An Experimental Investigation into the Strainburst Process Under Quasi-static Loading

Abstract

Rockbursts cause damage to underground excavations in a sudden and violent manner and are associated with mining-induced seismic events. We propose a simple experimental method to study strainburst process in the laboratory, that simply involves a common compression testing apparatus and rock-coal-rock specimens. Strainbursts of coal samples are successfully produced and the burst process is monitored using high-speed camera and acoustic emission sensors. The strainburst mechanism is characterized by an initial ejection of small coal fragments followed by the ejection of large coal blocks. We found that the strainbursts are caused by the elastic strain energy stored in the rock samples during the uniaxial compression. The amount of the transferred energy is significantly less than the elastic energy stored in the coal sample but plays an important role in triggering strainbursts. The greater the transferred energy, the greater the damage severity of strainbursts occurred in the coal sample. Tensile cracking subparallel to the vertical loading direction and tangential compressive stress appears to play a dominant role in the strainburst failure mechanism.