关键词: 硬脆性围岩, 高应力, 板裂化破坏, 曲率半径, 影响机制

Abstract: Generally, slabbing is the typical failure mode when the hard brittle rockmass in deep tunnel is excavated under the condition of high stress. Many factors are contributed to the form and formation mechanism of slabbing, in particular the curvature radius of the excavated section. Therefore, the influence of curvature radius on the hard brittle slabbing is firstly summarized and analyzed the slabbing form and feature corresponding to curvature radius of different sections in deep tunnel of Jinping II hydropower station. Subsequently, the indoor physical model test is designed to investigate the slabbing forms of circular caves with different bore diameters and straight-wall arch caves with different sizes under plane strain condition. The results show that the slabbing mechanisms influenced by the curvature radius can be demonstrated at both scale and structural effects, which jointly affect fracture morphology and fracture mechanism of slabbing. When the sections in the same tunnel consist of different curvature radii, slabbing failure presents combinated characteristics of fracture. Finally, the mechanisms of slabbing influenced by curvature radius are analyzed and verified by numerical simulation.

Key words: hard brittle rockmass, high stress, slabbing failure, curvature radius, influence mechanism