| Nowadays,with the vigorous development of Metro Engineering in China,many cities begin to construct their own metro.Different cities have different geological conditions and engineering characteristics.Therefore,different engineering problems are encountered in the construction.Based on the Tianwang-Hongqing Metro Tunnel of Lintong Line of Xi’an Metro,this paper analyses and studies the dislocation of ground fissures and the underground excavation of different sections.The specific research work is as follows:(1)According to the characteristics of ground fissure dislocation in practical engineering,simulating the stratum dislocation in the upper wall,analyzing the distribution law of stress and deformation of surrounding rock and tunnel lining structure under different dislocation quantities,finding out the key control position in the construction process of tunnel according to the characteristics of ground fissure dislocation,and discussing how to resist the dislocation by increasing the lining thickness locally and enlarging the section.and a comprehensive solution to resist the displacement is proposed.(2)Using stratum structure method and combining with field measurement data,this paper analyses the influence of temporary inverted arch on the deformation,stress and surrounding rock deformation of tunnel structures at different locations,and puts forward the concept of control rate,and obtains the control rate of casting temporary inverted arch on tunnel deformation and stress.In addition,through numerical simulation,the construction step optimization of the piston duct of Hongqing Station is studied,and the similarities and differences of different multi-step excavation methods,such as 10-step,8-step and 6-step,are analyzed.Optimize construction steps and improve site construction efficiency.(3)Completely simulate the entire construction process of E section(mid-cavern excavation method)and the D section(side drift method)of the crossing section,The different effects of each part of soil excavation on surface settlement and surrounding rock plastic area are analyzed under the complex construction steps,and the corresponding supporting structure forces are obtained.Meanwhile,the related influences of different demolition support schemes on the surrounding rock and supporting structure of the left and right sections and the middle section of the mid-cavern excavation method are analyzed,and the comprehensive measures for strengthening the weak soil between the small clearance tunnels are proposed.The research results of this paper provide some technical support for the tunnel excavation in the area of ground fissure dislocation and the tunnel excavation with thin and high cross-section,the large cross-section tunnel excavated by the mid-cavern excavation method and the side drift method,and put forward concrete feasible schemes for resisting stratum dislocation,strengthening weak soil between tunnels,and dismantling temporary support,which have certain reference significance. |
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