Roof-cutting and energy-absorbing method for dynamic disaster control in deep coal mine

Deep mining roadways are often under high-stress conditions and strong mining-induced disturbances. In the traditional longwall mining method, stress concentration and energy accumulation take place in the surrounding rock of the roadway, often causing dynamic disasters. To this end, the roof-cutting and energy-absorbing (RCEA) control method is proposed. Directional roof presplitting is used to transfer the roof stress and release the energy accumulated in the rock. Importantly, a roadway is automatically formed and coal pillars are eliminated. Moreover, new constant resistance energy-absorbing bolt and cable with high prestress and high elongation are used to control the roadway roof, which are independently developed. As a result, the self-supporting capacity of the rock is improved, and the energy released by the rock deformation is effectively absorbed by the support system. To verify the fidelity of the RCEA method, the numerical comparison test between the automatically formed roadway (AFR) method and the gob side entry driving method is carried out. Compared with the latter, the energy per unit length of AFR is reduced by 4.59*10(6) J, and the maximum energy density is reduced by 36.6%, which shows that AFR has profound effect on the energy release. Subsequently, the mechanical tests on the new bolt (cable) are carried out. The forces at fracture of the new bolt and cable are 1.63 times and 2.80 times that of the common bolt, and the maximum energy absorbed per unit length are 3.05 times and 2.89 times that of the common bolt. The new bolt (cable) has characteristics of high strength and high energy absorption. Finally, the strength-energy combined support design method and the field application are carried out. Field monitoring results show that the RCEA method can effectively release the energy accumulated in the rock and ensure the safety and stability of the roadway.