大型地下水封石油洞库微震损伤效应及力学参数反馈研究

The construction of large-scale water sealed underground oil storage caverns is an important part in the strategic oil reservation of China, which is vigorously implemented in the current stage. For such a structure of rock mass with a high wall, no lining and a large span, its stability problem during excavation disturbances and operation after completion will become increasingly prominent. This project took the large-scale water sealed underground oil storage cavern in Jinzhou, Liaoning province as the background, and the analysis is based on the mechanics theory of “Microseismic effects and rock damage are coherent”. By means of microseismic monitoring, numerical simulation and theoretical analysis, the in-depth studies of the development rule of the microcracks in rocks of the cavern under cyclic loadings such as excavations or deposit/withdrawal storages, can be carried out. According to sufficient information of the focal points such as Location of microcracks/ Size/Energy/ Stress reduction, a state equation can be established which indicates parameter changes of rockmass mechanics in damaged area by means of microseismic monitoring. Upon the combination of the geological model within the scope of microseismic monitoring and the three-dimensional numerical model of mechanics, a dynamic correction of parameters of rockmass mechanics within the scope can be achieved. This will bring forward a set of design methods focused on the leakproofness evaluation method, which applies to large-scale underground oil storage caverns. There are vital engineering application value and theoretical significance to the construction of China's energy strategic reserve base and underground raw material storage for large-scale petrochemical enterprises.

大型地下水封石油洞库的建设是我国现阶段大力实施建设的石油战略储备一种重要方式。对于这种具有高边墙、不衬砌和大跨度的特殊岩体结构，其开挖扰动作用下和后期运营过程中的稳定性问题将日益突出。本课题以正在建设中的辽宁省锦州大型地下水封石油储备洞库为研究背景，基于“岩石微震效应与岩体损伤具有一致性”的物理力学基础，通过微震监测、数值模拟及理论分析等手段，深入研究开挖卸荷和储物注取等循环荷载作用下洞库岩体微破裂的发展规律；根据微破裂点的空间位置、震源尺寸、能量、应力降等丰富的震源信息，建立微震监测损伤区域岩体力学参数强度变化的表述方程，将微震监测区域的地质模型和三维数值力学模型相结合，实现对微震区域岩体力学参数的动态修正；提出一套适用于评价地下石油水封洞库密闭性的方法，对我国能源战略储备基地和大型石化企业地下储备原料库的建设，都具有重要的工程应用价值和理论意义。

大型地下水封石油洞库的建设是我国现阶段大力实施建设的石油战略储备一种重要方式。对于这种具有高边墙、不衬砌和大跨度的特殊岩体结构，其开挖扰动作用下和后期运营过程中的稳定性问题将日益突出。本项目以辽宁省锦州大型地下水封石油储备洞库为研究背景，基于“岩石微震效应与岩体损伤具有一致性”的物理力学基础，通过理论分析、微震监测及数值模拟等手段，深入研究开挖卸荷作用下洞库岩体微破裂的发展规律；提出一套适用于评价地下石油水封洞库密闭性的方法，取得了以下主要成果：.（1）首次尝试将微震这种三维“体”监测方法构建于地下水封石油洞库水幕巷道中，对其下方24m处的储油洞室开挖过程中的洞库围岩微破裂进行实时监测，可以得出：采用人工定点敲击试验方法确定了研究区域岩体整体等效P波波速为5 200 m/s，平均误差小于8m。.（2）从地下水封石油洞库围岩微震活动性空间分布规律看，由于开挖作用使得能量释放逐渐向辉绿岩脉、花岗细晶岩脉转移，高能量的释放导致这些岩脉“过度”损伤，诱发大量的微破裂。其结果印证了所构建的微震监测系统可帮助圈定洞库围岩未知岩脉和软弱结构面等的分布。.（3）通过水封石油洞库开挖过程中的微震事件密度变化规律研究，实现对开挖卸荷过程中水封洞库围岩24小时连续监测和安全预警。为水封石油洞库运营期微震监测系统的构建与实施提供参考依据。.（4）将一个全新的数值模拟方法——连续-非连续单元法（CDEM）和一个六通道的微震监测系统集成到统一平台上，研究了微震事件和微裂隙的发育。通过微震监测数据证实模拟结果，CDEM数值模拟和微震监测系统的集成平台在捕捉地下水封石油洞库的微裂隙上很有成效，可为稳定分析和风险评估的预警奠定基础。.