Effects of fractures on seismic wave propagation path: laboratory studies

In this study, discrete physical models using different blocks and hole sizes, and backfill characteristics are used to simulate changing underground mine conditions due to mining activities. In addition to voids and various backfills, this study includes fractures to investigate their effect on seismic wave propagation. The fracture systems in concrete blocks with sizes of 150 mm, 225 mm, 300 mm, 375 mm, and 450 mm were created by filling holes of various diameters in the concrete cubes with a static cracking agent (SCA). This process mimicked blast and stress-induced fracturing in the underground mine environment. AE measurements indicate that AE signal attenuation from fractures is more severe than due to backfill and in presence of fractures, backfill did not create a favorable environment for AE wave propagation toward receivers. AE signal arrival time to receivers mainly depends on the direction of AE wave propagation rather than the geometrical arrangement of the sensors in the presence of the voids, backfills, and fractures. AE signal arrivals to receivers are governed by the subsurface variability, Snell's law, and AE wave propagation direction. These factors should be considered to enhance the current source location approaches in microseismic monitoring systems..