Experimental and numerical investigations of dynamic failure process in rock under blast loading

For study the dynamic failure processes between adjacent boreholes with decoupling charge, the single-hole and double-hole blast loading experiments are set up with granitic samples. High-speed cameras (HS) and digital image correlation (DIC) methods are adopted to obtain strain field and crack development process. According to experimental results, the distribution of damage is symmetric around center hole under single-hole loading, shock wave falls off rapidly with increasing distance from the bore hole. Under double-hole loading, the damage and plastic strain are accumulated under second loading. The second loading makes the superposition of stress waves and the radial cracks formed between two holes. Meanwhile, the bimodal strain-time curve is found along vertical direction, and indicates the no damage is generated by elastic deformation is formed. According to the numerical results, the dynamic responses under two loads are agreed well with experimental results. The borehole pressure is much high when decoupling factors (K) is 1, and then linearly decreased with K increase. The horizontal cracks run through specimen as K = 2 similar to 5, and the vertical cracks linearly decrease with K increases.