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基于改进刚体弹簧方法研究结构面在围岩开挖过程中的响应及围岩损伤区范围。改进刚体弹簧方法基于Voronoi网格,能够显式模拟细观裂隙的起裂、扩展和贯通过程。界面破坏准则结合了Hoek-Brown准则和抗拉强度准则,能同时考虑拉裂和剪切2种破坏模式。计算采用渐变式的网格,对重点关注区域进行网格局部加密,这种方式可以精细考虑开挖面附近的围岩损伤同时提高计算效率。为验证模型的合理性,在弹性条件下对一个简单算例进行计算,计算结果与有限元结果吻合良好。以锦屏二级水电站引水隧洞为例,计算NWW向优势陡倾节理在不同开挖步对围岩损伤区的影响,损伤区分布规律与现场观测结果基本吻合。
The response of structural plane to the excavation process of surrounding rock and the range of surrounding rock damage zone are studied based on the improved rigid body spring method. Based on the Voronoi grid, an improved rigid-body spring method can simulate the initiation, propagation and penetration of mesoscopic fractures. The interface failure criterion combines the Hoek-Brown criterion and the tensile strength criterion, and can simultaneously consider two failure modes of fracture and shear. The calculation uses a graded grid to locally mesh the key areas of interest. In this way, the damage of surrounding rock near the excavation face can be carefully considered and the computational efficiency can be improved. In order to verify the rationality of the model, a simple example is calculated under the elastic condition. The calculated results are in good agreement with the finite element results. Taking the diversion tunnel of Jinping Ⅱ Hydropower Station as an example, the influence of the dominant steep slope in NWW on the surrounding rock damage zone is calculated. The distribution of damage zone is in good agreement with the observed results.