Experimental study on preventing slippage failure of resin bolt in coal roadway by backfilling with enlarged bottom

This paper adopts numerical simulation to study the displacement and stress distribution states of each component of the bottom-expanding filling anchorage system, and analyzes the change of controlling roadway deformation and improving anchorage capacity of backfilling anchorage of bottom-expanding filling system compared with normal anchorage by combining with field tests. Numerical simulation results show that the larger the maximum diameter of reaming is, the greater the axial stabilizing force is and the more stable the anchoring system is. Taking the axial load of 150 kN as an example, the maximum stress value of the borehole surrounding rock is 2.9 times that of the normal anchorage when the bottom is enlarged and the anchorage is filled. The maximum stress value of anchoring agent is 2.8 times that of normal anchoring during filling anchorage with bottom expansion. The deformation of surrounding rock and anchoring agent is less than that of normal anchoring. The displacement variation of each part is basically the same for more than five times of filling and anchoring, it is concluded that the five-fold expansion of the bottom is the most feasible. The results of field test show that the total amount of roof deformation and the deformation rate are smaller than the normal support. The anchoring capacity of the anchoring system increased by 2.1 times.