Experimental investigation on effect of loading rate on fracture behavior of coal-seam roof rock

The fracture behavior of coal-seam roof rock in coal mining is a key and controlling factor for the mode optimization artificial caving. However, mechanism under loading not clear. In work, split Hopkinson pressure bar (SHPB) experiment was carried out using semicircular bending samples from sandstone Junger area Inner Mongolia at rate 0.35–3.78 GPa·m 0.5 ·s −1 , dynamic energy dissipation different rates were investigated. result shows that stress–strain process hard includes four stages: linear instantaneous compaction, elastic compression, failure, extension, which failure forms changes brittle to ductile with increase rate. I toughness increases linearly confining pressure. addition, propagation orientation induced fractures parallel direction, gravel can inhibit resulting changing extension path. Further, absorption efficiency during decreases