关键词: 大连地铁, 浅埋大跨隧道, 双层初期支护, 现场监测, 数值模拟, 刚度比

Abstract:

There have been few shallowburied Metro tunnels with doublelayer primary support. Therefore, there is little experience in the selection of combination mode and thickness of the doublelayer support. In this paper, the influence of the combination mode and stiffness ratio of doublelayer support on the surrounding rock pressure and ground surface settlement is studied by means of field monitoring and numerical simulation, with Xinggongjie Station tunnel on No. 2 Line of Dalian Metro as an example. The study shows that: 1) Of the three combination modes including “double lattice girder layers”, “outerlayer shaped steel+innerlayer lattice girder” and “outerlayer lattice girder+innerlayer shaped steel”, the combination mode of “outerlayer lattice girder+innerlayer shaped steel” is most suitbale to Xinggongjie Station tunnel, and the rational outerlayer support thickness is 35 cm and the rational innerlayer support thickness is 20 cm; 2) The outerlayer primary support is the main loadbearing structure, and the surrounding rock pressure born by the outerlayer support increases as the ratio of the stiffness of the outerlayer support to that of the innerlayer support increases; The innerlayer primary support is the secondary loadbearing structure, and the surrounding rock pressure born by the innerlayer support reduces as the ratio of the stiffness of the outerlayer support to that of the innerlayer support increases. 

Key words: Dalian Metro, shallowburied largespan tunnel, doublelayer primary support, field monitoring, numerical simulation, stiffness ratio