Weakening effects of the presence of water on the brittleness of hard sandstone

The weakening effects of increasing the water content in rocks have been studied extensively in a wide variety of rock types over the past few decades. High energy release is typically characteristic of rock burst hazards. However, few studies have investigated the mechanism of water involved in rock bursts from the perspective of energy distribution based on the water content. Therefore, in this study we investigated the evolution of microcracks in hard sandstone determined from triaxial tests combined with an acoustic emission analysis for different water contents and confining pressures. Then, the weakening effects of water on the brittleness of the rock were studied from an energy viewpoint. The study shows that the capacity of the storage energy of hard rock decreases due to the dissipation of internal elastic energy in the compression stage in the presence of water. These results revealed the mechanical and energetic mechanisms that caused the weakening effects induced by water on rock burst and can contribute to design and construction improvements in tunnel engineering.