Analysis on microseismic characteristics and stability of the access tunnel in the main powerhouse, Shuangjiangkou hydropower station, under high in situ stress
Analysis on microseismic characteristics and stability of the access tunnel in the main powerhouse, Shuangjiangkou hydropower station, under high in situ stress
复制标题
双江口水电站主厂房进洞高地应力微震特征及稳定性分析
DOI：
10.1007/s10064-020-01738-6
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发表时间：
2020-02-25
影响因子：
4.2
通讯作者：
Zhang, Yinghao
中科院分区：
文献类型：
--
作者：
Liang, Zhengzhao;Xue, Ruixiong;Zhang, Yinghao
双江口水电站主厂房交通洞埋深大，地应力高，地质条件复杂。建立了微地震监测技术，用于监测开挖初期围岩内部微裂纹的演化过程。通过划定隧道主要病害区，及时预报了隧道左拱肩严重落石。在对比分析交通洞微地震活动规律和现场破坏特征的基础上，提出了微地震事件与岩爆的定量指标。利用微地震同相轴资料分析了日平均视应力差和b值的变化规律。利用三维数值模拟软件RFPA3D对隧道周边损伤分布进行了模拟，定性分析了隧道损伤空间位置与最大主应力方向的关系。研究结果表明，隧道工作面推进速度是影响围岩应力重分布状态的重要因素，微地震事件b值的变化规律能有效预测围岩内部的活动状态，反映围岩的力学性质和应力状态。特别是随着b值的增大，现场冒落块体更加严重，b值较小时，现场围岩相对稳定。b值越小，围岩失稳的风险越大。该方法为预测和评价类似落石的轻微岩爆提供了一种有效的方法。研究成果对现场施工及后期施工规划具有重要的指导意义。
Access tunnel in the main powerhouse of Shuangjiangkou hydropower station was deep buried with high in situ stress and complex geological conditions. Microseismic monitoring technology was established to monitor microcrack evolution process inside the surrounding rock in early excavation stage. Serious falling blocks in the left spandrel of the tunnel were predicted in a timely manner by delimiting major damage areas in the tunnel. Based on comparative analysis on microseismic activity law and field failure characteristics of the access tunnel, a quantitative index was supposed between slight rockburst like falling blocks and microseismic events. Moreover, the change law of daily average apparent stress difference andbvalue were analyzed based on microseismic event data. In addition, a three-dimensional numerical simulation software (RFPA3D) was used to simulate the damage distribution around the tunnel, and a relationship between spatial position of tunnel damage and direction of the maximum principal stress was qualitatively analyzed. The study results showed that advance speed of the tunnel working face was an important factor affecting the state of stress redistribution in surrounding rock mass, and the change law ofbvalues of microseismic events could be used to predict activity state inside the surrounding rock effectively, which reflected mechanical properties and stress state of surrounding rock. In particular, field falling blocks became more serious with increasingbvalue, and field surrounding rock was relatively stable with minorbvalue. A risk of surrounding rock instability was relatively high with smallbvalues. It provided an efficient method of predicting and assessing slight rockburst like falling blocks. The study results can provide significant guidance for field construction and later construction planning.