动静组合荷载作用下裂隙岩体损伤演化特征与变形破坏机理

Focusing on the two key factors affecting the surrounding rock mass stability in deep rock engineering, i.e. “high geo-stress” and “strong dynamic loading disturbance”, this proposal is intended to investigate and discover the dynamic mechanism of fractured rock mass, deformation and damage constitutive model considering the coupled effects of both key influencing factors. A large-scale novel confining static pressure-dynamic coupled loading device“Double confining chambers-Self balanced-Special shaped bar”is developed for the first time to accommodate split Hopkinson pressure bar tests, and a reliable method of applying the confining pressure on the fractured specimens are proposed. A series of one-dimensional static-dynamic coupled loading experiments and three-dimensional static-dynamic coupled loading experiments are subsequently conducted. The damage evolution rules, energy transmission and dissipation mechanism, failure mechanism, and the progressive deformation and fracture mechanism are studied. A dynamic damage constitutive model is built up for fractured rock mass subjected to coupled static-dynamic loads. With application to hydraulic rock engineering projects especially deep underground powerhouse excavation by blasting, a comprehensive method involving microsesmic monitoring and conventional deformation measures has been built up on the selected zones with typical fractured rock mass. This engineering in-situ monitoring is aimed at validating the damage evolution and dynamic constitutive model developed in the laboratory, as well as revealing the damage, deformation and failure mechanism of fractured rock mass under coupled static-dynamic loads. The potential outcomes of this proposal can contribute to a better stability analysis of deep rock mass, interpreting and preventing dynamic hazards with both scientific significance and valuable engineering applications.

本项目聚焦“高地应力”和“强动力扰动”这两项深部岩体工程施工中影响围岩稳定性的关键因素，致力于研究并揭示综合考虑这两项关键因素耦合效应的裂隙岩体动态损伤演化特征和变形破坏机理。研发“双压室自平衡异形杆”动静组合加载实验新型装置与有效实施方法，开展不同构型的类裂隙岩体模型试样在一维动静组合以及三维动静组合荷载作用下的系列动力学实验，研究试样损伤演化特征、能量传递耗散规律以及变形破坏渐进机理，建立动静组合荷载作用下裂隙岩体动力损伤本构模型。依托水电工程高地应力地下洞室爆破开挖工程，圈定典型裂隙岩体试验区域综合进行微震监测及常规监测，验证实验室建立的裂隙岩体动静组合损伤演化规律及动力本构模型，揭示高地应力与强动力扰动耦合条件下裂隙岩体损伤、变形、破坏的动力学特征与演化机制。该研究对于深部岩体工程围岩稳定性分析以及动力灾变机理的认识与防治，具有重要的科学意义和工程应用价值。

本项目紧扣深部裂隙岩体遭受的“高地应力”和“强动力扰动”这两项关键因素，通过室内试验、理论分析、数值研究，并结合微震监测及深地裂隙岩体工程实践，从实验室尺度到工程尺度对动静组合作用下裂隙岩体的动力特性和变形破坏机理开展了深入研究。研究首次将裂隙岩石的破断研究引入动静组合霍普金森压杆实验中,开展了一维动静组合加载下裂隙岩石动力学试验，拓展高速摄影数字图像相关技术，提出全新普适的裂纹分类方式，全面揭示了裂隙岩石动态渐进破断机理；研发了适用于裂隙岩石三维动静组合加载试验的有效围压实施装置，开展了裂隙岩石三维动静组合加载试验，并辅以构建了精确围压伺服控制的三维离散元动静组合实验模拟系统，深刻揭示了预静载、应变率以及裂隙几何构型对深部裂隙岩体在强动力扰动下的力学响应、渐进破断行为、破碎特征以及能量传递耗散规律的影响。结合依托工程（包括在建项目与施工完成项目）微震监测，研究了典型深部裂隙岩体工程围岩微破裂时空演化规律、能量传递释放规律以及与开挖爆破强动力扰动的时空关联，验证了爆破荷载强动力扰动下深部裂隙围岩的破断机理。本项目在深部裂隙岩体动力损伤演化与变形破坏机理方面取得的一系列创新成果，为白鹤滩、乌东德、两河口水电站地下厂房等大型水电地下洞室群施工现场优化爆破工艺参数提供了理论支撑，确保了地下厂房开挖质量，有效控制了高边墙卸荷松弛变形，经济与社会效益显著。.按照项目任务书，截止2021年12月底，项目研究成果发表SCI论文41篇，授权发明专利9项；项目负责人入选第八届教育部科学技术委员会委员（土木、建筑与水利学部）、国家“万人计划”科技创新领军人才；获教育部科技进步一等奖1项；连续三年（2018-2020）入选爱思唯尔中国高被引学者榜单；项目组参加国际学术会议13人次；项目培养博士研究生11人、硕士研究生6人，研究生获全国“最美大学生”、中国大学生年度人物、宝钢教育奖优秀学生特等奖等奖励。项目成果已超额完成预期目标。