深埋洞室群断裂型岩爆诱发强地震动的频控致灾机制研究

Aiming to the bottleneck problem that lack of the understanding of frequency effect of strong ground motion which seriously restricts the interpretation of occurrence and disaster-caused mechanism of rupture-type rockburst, relying on deep underground laboratory engineering in Jinping and its hard-rock environment with preferred structure, the frequency-controlled mechanism of occurrence and disaster-caused process of rupture-type rockburst will be revealed from a new perspective of “frequency-controlled effect of ground motion”. A new method of seismic source simulation will be established considering structure type, stiffness pattern and dynamic rupture, matching joint monitoring technique of seismic motion in wide frequency band, in order to interpret mechanic behavior of dynamic rupture and spectrum formation mechanism of seismic source of rupture-type rockburst. The hybrid numerical method of DGFEM and DEM will be constructed, mechanic model of finite rupture seismic source and nonlinear velocity field model will be proposed, thus ground motion simulation and dynamic modeling of the chained dynamic interaction will be implemented, considering whole process from seismic source excitation and seismic motion propagation to strong ground motion effect and induced failure of rock masses, and then the frequency dependent propagation law of ground motion under the control of preferred structure and complicated rock mass structure will be revealed. Based on bonded block DEM characterization and dynamic analysis of excavation structure, excavated damage zone and support system, the cause of strong ground motion and frequency-controlled mechanism of induced rock mass failure and caused damage will be revealed. The research can open up a new direction for the mechanism study of rupture-type rockburst, and provide a novel theory and method for the scientific design of support system and the reasonable prevention and control of rockburst.

针对强地震动频率效应认知匮乏而严重制约断裂型岩爆发生与致灾机理解译的瓶颈问题，拟依托锦屏深部地下实验室洞室群工程及其复杂构造硬岩环境，从“地震动频控作用”全新视角揭示断裂型岩爆发生与致灾过程的频控机制。建立考虑结构类型、刚度模式和动态断裂的断裂型岩爆震源模拟试验新方法，匹配宽频段震动联合监测分析技术，解译震源动态断裂力学行为与频谱形成机制。构建间断Galerkin有限元-离散元耦合数值分析方法，提出有限断裂震源和非线性速度场模型，实现考虑“震源激发->地震动传播->强地动效应诱发围岩破坏”链式动力作用全过程的地震动模拟与动力仿真，揭示复杂地质构造与岩体结构控制下地震动频率相关传播规律。基于开挖结构、开挖损伤区与支护系统的粘结块体离散元表征和全动力分析，揭示深埋洞室群强地动成因及其诱发围岩失稳成灾的频控机制。本研究可为断裂型岩爆机理研究开辟新方向，为岩爆支护系统设计与防控提供新理论方法。

项目研究紧抓贯穿断裂型岩爆从“震源激发->地震动传播->强地动效应诱发围岩破坏”链式动力学作用过程的震动频率这一关键控制因素，以地震动频率对链式动力学过程的控制作用为突破口，从地震学、应力波传播理论和地震动频率相关行为等全新视角，揭示了深埋洞室群断裂型岩爆发生机理与致灾机制。本研究中构建了表征深部岩体结构特征与结构面几何形态特征的隧洞无人机SfM摄影测量与数字模型重构技术和结构面识别技术，综合运用该技术解决了复杂深部硬岩结构表征与断裂型岩爆震源动态断裂机制研究；研发了基于FDEM数值方法的硬岩细观结构表征方法，探究了矿物几何非均性和力学参数非均质对高应力诱发断裂过程的控制作用，识别了震源断裂机制，解决了细观尺度上对震源断裂特征和成因机理的深入认知问题；建立了断裂型岩爆震源的定量表征方法理论，与谱元方法相结合揭示了震源辐射地震波传播规律和地震波与隧洞结构相互作用效应的规律；形成了有限元-离散元耦合数值方法框架，探究了断裂型岩爆链式动力作用全过程的频控机制，识别了震源诱发地震波的频谱特征、地震波在复杂岩体结构中的传播规律以及在地震波波长和隧洞洞形、跨度与开挖损伤区等关键因素控制下地震动放大效应和强地动形成规律，为定量评估断裂型岩爆烈度等级以及破坏范围提供了新技术。项目研究将为川藏铁路深埋隧道等重大国家战略工程中断裂型岩爆机理研究开辟新方向，为岩爆支护系统设计与防控提供新理论方法。