单轴压缩作用下砂岩变形规律及声发射特性研究

Study on Deformation Rules and Acoustic Emission Characteristics of Sandstone Under Uniaxial Compression

为了探究砂岩声发射活动及其破坏特征之间的关系,研究声发射活动和砂岩破裂特征的变化规律,进行了砂岩声发射力学特性试验。研究结果表明:不同加载阶段砂岩声发射活动强弱不同,与其内部的裂隙发育演化过程有密切关系。当应力高于起裂应力时,声发射事件逐步上升,砂岩体积逐渐增加;当应力高于扩容应力时,声发射事件急剧上升,占全过程的53.9%,体积应变值在该阶段达到最大。在砂岩破坏过程中,声发射活动越剧烈,体积应变绝对值越大,体积应变和声发射活动都随着砂岩内部裂隙发展,当砂岩开始产生微裂隙时,声发射能量相对于声发射事件率在接收信号方面有一定滞后性。

In order to explore the relations between acoustic emission and damage features of sandstone, the changeable laws between the two were studied and the mechanical characteristics experiments about acoustic emission of sandstone were carried out. The experiment results showed that the strength over acoustic emission was different at different loading phases which were closely related with the development and evolution of inner cracks. When stress was higher than initial crack stress, the events of acoustic emission and the sandstone volume gradually increased. When stress was higher than expansion stress, the events of acoustic emission increased rapidly accounting for 53.90% of the whole process, and the volume strain reached to the maximum. In the damage process of sandstone, the more intense the acoustic emission, the greater the absolute value of vol- ume strain was, so both the volume strain and the acoustic emission changed along with the internal cracks of sandstone. While the sandstone begun to generate minute cracks, the acoustic emission energy had lagged behind the acoustic emission event rate in terms of received signal.