Failure mechanism of anchored bolt supporting structure of circular roadway under dynamic load

By reasonably simplifying the stress wave, a simplified model for the reciprocity between the plane p-wave and the circular anchoring roadway is built. Based on a typical case, through analyzing such remarkable parameters as radial stress of deep surrounding rock, tangential stress of roadway surface, radial displacement of roadway surface and radial displacement difference between deep surrounding rock and roadway surface, the strategic locations of support are confirmed, the force mechanism of bolt is deduced, and the corresponding failure patterns and failure criteria are put forward. The results show that the side facing the stress wave and the lateral position are the strategic locations of support. It is found that: (1) The total stress of bolt on the side facing the stress wave is the superposition of static axial stress, dynamic stress of bolt vibration and subsidiary stress caused by the surrounding rock deformation under dynamic load. Under the strong impact, a single instantly destroyed destruction will occur, the surrounding rock is pressed to fracture and the loose bolts lose the reinforcement. Under the cyclic weak impact, the pressed surrounding rock is gradually damaged to fracture, and that the bolt is loose owing to being pressed and straightened repeatedly intensifies the fracture of the surrounding rock further. When the strength of the load-bearing arch is decreased to a certain value, a weak impact can induce the burst failure of roadway; and (2) The total stress of the bolt at the lateral position is the composition of the static axial stress and the subsidiary stress caused by the surrounding rock deformation under the dynamic load. The bolt here is being subjected to tension, so tensile failure will occur under the strong impact. The results of similar simulation experiments are consistent with the theoretical ones, indicating that the theoretical analysis can be a significant guidance for engineering practice.