Research On The Law And Control Of Ground Settlement Of Metro Tunnel Under The Combined Construction Of CRD Method And Bench Method

With the rapid development of China ’s economy,the process of urbanization is also accelerating.More and more people are flocking to big cities,resulting in increasing urban pressure.In order to alleviate urban traffic pressure,more and more cities are joining the wave of subway construction.In the process of subway construction,it is inevitable to disturb the original rock strata,resulting in surface movement and deformation.Therefore,it is of great significance to study the influence of shallow tunnel excavation on surface subsidence and its control analysis to reduce the harm caused by tunnel constructionThis paper takes the shallow-buried and under-excavated section of Wangjing West Station to Yongshiying Station of Beijing Metro as an example,and carries out numerical simulation calculation with the help of finite element software ABAQUS.The specific research work and results are as follows:(1)According to the research data at home and abroad,the theory of surrounding rock pressure,the law of longitudinal surface settlement and the simplified formula of transverse settlement of random medium theory are expounded.(2)Based on the engineering background,a numerical model is established.The comparison between the simulation data and the monitoring data shows that the settlement law and the maximum settlement of the surface and vault are basically consistent,and the difference is small,indicating the reliability of the numerical simulation.(3)In the software simulation,by changing the order of the construction method conversion,the stiffness of the construction method conversion,the excavation footage,the excavation method and the grouting thickness,the influence of the combined construction of different tunnel construction methods on the surface settlement is studied.From the order and stiffness of the method conversion: although the order and stiffness of the method conversion can reduce the surface settlement to a certain extent,it has little effect on the surface settlement;from the aspect of excavation footage: the surface settlement decreases with the decrease of excavation footage,and it is more effective to reduce the excavation footage in the CRD stage than in the step method stage.From the aspect of excavation method : changing the construction sequence of CRD has little effect on the surface settlement,the double side drift method causes the smallest surface settlement,and the step method causes the largest settlement;from the aspect of grouting thickness : the thickness of grouting has a significant impact on the surface settlement.Without grouting reinforcement on the excavation surface,the grouting reinforcement on the excavation surface is expanded by 0m,the surface settlement value of the tunnel is far more than the standard value,and the grouting range of the excavation surface is increased from 1.5m to 4.5m,which can not effectively reduce the surface settlement,but lead to the waste of materials.Figure [65] table [8] reference [51]...