深部地下洞室开挖微震响应机理与围岩变形反馈分析

This project is based on the deep underground powerhouse caverns to be constructed at the Shuangjiangkou hydropower station in Southwest China. Focusing on the two key factors influencing the surrounding rock mass stability of deep underground caverns, i.e. “strong unloading disturbance” and “complicated geological structures”, this proposal is intended to investigate the microseismic response mechanisms and stability of surrounding rock mass using the incorporated approach including microseismic monitoring, numerical simulation and theoretical analysis. A microseismic monitoring system in the deep underground caverns is established. The correlation between microseismic activities and construction process, geological structures, stress field evolution is studied. The source parameter characteristics and fracture mechanisms of microseismic clusters are analyzed. The dominating factors of damage, potential failure modes and characteristics of surrounding rock mass can be revealed. The evolution laws of multiple microseismic source parameters during the surrounding rock mass large deformation are investigated and a microseismic forecasting method is proposed for the surrounding rock mass large deformation of the underground caverns. A microseismic source fracture size based damage constitutive model of rock mass is built up and the surrounding rock mass deformation feedback analysis of the underground caverns is conducted. The potential outcomes of this proposal can contribute to better damage mechanism analysis, stability evaluation and dynamic disaster forecasting for surrounding rock mass of deep underground engineering with both scientific significance and valuable engineering applications.

以即将开工建设的双江口水电站深部地下厂房洞室群为研究对象，聚焦“强卸荷扰动”和“复杂地质构造”这两项影响深部岩体工程围岩稳定性的关键因素，利用微震监测、数值模拟和理论分析等方法，致力于研究地下洞室开挖微震响应机理与围岩变形稳定性。构建深部地下洞室微震监测系统，探讨微震活动与施工动态、地质构造、应力场演化之间的联系，研究不同微震聚集区震源参数特征及破裂机制，揭示地下洞室围岩损伤的控制性因素、潜在破坏模式及风险特征；研究地下洞室围岩大变形过程微震震源多参数演化规律，建立地下洞室围岩大变形的微震判别方法；建立基于震源破裂尺度的岩体损伤本构模型，开展考虑微震损伤效应的地下洞室围岩变形反馈分析。该研究为深部地下工程围岩损伤机理分析、变形稳定性评估以及动力灾害预警提供指导方法，具有重要的科学意义和工程应用价值。

以西南地区在建双江口水电站深部地下厂房洞室群为依托工程，基于微震监测技术，结合数值模拟和理论分析，系统开展了深部地下洞室群开挖过程岩石破裂损伤致灾机理与变形破坏预警研究。构建了深部地下洞室群开挖过程微震监测系统，实时获取了开挖卸荷诱发的岩石微破裂时空演化信息，建立了微震活动与施工动态的联系，识别和圈定了地下洞室不同时段的主要损伤区域；深入研究不同控制性因素作用下微震事件的b值、横纵波能量比等参数特征，揭示了不同微震聚集区的岩体损伤特性；提出了基于微震震源多参数的地下洞室围岩大变形微震预警方法，动态指导地下洞室开挖进度和加固措施；建立了考虑微震震源半径的损伤本构关系，将微震信息导入地下洞室三维数值模型，实现了考虑微震损伤效应的地下洞室围岩变形反馈分析。研究成果可为深部地下工程围岩稳定性评价及灾害预警防控提供技术指导，具有重要的科学意义和应用价值。