Abstract

A series of triaxial unloading tests on integrated rock, triaxial compression tests and creep tests on unloading-cracked rock were carried out on dry and saturated specimens. The spatial and temporal distribution of microcracking process were obtained with the help of 3D acoustic emission (AE) monitoring system. The experiment data revealed that the saturation had a degeneracy effect on the transient failure strength of integrated granite, and the failure strain at high confinement. The creep characteristics of unloading-cracked granite in lateral direction were found to be greater than in axial direction. At high confinement, the critical strain of creep failure, the creep deformation and the lateral creep strain rate were shown to be degraded by the saturation. When the applied stress surpassed the level of 90% of the compressive strength of unloading-cracked specimen, the variation of AE event showed a consistent tendency with the evolution of lateral strain, and the AE events were found to be mainly accumulated along the macroscopic failure surface. The AE signal was noticed to be more sensitive than the macroscopic deformation to the occurrence of creep failure. Before the appearance of large increase in lateral strain, the rapidly increase of AE activity had occurred.

摘要

对干燥和饱和试样进行了一系列综合岩石三轴卸载试验、卸载开裂岩石三轴压缩试验和蠕变试验。借助3D声发射（AE）监测系统获得微裂纹过程的时空分布。实验数据表明，饱和度对整体花岗岩的瞬态破坏强度和高约束破坏应变具有退化作用。卸载开裂花岗岩的横向蠕变特性大于轴向。在高约束条件下，蠕变破坏的临界应变、蠕变变形和横向蠕变应变率显示出因饱和而降低。当外加应力超过卸荷裂纹试样抗压强度的90%水平时，AE事件的变化与横向应变的演变呈现一致的趋势，发现AE事件主要沿宏观破坏累积表面。注意到 AE 信号比宏观变形对蠕变破坏的发生更敏感。在横向应变出现大幅增加之前，AE 活性迅速增加。