Numerical Analysis of Segmented Countermeasures for Metro Tunnels Intersecting Ground Fissure Zones at Small Angles

Ground fissure is a unique geological disaster in Xi'an, China. It is stretched over 150km ² . Severe damages to infrastructures and facilities are encountered in reality due to the dislocation from ground fissure. When web-distributed metro lines are constructed, the tunnel lining will be inevitable undermined. In this paper, the engineering practice of Xi'an Metro Line 3 intersecting ground fissure zones at small angles has been evaluated. Numerical methods were used to study two setting schemes of deformation joints and the effect of ground fissures on the service performance of tunnel lining. The results show that the riding-type scheme reduces the range of axial tension on tunnel lining to a certain extent. The ground fissures in the jointing-type scheme significantly influence the tunnel lining located in the hanging wall, and the axial tension on tunnel lining appears only in the location closer to the hanging wall. When the tunnel intersects the ground fissure section at small angles, it is better to employ the jointing-type of joints-setting scheme.