下穿隧道对既有地铁线路及周边环境影响研究

Research on Deformation by Overlapped Tunnel Construction in Double-line Subway and Its Influence to Neighboring Buildings

随着城市地下空间的开发,隧道交叠与穿越案例越来越多,隧道下穿既有线路时往往引发交汇段地表沉降叠加,对既有线路和周边建筑物的安全产生威胁,研究其影响可以有针对性地采取预先加固措施。通过数值模拟试验方法,研究发现当新建隧道下穿既有线路时,后者的衬砌对前者起到了预先加固作用,使得下穿隧道的拱顶沉降比未穿越段较小,但上部隧道的拱顶部位沉降显著加大有必要预先加固。此外先后两次施工的扰动会增大围岩塑性区体积,导致新旧隧道的塑性破坏区相互连通,使得穿越段上方地表的沉降槽仍然表现为显著增大。

With the development of city underground space, more and more overlapping and crossing tunnels ap- pear, and the surface subsidence can be superimposed in overlapping area by the new tunnel construction, and it will have a threat to the safety of the existing lines and surrounding buildings, so, it is important to study its effects and take preemptive reinforcement measures. With the test of numerical simulation, when the new tunnels go across the existing lines, the existence of the lower part of the lining of tunnel excavation serves as an advance reinforcement, therefore the upper part of the tunnel where the vault settlement seems much larger entails corresponding advance re- inforcement. Besides, the twice construction disturbance would increase the volume of plastic zone in the surrounding rock, leading to the intereonnection of the old and the new tunnel in the plastic zone. As a result, the top surface of the settling tank still has shown significant increase.