深埋隧洞开挖卸荷岩爆孕育过程及微震预警分析

发布时间：2018-08-13 14:55

【摘要】：深埋岩石隧洞工程普遍遭遇突发性和破坏性极大的岩爆灾害,据不完全统计,仅锦屏二级水电站隧洞群已开挖工程就发生不同程度岩爆上千次。面对大量的微震监测数据,由于难以找到微震数据与岩爆孕育过程的内在联系和演化规律,至今在我国还没有非常成功的岩爆监测预报案例,因此,开展深埋隧洞在高应力条件下硬岩的岩爆孕育过程和微震预警问题研究十分必要。论文以岩石损伤力学理论为基础,以数值模拟分析和微震监测为手段,揭示开挖卸荷岩爆孕育过程,基于微震监测数据分析探索岩爆的前兆规律,为岩爆的预警与防控奠定理论与技术基础。建立多种卸荷应力路径和岩体介质条件下的数值模型,进行开挖卸荷引起岩爆孕育过程数值模拟研究。主要内容包括：(1)以试样单轴压缩破裂过程模拟相邻隧洞岩体或者同一条隧洞相向开挖而产生的岩柱型岩爆,揭示微震特性为“前震-主震一余震型”模式；(2)以试样侧压卸荷破裂过程模拟现场高应力下由于开挖引起突然卸荷而产生的岩爆,揭示开挖卸荷诱致岩爆的机理；(3)通过对岩体隧洞单步(一次)开挖和分步(多次)开挖发生岩爆进行数值模拟,揭示微震事件释放能量及频次与施工方式联系紧密,揭示微震事件由无序分布向有序集中发展呈现自组织的基本规律。在力学机理上,认为岩石的非均匀性是岩爆存在前兆的根源,变形的局部化是形成岩爆的内因,而岩石与其周围环境的相互作用是岩爆的外因。基于这方面的认识,根据锦屏二级水电站现场不同地质与开挖条件,提出传感器的布置形式、采集数据工作方式。根据排水洞现场微震监测数据分析,通过对微震事件数目、事件位置、事件能量、能量释放速率、事件聚集密度云图等多因素进行量化,并结合开挖过程的数值模拟,进行岩爆孕育过程的预警分析,揭示极强岩爆和强岩爆的预警机制。对岩爆灾害的预警和防控奠定理论基础,为指导安全施工提供技术保障。根据1#引水隧洞微震监测分析,揭示采用先导洞后TBM落地掘进施工方案,可以降低或者控制发生岩爆。3#和4#引水洞相邻多个工作面同时掘进,通过三维数值模拟和微震监测数据分析,揭示岩爆发生部位受相邻隧洞严重的影响。
[Abstract]:The deep buried rock tunnel engineering is generally met with sudden and destructive rock burst disasters. According to incomplete statistics, only the tunnel group of Jinping II hydropower station has been excavated for thousands of times in varying degrees. In the face of a large number of microseismic monitoring data, because it is difficult to find the inherent relation and evolution law between microseismic data and the process of rockburst inoculation, so far there are not very successful cases of rockburst monitoring and prediction in China, so, It is necessary to study the preparation process of rock burst and the early warning of microearthquakes in deep buried tunnel under high stress conditions. Based on rock damage mechanics theory, numerical simulation analysis and microseismic monitoring are used to reveal the incubation process of excavation unloading rockburst, and the precursor law of rockburst is explored based on microseismic monitoring data. It lays a theoretical and technical foundation for early warning and prevention and control of rock burst. The numerical models of various unloading stress paths and rock mass media are established to simulate the incubation process of rock burst caused by excavation unloading. The main contents are as follows: (1) the rock column rockburst caused by the rock mass of adjacent tunnel or the same tunnel is simulated by the uniaxial compression fracture process of the specimen, which reveals that the microseismic characteristic is the model of "foreshock-main-aftershock type"; (2) simulating the rockburst caused by excavation under high stress, and revealing the mechanism of rockburst induced by excavation unloading; (3) through numerical simulation of rock burst in single step excavation and step by step excavation of rock mass tunnel, it is revealed that the release energy and frequency of microseismic events are closely related to the construction mode. It is revealed that the development of microseismic events from disordered distribution to orderly concentration presents the basic law of self-organization. On the mechanical mechanism, it is considered that the heterogeneity of rock is the root of the precursor of rock burst, the localization of deformation is the internal cause of rock burst, and the interaction between rock and its surrounding environment is the external cause of rock burst. Based on the understanding of this aspect, according to the different geological and excavation conditions of the second stage hydropower station in Jinping, the layout of sensors and the working mode of collecting data are put forward. Based on the analysis of microseismic monitoring data in drainage tunnel field, the number of microseismic events, event location, event energy, energy release rate, event aggregation density cloud map and so on are quantified, and the numerical simulation of excavation process is combined. The early warning mechanism of extremely strong rock burst and strong rock burst is revealed by early warning analysis of the inoculation process of rock burst. It lays a theoretical foundation for early warning and prevention and control of rock burst disaster and provides technical guarantee for guiding safe construction. According to the microseismic monitoring and analysis of 1# diversion tunnel, it is revealed that the construction scheme of TBM landing tunneling after pilot tunnel can reduce or control the occurrence of rockburst. The excavation of several faces adjacent to the diversion tunnel can be reduced or controlled at the same time. Through 3D numerical simulation and data analysis of microseismic monitoring, it is revealed that the location of rock burst is seriously affected by adjacent tunnels.
【学位授予单位】：东北大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TV554

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