| Nowadays,urban development is diversified,three-dimensional,high-rise and intensive.Subway is rapidly integrated into people’s life with the characteristics of high speed,large load,low consumption and high environmental protection.In the tunnel construction,surface settlement and tunnel lining deformation become the key to the safe operation of the subway.This paper takes the shield tunneling section of Xi’an Metro Line 4 from railway station to Han Yuan Dian as the research object,and analyzes the settlement data of the section settlement by mathematical statistics and least squares principle,studies the basic law of tunnel settlement,and constructs the settlement prediction model in accordance with the research area.Using the method of numerical simulation,the settlement deformation law of the railway station～Han Yuan Dian section and the seismic capacity of the tunnel are analyzed from the perspective of static and dynamics.In order to guide the design and construction of metro shield tunnel.The main research results of this paper are as follows:(1)Collect and sort out the data of the railway station of Xi’an metro line 4 to Han Yuan Dian hall combining with the general situation of the project,determine the monitoring scheme of surface subsidence and analyze the data of the measured subsidence of the section.The results show that the tunnel between the railway station and the Han Yuan Dian is mainly located in the silty clay layer with uniform soil.The shield grouting fluid fills the lining gap,and the synchronous grouting plays a normal role.The lateral settlement of the ground caused by shield tunneling is approximately normal distribution.(2)The regression analysis method was used to fit the measured settlement data of the railway station to the Han Yuan Dian area,and the feasibility of the Peck prediction formula was determined.By means of mathematical statistics and introducing settlement correction factor,the range of settlement correction factor is obtained,and the accuracy of the surface settlement prediction of the modified Peck prediction model is determined.The verification results of the Xi’an No.4 line Wu Lu Kou～Train station section show that the relative error of settlement prediction is 8.33%,the settlement prediction is significant,and the modified prediction model is more practical.(3)According to the orthogonal experimental method,the sensitivity of the key stratum parameters affecting the settlement from the railway station to Han Yuan Dian is from the largest to the smallest:Elastic Modulus,Density,Cohesion,Internal friction angle.The relative error between simulation and measured data of longitudinal and transverse section settlement of optimization model is 3.99%,the accuracy of model is reliable,and the feasibility of optimization method is remarkable.(4)Statics and Dynamics(earthquake motion)Analysis by FLAC3D Finite Element Method,found that the burial depth increases with the burial depth,the maximum settlement decreases,the maximum principal stress increases,the width of the subsidence tank increases,the influence range of subsidence expands,and the influence of earthquake on settlement change decreases.With the increase of spacing,the effect of settlement superposition decreases,the maximum subsidence decreases,and the interaction force between tunnels decreases.Therefore,in the design and construction of subway tunnels with the similar geological and engineering method in Xi’an,when the distance between the tunnels is between 17m and 23m,and the buried depth is between 18m and 24m,the surface subsidence is relatively small and the overall seismic resistance of the tunnel structure is relatively strong.However,the Optimal design of the optimal scheme also equires a combination of site environment,equipment materials and construction capabilities. |
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