Abstract:

For the Xi’an metro line No.2 passing through ground fissure active zones, the interaction mechanism between lining and surrounding rock was studied by the physical model test, stimulating the metro tunnel orthogonally crossing the ground fissure and being consistent with the settlement crack of lining structure, with geometrical proportion of 50:1. Test results show that the regularity of wall rock pressure, stress and uneven settlement of lining structure changing with the relatively vertical deformation are similar under the different stress fields for the case of the settlement crack being consistent with the orthogonal ground fissure in strata. The relative settlement between two sections of lining structure with deformation crack at ground fissure develops apparently with the relatively vertical displacement between upper strata above ground fissure and lower strata below ground fissure. The lining structure is of large settlement in the upper strata and small settlement in the lower strata. The additional stress of lining structure and increasing value of earth pressure acting on lining structure is small in the upper strata and large in the lower strata. The maximum value of additional stress and earth pressure locates at the section closing to the ground fissure. When the ground fissure being of largely vertical displacement, the wall rock pressure on the bottom of lining structure in the upper strata decreases obviously or equals to zero. It could point out that the research of physical model experiment has importantly theoretical and practical significance to the construction of underground engineering and maintenance operation in the area of ground fissure.

Key words: ground fissure, metro tunnel, model experiment