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围岩板裂化是深埋高地应力条件下硬脆性围岩开挖后出现的一种典型破坏形式。影响围岩板裂化形态和形成机制的因素很多,开挖断面的曲率半径是其中的关键因素之一。为了研究开挖断面曲率半径对深部硬脆性围岩板裂化的影响,首先总结、分析了锦屏二级水电站深埋隧洞不同开挖断面曲率半径所对应的板裂化形态和特征。在此基础上,设计了室内物理模型试验,研究不同孔径的圆形洞室和不同尺寸的直墙拱洞室在平面应变条件下的板裂化破坏形态。研究结果表明,开挖断面的曲率半径对围岩板裂化的影响机制表现在尺度效应和结构效应两个方面,影响着板裂化的破坏形态和破裂机制,当同一洞室断面包含不同曲率半径段时,板裂化破坏表现出曲率半径影响下的组合破坏特征。最后,利用数值模拟结果分析和验证了开挖断面曲率半径对围岩板裂化的影响效应。
Surrounding rock slab cracking is a typical failure mode after hard and brittle surrounding rock excavation under deep ground stress. There are many factors that influence the cracking shape and formation mechanism of the surrounding rock. One of the key factors is the radius of curvature of the excavation section. In order to study the influence of the radius of curvature of excavation section on the cracking of deep hard and brittle surrounding rock, the shape and characteristics of the plate cracking corresponding to the radii of curvature of deep excavation in Jinping Hydropower Station are analyzed. On this basis, the indoor physical model test was designed to study the plate cracking failure modes of circular caverns of different diameters and different sizes of straight-walled arch caverns under the plane strain condition. The results show that the influence of the radius of curvature of excavation section on the cracking of surrounding rock is manifested in two aspects: the scale effect and the structural effect, which affect the failure mode and the rupture mechanism. When the same cavern section contains different radius of curvature , The failure of plate cracking shows the combined failure characteristics under the influence of the radius of curvature. Finally, the numerical simulation results are used to analyze and verify the effect of the radius of curvature of the excavation section on the cracking of surrounding rock.