盾构下穿施工对既有隧道变形影响模拟研究

Simulation study on the impacts of shield underpass constructionon the deformation of existing tunnel

随着城市地下空间的不断开发利用,地铁隧道线路网不断完善,新旧隧道交错而过的现象愈发增多。近距离盾构下穿施工可能会对既有隧道造成一系列不利影响。因此,为研究近距离隧道下穿施工对既有隧道的影响,以南宁某工程为例,通过数值模拟研究了新建隧道盾构下穿施工过程对既有隧道的变形规律影响。模拟结果表明:盾构下穿隧道施工引起既有隧道的变形以沉降变形为主,扭转变形为辅;随着新建隧道的不断推进,临近既有隧道6 m范围内沉降变化率最大,此时既有隧道最为危险,风险系数最大;新建隧道盾构施工穿越既有隧道后,由于时空效应既有隧道沉降会继续发育,直至达到最大沉降值13.0 mm;穿越过程中既有隧道扭转变形量先增大后减小,最后趋于稳定。

With the continuous development and utilization of urban underground space,the subway tunnel line network is constantly being improved,and the phenomenon of intersecting old and new tunnels is increasing.Therefore,this study aims to investigate the impact of new tunnel underpass construction on the deformation characteristics of existing tunnels through numerical simulation.Taking a project in Nanning as an example,the simulation results show that the deformation of the existing tunnel caused by the shield tunnel construction is mainly settlement and torsional deformation.As the new tunnel continues to advance,the settlement within 6m of the adjacent existing tunnel changes the fastest,and the existing tunnel safety risk is the greatest at this time.After the new tunnel crosses the existing tunnel,the existing tunnel settlement will continue to develop due to spatial and temporal effects until it reaches the maximum settlement value of 13.0 mm.The torsional deformation of the existing tunnel first increases and then decreases during the crossing,and finally stabilizes.