Induced Seismicity Caused by Sudden Failure of Rock Joints with Different Undulation

Natural crustal earthquakes happen when preexisting faults have sudden movement. For induced seismicity of a low magnitude, the study of sudden failure of rock joints has more practical significance in engineering projects. Rock-like samples with five different undulations on artificial joints are tested by a split Hopkinson pressure bar (SHPB) to analyze the influence of joint undulation on dynamic failure strength and fracturing behavior. The rupture process is recorded by a high-speed camera using digital image correlation technology. Experimental results indicate that optimal undulation ranges in 50/120 to 50/140 have the maximum compressive strength and can absorb the most energy. The energy is absorbed by the concave structure rather than creating new cracks. Compressive failure tends to occur on the concave side and the concave side always has more fracture than the convex side. The degree of fragmentation decreased when the sample had higher undulation under the same impact velocity. The number of cracks and the size of broken blocks are determined by impact velocity. This research provides a beneficial attempt to understand the induced seismicity caused by a joint failure under impact load and is of great importance in mitigating anthropogenic geohazards economically and efficiently.