Metro tunnel hazards induced by active ground fissures in Xi’an and relevant control measures

The ground fissures in Xi’an are one of the particular urban geological hazards and have a serious threat on Xi’an metro construction,so it is the key for Xi’an metro construction to solve the problem of active ground fissures.On the background of Xi’an metro transversing the active ground fissure zones,the metro tunnel hazards induced by active ground fissures are analyzed based on the characteristics of ground fissures and their moving trend.The control measures are put forward from the following aspects: structural measures such as the enlarged cross-section,local reinforced lining,segmented tunnel lining and flexible joints;waterproof measures including the detachable segment method and a new flexible anti-cracking sealing strip made of fortified corrugated plate rubber complex material;foundation injected reinforcement and method of foundation deformation recovery of elastic sack;establishment of warning programs of the deformation of tunnel lining and metro track;design of the strike of metro line perpendicular with ground fissure zones or intersecting with large angle;and prohibition of groundwater withdrawal within a certain scope along the metro.The conclusions can be presented as the reference for the structural and waterproof design of metro tunnel going through the active ground fissure zones.