Analysis Of The Effects Of Hefei Subway Shield Tunneling On Surface And Buildings

Today, urban rail construction in China is developing rapidly, shield method has become the main method of subway tunnel construction. Shield method has its obvious advantages compared to other methods, but it still will inevitably cause disturbance to the surrounding soils, thereby affecting the safety of buildings. Therefore, studying influence mechanism of surface and buildings caused by shield tunneling, then put forward practical control measures has important significance.Taking Hefei Metro Line one Great East Gate Station-Wuhu Road Station shield zone as engineering background, through analyzing the data of several typical surface subsidence monitoring sections and a building, the paper concludes surface subsidence law and building settlement rule during the excavation of tunnel. It results that ground subsidence mainly occurs after the end of the shield via shield prolapse stage, lateral surface subsidence is in line with the law of settling tank.The paper also uses numerical analysis software MIDAS/GTS to establish a three-dimensional numerical model of the tunnel through a five-story building of masonry structure and study the influence law of tunnel buried depth, tail shield grouting, driving pressure and different excavation sequence of double line tunnels on surface subsidence. The paper analyzes the settlement rule of surface and buildings during excavation,and makes evaluation on the safety of buildings.lt results that after left tunnel first excavation, the surface horizontal sedimentation tank of left and right sides are symmetrical, after excavation of the right tunnel, soil of the left tunnel has been disturbed secondrily,causing additive effect on surface settlement of left tunnel, the maximum surface subsidence is just above the centre line of left tunnel, differential settlement and stress of building are both small,the building is in a safe state.In addition,the paper compares and analyzes the simulation results and monitoring data, there is little difference between them and the trend is a better fit,which can provide reference for the construction. Finally, construction control measures of surface and buildings are put forward based on the actual project.