抄録
The source location of acoustic emission (AE) events was performed during the creep of Ohshima granite under uniaxial compression. During the stage of loading up to the creep stress, AE events were randomly distributed throughout the sample. As soon as the transient creep was initiated, abrupt migration and clustering of AE events into several near-surface zones were clearly observed. These migration and clustering strongly suggest the rapid anisotropic development of dilatancy at the very beginning of transient creep. These clusters, though the shape of each one was“volumetric”, formed a shear band at an angle 30∼35° to its loading axis. The spatial distribution pattern of AE events established in this stage was retained until the main fracture. By the end of transient creep. AE events began to concentrate into one of these clusters; on the other hand, the activities of other clusters were reduced gradually. This change was spread broadly and continuously in time until the main fracture. There was no fundamental difference in the spatial distribution pattern of AE events between the stationary and the tertiary creep. In the latter half of the creep, the occurrence of AE events was limited within only one cluster which remained active, and the acceleration of AE activity was seen before the main fracture in this cluster. And its shape was spheroidal whose long-axis was parallel to the loading axis.
