Physical model test and numerical simulation on the failure mechanism of the roadway in layered soft rocks

Abstract

To explore the failure mechanism of roadway in layered soft rocks, a physical model with the physically finite elemental slab assemblage (PFESA) method was established. Infrared thermography and a video camera were employed to capture thermal responses and deformation. The model results showed that layered soft roadway suffered from large deformation. A three-dimensional distinct element code (3DEC) model with tetrahedral blocks was built to capture the characteristics of roadway deformation, stress, and cracks. The results showed two failure patterns, layer bending fracture and layer slipping after excavation. The layer bending fracture occurred at positions where the normal direction of layers pointed to the inside of the roadway and the layer slipping occurred in the ribs. Six schemes were proposed to investigate the effects of layered soft rocks. The results showed that the deformation of ribs was obviously larger than that of the roof and floor when the roadway passed through three types of strata. When the roadway was completely in a coal seam, the change of deformation in ribs was not obvious, while the deformation in the roof and floor increased obviously. These results can provide guidance for excavation and support design of roadways in layered soft rocks.