深部断层活化规律与洞室群稳定性和环境安全性评价

The deep tunnel groups of Jinping II hydropower station and Jinping Deep Dark Matter Underground Laboratory are at present the largest underground cavern groups in the world, characterized by the highest geostress with respect to difficult geological conditions. The deep fault activation, cavern group stability and environmental safety are the key in the construction and long-term safe operation of the project. Focusing on this issue, the faults, surrounding rocks and radon are coupled and treated as a coordinated evolutionary ‘Trinity’ system. The strategy of ‘Decomposition-Coupling-Collaboration’ concept was proposed in the study. For this, indoor tests, large-scale model tests, numerical simulations, on-site monitoring, and geological surveys will be taken into consideration in this work. The mechanism of fault activation, the release and migration mechanism of radon gas under the coupling effects of static and dynamic stresses, and the coupling mechanism of deformation and fracture evolution of surrounding rocks and faults will be revealed in this context. A deep fault activation monitoring technology system and a fluid-solid coupling numerical technology system for deep caverns group are developed subsequently, in consideration of co-evolution of fault-surrounding rock mass and radon gas. Next, an integrated evaluation method for stability and environmental safety of multi-level caverns with multi-source information will be presented. This will be conducted in combination with numerical results, on-site monitoring and dynamic feedback. The calibrated results could provide helpful information, reliable theoretical proofs and technical supporting for ensuring the long-term safety of deep underground laboratories and deep hydraulic tunnels in Jinping. The results can also facilitate the design, construction, and operation of related deep projects under similar conditions.

锦屏二级水电站深埋隧洞群和极深暗物质地下实验室是世界上埋深最大、规模最大、地应力最高的洞室群工程，深部断层活化及洞室群稳定性和环境安全性是该工程建设与长期安全运行中的关键难题。围绕该问题，将“断层-围岩-氡”作为一个耦联协同响应的“三位一体”耦联系统，采用“分解—耦联—协同”的总体研究策略，通过室内试验、大型模型试验、数值模拟、现场监测、地质勘察等综合手段开展系统研究，揭示动静力耦合作用下断层活化机制、氡的释放与迁移机制、围岩变形破裂演化与断层及氡的耦联机制，构建深部断层活化监测技术体系、深部洞室群断层-围岩-氡协同演化流固耦合数值模拟技术体系，提出基于数值计算、现场监测与动态反馈分析相结合的多元信息多层次洞室群稳定性与环境安全性综合评价方法。研究成果可为确保锦屏极深地下实验室与深部水工隧洞群的长期安全性提供可靠的理论与技术支撑，为相关深部工程设计与建设中相关问题的解决奠定坚实基础。

针对深部工程中断层活化机制及致灾机理、地质体内氡释放-迁移机制和断层-围岩-氡协同响应机制不清等难题，项目组在基础理论及技术创新方面开展了大量探索性工作和系统深入地研究，总体上达到了预期目标。研究取得了如下代表性成果：.（1）开展了系统的深部断层摩擦滑动试验，揭示了动静力耦合作用下深部断层活化模式与机制，基于室内试验及断层滑移弱化本构关系，建立了考虑刚度效应的断层活化力学模型，基于断层流变试验及非定常黏弹塑性蠕变模型，推导了断层剪切蠕变模型；.（2）研发了动力扰动作用下多功能岩石结构面剪切试验装置、岩石裂隙环剪渗流耦合试验系统和活断层错动模拟试验装置三套断层室内试验装置，真实再现了工程现场断层力学响应，实现了相关试验技术的突破；.（3）建立了三轴、剪切等加载条件下完整岩体/断层破坏过程中氡释放室内试验方法，揭示了深部洞室围岩中氡释放与迁移机制，提出了深部洞室群氡气释放与迁移数值模拟方法和断层自发破裂发震模拟方法及断层活化等效震源模拟方法，形成了深部洞室群断层-围岩-氡协同响应流固耦合数值模拟技术；.（4）研发了两套断层张开-错动变形现场监测装置，提出了深部断层活化的监测识别方法，基于室内试验、现场监测和数值模拟建立了考虑断层活化特性的深部洞室群稳定性与环境安全性综合评价方法。