Experimental study on characteristics of stress wave propagation in mesoscale and complex rock mass by microseismic monitoring

By using the digital multi-channel microseismic monitoring system, the characteristics of blast stress wave propagation in deep complex and mined-out area and upper fractured rock mass are tested. The wave velocity is acquired by the curve fitting method, which uses the P wave triggering time and propagation distance. The results show that the wave velocities in deep complex and mined-out rock mass and upper coagula rock mass are obviously different. Fitted the curve by using the stress wave amplitude and propagation distance, it is found that the stress wave amplitude decreases in the form of power when the propagation distance increases. By using the signal spectrum analysis and filtering, the attenuation coefficient and frequency are in cubic polynomial relations, and the attenuation of the high-frequency wave is more obvious. The average quality factors in deep complex and mined-out area and upper fractured rock mass, are calculated and they are 4.055 and 2.478, far less than those of the original rock mass, indicating that the mined-out area and fracture have great influence on the stress wave propagation.