Study On The Influence Of Subway Shield Tunneling On The Settlement Of Existing Buildings

As China's urbanization process continues to develop,the solution to traffic problems cannot be delayed.The subway is not only comfortable and fast,but also makes full use of the underground space.As an important means to alleviate urban traffic congestion and facilitate travel,it has developed rapidly in China.Therefore,the research on the influence of subway shield construction on the upper building is very practical and needs to be further in-depth.This paper takes the tunnel construction of a subway tunnel in a certain city in China as the engineering background,and establishes a three-dimensional finite element numerical model for the underground shield tunnel construction under the existing building,focusing on the analysis of the stratum construction,the construction of the pile foundation,The settlement law of the superstructure of the building has obtained some very significant research results.The main research contents of this paper are as follows:(1)Using the large-scale finite element software Midas GTS,a three-dimensional finite element numerical model of subway shield excavation without building above the construction site was established.The distribution of surface settlement during shield excavation is analyzed by numerical model calculation and compared with the empirical formula method.(2)Based on the actual engineering of the subway shield under the existing building,considering the engineering principle of the soil-tunnel structure-building pile foundation,the model of the shield below the existing building is established,and the three-dimensional numerical model is adopted.The calculation results are processed to analyze the distribution law of ground subsidence caused by the tunnel shield tunneling under the existing building construction.The safety of existing buildings is evaluated by calculating the total settlement and settlement difference of pile foundations of existing buildings.Finally,the building settlement control measures are summarized to provide theoretical guidance for practical projects.(3)Selecting the shield construction method parameters,the thickness of the segment,the elastic modulus of the segment and the excavation pressure to carry out three-factor and four-level orthogonal tests,and study the effects of these three parameters on surface settlement,building settlement and segment lining deformation.Taking the maximum settlement value of the surface as the criterion to obtain the optimal combination of three parameters and analyzing the influence of the parameters,the primary and secondary order of the influence of the three parameters on the surface settlement is obtained.(4)Introduced the basic theory of BP neural network.According to the data calculated by the three-factor four-level orthogonal experimental design scheme,the BP neural network model was established by using the MATLAB program platform to predict the maximum settlement of the surface during the shield construction process.To compare the results,the feasibility of BP neural network to predict the maximum settlement value of shield construction surface is studied.