多尺度岩体应力波传播特性及其对震源定位精度影响研究

When a wave propagates across a rock mass, wave reflection, transmission, scattering, and attenuation occur at macroscopic and mesoscopic defects. Exploring the propagation and attenuation law of stress waves in rock mass is not only the precondition of dynamic response analysis and stability evaluation of rock mass, but also the theoretical basis for improving the accuracy of seismic source location. This project is devoted to study wave propagation characteristics of rock mass with mesoscopic or macroscopic defects under different stress states from the perspectives of rock block and rock mass scales. First of all, the mechanism of mesoscopic and macroscopic defects on stress wave propagation is researched respectively, which includes: the relationship between description parameters of mesoscopic defects and the characteristic parameters of stress wave response is established; the characterization indexes of anisotropy and non-uniformity of rock based on the wave propagation theory are obtained; the propagation and attenuation law of stress wave in rock mass under complex macro defects and their combination is revealed. Based on above study, the mechanism of interaction of macroscopic and mesoscopic defects on stress wave propagation is analyzed and discussed. Then the scale effect of wave propagation in rock mass is demonstrated. Furthermore, effects of wave propagation characteristics in rock mass on velocity model construction, first-arrival pickup and waveform identification, sensor layout and location algorithm optimization are studied systematically. The mechanism of wave propagation characteristics on the location accuracy of seismic source is discussed from the perspectives of indoor small scale and field engineering scale. This project is aimed at further improving wave propagation theory in rock mass and providing theoretical support for the studies related to dynamic characteristics of rock mass and the optimization of source location.

应力波在岩体中传播时会在宏、细观缺陷处发生透反射、散射及衰减等现象。探究应力波在岩体中的传播与衰减规律是岩体动力响应分析和稳定性评价的前提条件，也是提高震源定位精度的理论依据。本项目拟从岩块和岩体两个尺度入手，研究不同应力状态下含有细、宏观缺陷岩体的应力波传播特性，分别探究细观、宏观缺陷对应力波传播的作用机理，建立岩石细观缺陷的描述参数与应力波响应之间的关系，揭示复杂宏观缺陷及其组合下应力波传播与衰减规律，获得各向异性、非均匀性的表征指标。在此基础上，探讨宏、细观缺陷耦合作用下对应力波传播的作用机理，揭示岩体中应力波传播的尺度效应。此外，系统研究岩体应力波传播特性对速度模型构建、初至拾取和波形识别、传感器布设、定位算法优化等的影响，探讨应力波传播特性对震源定位精度的作用机理。本项目旨在进一步完善岩体应力波传播理论，为岩体动力特性研究和震源定位优化提供理论支撑。

研究应力波在岩体内的传播与衰减特性及其对震源定位精度的影响是岩体稳定性评价及工程灾害预警领域具有基础性和系统性的重要课题。本项目从室内小尺度岩块和现场大尺度岩体两个尺度入手，采用室内实验、现场测试、理论分析和数值模拟相结合的综合研究方法，研究了不同应力状态下含有细、宏观缺陷岩体的应力波传播特性，探讨了岩体应力波传播特性对震源定位精度的影响；开展了波传播反问题研究，论证了基于波传播参量变化求解节理刚度的可行性；基于聚类分析、信息熵和临界慢化理论等数学方法建立了岩体破裂源的动态表征方法；统计了不同岩石类型不同应力状态下的岩体破裂源信号的主频、能量、空间位置等信息，建立了声发射主频统计结果与岩石破裂类型之间的对应关系；分析了岩体破裂过程中微震参数的响应特征，揭示了岩体破断面的形态及其发育过程; 以微震原始波形数据直接作为输入，而监测区域的三维高斯分布函数作为输出，以震中误差、震源深度误差、绝对误差作为指标对模型进行评估，构建了一种用于震源定位的全卷积神经网络模型。研究表明：（1）宏细观缺陷对波传播的作用主要体现在波速、振幅和主频的衰减上，高频成分衰减更为显著，与慢度相比波衰减对于缺陷的存在更为敏感，应力状态对波能量衰减和高频信号过滤效应有明显影响；（2）基于波形主频特征统计分析，提出了确定声发射参数分析中裂纹分类准则的方法，压缩状态下脆性岩石的RA和A-FRQ值的最佳比率大约为1：100至1：500；（3）基于聚类分析、信息熵和临界慢化理论等提出的空间相关方向性指标及其信源熵等参数能够表征岩体破裂源演化规律，揭示了顶板多关键层破断及微破裂机制；（4）构建的全卷积神经网络模型成功应用于水电站地下厂房微震事件定位，大大提高了定位精度和效率。研究成果进一步完善了岩体应力波传播理论，为岩体动力特性研究和震源定位优化提供理论支撑。