预置裂隙花岗岩受载破坏双差层析成像研究

Study on double difference tomography for loading failure of preset fracture granite

为了更好地研究岩石破坏机理,开展了预置有剪切破坏裂缝形成预置破坏区的花岗岩受载破坏实验。利用微震监测系统采集岩样受载过程微震事件,采用双差定位算法对微震事件数据进行分析,计算了岩样受载过程各位置的岩石波速分布,并对应力分布进行了反演。结果表明,花岗岩岩样受载过程中沿预置的裂隙面失稳,利用双差算法对微震事件重新定位,多数微震事件数分布于预置断裂面或其周围。双差层析成像后的岩石波速等值线图显示,不同受载阶段预置破坏区波速结构与微震事件数量、强度分布及应力曲线特征有很好相关性,验证了该计算方法的可靠性。

In order to study the failure mechanism of rock better,the loading failure experiments of granite with preset failure area formed by shear failure fracture were conducted. The micro-seismic events in the loading process of granite specimens were collected by using the micro-seismic monitoring system,and the data of micro-seismic events were analyzed by using the double difference location algorithm. The distribution of granite wave velocity in each position during the loading process of granite specimen was calculated,and the inversion was carried out on stress distribution. The results showed that the granite specimen failed along the preset fracture plane during the loading process. Through the relocation of micro-seismic events by the double difference algorithm,most of the micro-seismic events were located within or around the preset failure plane. The contour map of granite wave velocity after double difference tomography showed that the wave velocity structure in preset failure area had good correlation with the amount,strength distribution and stress curve characteristics of micro-seismic events in different loading stage,which verified the reliability of this calculation method.