Experimental study on the effect and weakening mechanism of water on impact-induced rockburst
LIU Dongqiao1，SUN Jie1，2，CAO Binghao1，2，HE Manchao1，ZHANG Ziqian1，2，PENG Dong1，2
(1. State Key Laboratory for Geomechanics and Deep Underground Engineering，China University of Mining and Technology，
Beijing 100083，China；2. School of Mechanics and Civil Engineering，China University of Mining and Technology，
Beijing 100083，China)
Abstract To investigate the weakening mechanism of water on impact-induced rockburst，15 experiments were performed considering different water content levels on cubic sandstones. Photography and acoustic emission (AE) system were used to monitor the rockburst process. According to the photography results，impact-induced rockburst under different water content levels all experience three processes：particle ejection，debris peeling，and comprehensive rockburst. In addition，the results also show that the higher the water content level，the lower the intensity of the rockburst. This effect is reflected in the fact that the AE energy，the quality and the fractal dimension of fragment show a decreased trend with the increase in the water content level. Based on the perspective of energy and micro-crack evolution，two mechanisms are proposed to explain the weaking effects of water on rockburst intensity，including：(i) water increases the plastic deformation capacity，weakens the energy storing capacity and reduces the rockburst tendency of sandstone，resulting in a slightly intensity of rockburst；(ii) water accelerates the expansion of shear cracks，which is not conducive to the occurrence of plate cracking before rockburst，and destroys the conditions for rockburst inoculation.
