Study On Influence Of Shield Construction On Surrounding Buildings In Complex Stratum

Shield construction has become the main method for the construction of urban tunnels.The earth pressure balance shield is widely used in soft formations because of its good applicability and economy.During the earth pressure balance shield tunnelling,the surrounding soil and buildings will be settling,affecting their normal use and even endangering personal safety.They will be more prominent under complex or weak geological conditions.Therefore,it is of great significance to guiding the construction of subway tunnels to study the sinking law of ground surface and buildings of earth pressure balance shield in tunneling in soft groundThis paper summarizes the current research status and achievements of surface settlement and building settlement caused by shield construction.Based on the working principle of earth pressure balance shield,the theory of Peck is adopted to discuss and analyze the general laws of ground settlement and building settlement.The analytical method of theory is adopted to calculate the engineering example of the shield passing through the adjacent frame structure construction.Second,by comparing the monitoring data of the Huaxian and Denghua ranges of Foshan Rail Transit Line 2 with the Peck formula and fitting the Gauss formula with the settling data of multiple sections of the Huaxian area,the range of the value of the formation loss rate is obtained to provides the basis for the selection of finite element simulation parameters.The building settlement data is presented in the form of a scatter plot,and the general rule of building settlement is obtained.Plaxis software is used to numerically simulate the shield excavation process,and the ground settlement of the shield during the tunneling period is analyzed,which is compared with the actual monitoring data and Peck theoretical calculations.The relations of the law of settlement change of the tunnel centerline sections and the longitudinal surface settlement of tunnel and tunnel depth was analyzed.Controlled variables method was used to study the effect of thick soil cover,grouting pressure,stratum loss rate and soil parameters on lateral ground settlement.Plaxis software is used to simulate the process of shield excavation on buildings.The study focused on the settlement rule of shield tunneling,the influence of additional foundation stress on foundation settlement,and the settlement difference between column foundations under conditions of shallow bases.At the same time,the settlement,horizontal displacement and internal force change of pile foundations at different positions during shield excavation are discussed.The simulation results are compared with on-site monitoring data to verify the feasibility of numerical simulation in related researches.