Multi-layer control technologies for surrounding rock stability of dynamic-loading rock burst roadway

Rock burst is one of the main disasters that threaten the safe and efficient mining in Chinese coal mines. The dynamic load roadway of Yima mining area was taken as the engineering background. The field measurement, laboratory test and numerical simulation were combined to analyze the dynamic load roadway. The characteristics of impact damage and the causes of damage were proposed. The multi-level control technologies of "deep area pressure relief - shallow area strong support - roadway surface protection" of surrounding rock of dynamic pressure roadway wereput forward. The results show that the main bursting characteristics of the dynamic pressure roadway in the Yima mining area are as follows: ①The instantaneous deformation of the surrounding rock of the roadway is large; ②The floor heave of the roadway is serious;③The deformation degree is positively correlated with the source energy; ④The surrounding rock of the roadway is slowly deformed seriously before bursting failure; ⑤The bolt support system seriously failed. The main causes are concentration of high static-loading stress caused by superposition of plateau rock stress and mining stress, dynamic load disturbance formed by brittle fracture of hard roof, struct ural characteristics of "external fragile and internal brittle"of surrounding rock of roadway and unreasonable bolt supporting system. The large-diameter borehole pressure relief can reduce the degree and scope of stress concentration, reduce the magnitude of energy release during the burst failure of deep surrounding rock, increase the distance and attenuation coefficient of dynamic load propagation, slow down the disturbance of the rock vibration load on the roadway surrounding, thereby reducing the risk of surrounding rock of the roadway.The model adopts extended or full-length high-prestressed anchoring, ultra-high-strength anchor and full-section support, supplemented by metallic yieldable support to protect the roadway space, which can effectively improve the ability of resisting burst and absorbing energy of roadway surrounding.Based on the above research results，the field practice of stability control for roadway surrounding rock under dynamic load was carried out. The monitoring result showed that rock burst has not occurred in the monitoring surrounding rock, with the deformation of roadway and the forces of bolts and cables both within the allowable range, which verified the feasibility of theoretical analysis and controlling strategies.