裂隙性坚硬隧道围岩的岩爆机理及强度模型研究

Rockburst, as the main geological disaster during the excavation of hard and brittle tunnel surrounding rock in the high ground stress region, seriously hindered the construction of deep underground engineering in the area of transportation and water conservancy and hydropower. The rockburst occurred in the cracked and hard surrounding rock was ignored which resulted in serious losses since the structural planes in rock were treated as a kind of well energy dissipation medium for a long period. Therefore, this research will aim at the phenomenon that rockburst occurred in the cracked and hard surrounding rock around high ground stress during the excavation of deep underground engineering. On the bases of the fracture mechanism of cracked rock and the rockburst mechanism in intact and structural tunnel surrounding conducted by predecessors, field survey, laboratory tests, theoretical analysis and numerical simulation, as well as the fracture mechanism and micromechanics of composites will be combined. The geometrical and mechanical characteristics of cracks, mechanical properties and stress condition of surrounding rock and the effect of excavation unloading will be considered. In the view of the mechanism of interaction fractured cracks and the accumulation and dissipation of energy, the rockburst criterion and intensity model of cracked and hard surrounding rock will be established. It will be used in the prediction and risk assessment of practical projects. Meanwhile, the potential presplitting will be proposed to reduce the risk of rockburst. The results can improve the construction level of deep underground engineering and reduce the risk. Moreover, it can further enrich the means of disaster prevention and reduction, which have great value for the theoretical research and practical application.

岩爆是高地应力下坚硬脆性隧道围岩开挖过程中遇到的主要地质灾害，严重阻碍了是我国西南地区交通和水利水电工程深埋地下工程的建设。长期以来，由于岩体内发育的结构面被认为是良好的耗能介质，裂隙性坚硬隧道围岩的岩爆也因此被忽视，从而在实际工程中造成重大的损失。为此，本课题将针对高地应力环境下深部地下工程开挖过程中裂隙发育坚硬脆性隧道围岩的岩爆现象，在前人对裂隙岩石破裂机理及完整和结构性隧道围岩岩爆机理研究的基础上，综合采用现场调研、室内试验、理论分析和数值模拟的方法，基于断裂力学和复合材料细观力学理论，考虑围岩内裂隙发育的几何及力学特性、围岩基本力学性能、围岩应力状态及开挖卸荷作用等因素，建立裂隙性坚硬隧道围岩岩爆判定准则及其强度模型，用于实际工程中岩爆灾害的预测及风险评估，完善岩爆减灾的预裂技术。本课题研究成果将提高我国深埋地下工程建设水平，丰富施工防灾减灾手段，具有重要的理论与实际应用价值。

随着我国西部大开发及西南地区水电开发，西部复杂地质环境下大量隧道在开挖过程中出现岩爆病害，与传统认为的完整坚硬围岩岩爆不同，随机裂隙发育的围岩同样产生强烈岩爆，造成重大损失。本课题依托西部地区水电引水隧洞和交通隧道工程，在现场调查的基础上，结合室内随机发育裂隙性岩石破裂过程试验、结构性隧道围岩模型试验、离散元数值模拟等手段，获得裂隙发育岩石的破裂特征及能量耗散规律，基于断裂力学的能量观点，建立断裂能的边界效应模型，进一步分析裂隙性隧道围岩在高应力条件下的动态破裂特征，揭示裂隙性隧道围岩岩爆机理，并提出联合初支措施，为我国深埋地下工程建设过程中岩爆灾害防治提供参考。