Impact of voids and backfill on seismic wave velocity-preliminary results

Abstract In this study, laboratory experiments were conducted on discrete physical models that mimic mining effects to better understand the impact of continuous changes in mining environments on seismic wave velocities. The discrete physical models are represented by concrete and granite cubic samples of different sizes with holes of different diameters filled and unfilled with cemented sand backfill of different cement-sand content ratios. The hole diameters range from 0 to 150 mm in block sizes ranging from 150 mm to 450 mm in increments of 75 mm. The increasing hole size mimics increasing extraction in the mine with time. Cemented sand fills at cement contents ranging from 0 to 20% are used to fill the voids after testing them empty and retesting the same at different backfill cured ages. The SAEU3H AE eight-channel system is used in the study. Preliminarily results show that the impact of continuous changes in mining environments significantly affects the seismic wave velocities. The impact of voids and their contents on the seismic wave velocity depends on the sensor location relative to source and void, and it backfills cement content with time.