The current indexes for rock-burst tendency assessment neglect either the pre-failure or post-failure stages of the rock mass. This paper proposes a new Stress–Brittleness–Energy index, denoted as the SBE, which incorporates in situ stress conditions as well as the characteristics from both the pre-failure and post-failure stages of the rock mass into a rock-burst tendency evaluation system. The SBE index is based on both the strength and energy characteristics of deep rock masses under true triaxial stress conditions, making it particularly suitable for assessing rock-burst tendency in hard rock tunnels within true triaxial stress conditions. The index was implemented in a self-developed numerical code CASRock and applied to three actual rock-burst cases (including the Mine-by test tunnel and the Jingping II headrace tunnel #4), which validated its effectiveness at the engineering scale. Subsequently, laboratory-scale model tests of rock-bursts induced in circular hard rock tunnels with two different diameters were conducted, further verifying the effectiveness of the SBE index for assessing rock-burst tendency at the laboratory scale. Finally, the SBE index was employed to predict the rock-burst tendency of a tunnel under construction in West China. The predicted pit depth, rock-burst level, location, and range using the SBE index provided a reliable basis for designing the support system and controlling the tunnel advance rate.
Zheng et al. (Thu,) studied this question.