanism of pile-soil interaction in the construction of shield tunnel close to pile foundation,and gives the calculation method of the displacement of soil and pile foundation.(2)The numerical analysis method is used to simulate the construction process of the pile foundation close to the shield.The influences of the distance between the pile and the tunnel,the buried depth of the shield tunnel and the radius of the tunnel on the surface settlement and the displacement of the pile foundation are studied.The sensitivity of the maximum ground settlement and the maximum horizontal displacement of the pile foundation to the construction design factors is analyzed.The results show that the maximum ground settlement is more sensitive to the distance between the pile and the tunnel,and the buried depth of the tunnel is more sensitive It has great influence on the maximum horizontal displacement of pile foundation.The fitting curve between construction design factors and the maximum horizontal displacement of pile top is established,which can provide reference for engineering design.(3)Taking the shield tunnel of Hangzhou Shaoxing inter city railway as the engineering background,the displacement of soil layer and pile foundation in the whole process of shield construction is calculated through the simulation analysis of the finite element software.The laws of surface settlement and pile foundation displacement are summarized,and the rationality of the design is verified.(4)The rationality and correctness of the numerical calculation are verified by comparing the in-situ monitoring data of multi-point displacement meter with the settlement calculation results of construction simulation.The risk of construction can be effectively reduced by numerical simulation analysis.