Abstract: With the underground caverns of Dagangshan hydropower project as background, discrete element program is adopted to simulate the excavation and support processes of underground caverns cut by different geological structures. The research focuses on the effect of bolt on the deformation, stress state and damage zone of different rock structures, and the mechanism of bolt support in jointed rock mass is discussed. The results reveal that the rock bolt gradually takes effect with the relative dislocation of joints and stress adjustment of ground rock. Limited to this interaction mechanism, bolts cannot improve rock stress state effectively. Therefore, the role of bolt strengthening is to enhance the shear strength and tensile strength of joint, improve safety factor of key blocks, and prevent the blocks from collapsing. Comparison with monitoring data manifests that the discrete element model could reflect the effect of rock bolt support in practical engineering.

Key words: bolt, underground caverns, adverse geologic structure, discrete element, joint, Dagangshan hydropower station