卸围压路径条件下大理岩破坏过程的声发射特性研究.docVIP

  卸围压路径条件下大理岩破坏过程的声发 射特性研究# 丛宇，王在泉** 5 10 15 （青岛理工大学土木工程学院） 摘要：为探讨破坏过程中应力路径对声发射特征的影响，对大理岩进行常规三轴压缩与恒轴 压、卸围压试验，试验结果表明：试样声发射特征随路径而变化，常规三轴路径试验的声发 射计数率最大值滞后于应力峰值，出现在峰后应力突降处，而恒轴压、卸围压路径试验的最 大计数率出现在应力峰值处；岩样常规三轴路径破坏前声发射事件波动与平静期相互交替， 恒轴压、卸围压路径则明显更具有突发性；低围压下的卸围压试验，卸荷处的声发射事件计 数率降低非常明显，围压越高，岩样破坏持续时间越长，破坏时声发射事件计数率越高；卸 荷速率越高，岩样卸荷后的平静期越短，破坏全过程中的声发射计数率最大值越高；塑性阶 段卸围压，卸荷点处会出现少量计数率较高的声发射事件，低于破坏时出现的声发射计数率。 关键词：岩土工程；声发射；应力路径；恒轴压、卸围压；卸荷速率。 中图分类号： TU 45 20 EXPERIMENTAL STUDY ON ACOUSTIC EMISSION FEATURES OF MARBLE DURING FAILURE PROCESS UNDER UNLOADING CONFINING PRESSURE PATH 25 30 35 40 45 CONG Yu, WANG Zaiquan (School of Civil Engineering,Qingdao Technological University) Abstract: To discuss the relationship between stress path and emission characteristics during failure process, the marble experiments of conventional triaxial compression, constant axial stress and unloading confining pressure were carried out. The results show that there are different acoustic emission features in various stress paths. The maximum of acoustic emission count rate lags behind the stress peak in conventional triaxial compression experiment while the maximum happens at the stress peak during the experiments of constant axial stress and unloading confining pressure; Before conventional triaxial compression failure, the acoustic emission of the rock sample highlights the alternation between active and quiet period, and the path of constant axial stress and unloading compression possesses more burstiness; Under low confining pressure, the experiment of unloading confining pressure reveals that the acoustic emission count rate falls evidently at the unloading position, the higher the confining pressure is, the longer the rock failure endures, the higher the acoustic count rate becomes at the failure; The higher the rate of the unloading pressure is, the shorter the quiet period of the sample is after the unloading, the higher the acoustic count rate becomes during the whole failure process; When unload