论文部分内容阅读
为研究闪长岩在单轴加载过程中的声发射和各向波速变化规律,在单轴阶段加载和循环阶段加载条件下,对闪长岩岩样破裂过程中的声发射累计数、不同应力水平不同方向的波速、切线模量、轴向应变速率进行了研究。实验结果表明:(1)随着应力水平的增高,声发射事件数不断增加,在高应力水平(约80%峰值强度)时,声发射累计数急剧增多,随后切线模量出现震荡变化。(2)在加载过程中,压密程度及裂纹扩展方向对波速产生了巨大的影响,导致不同方向波速在不同的应力水平呈现出不同的变化规律,由此可以推测破裂面位置和破裂模式。在较高应力水平下(约60%峰值强度),平行于加载方向的波速趋于稳定,而垂直于加载方向的波速则持续下降,故用垂直于加载方向传播的波速预测岩石的破坏更具可靠性。(3)随着应力的增加,应变速率有逐渐减小的趋势,但临近岩石破裂时无异常变化出现,说明利用变形观测难以预测此类岩石的破坏。以上研究表明,根据纵波波速、声发射累计数和切线模量的变化可以有效预测岩石的破坏。
In order to study the regularity of acoustic emission and velocity variation during the uniaxial loading of diorite, under the condition of uniaxial loading and cyclic loading, the cumulative number of acoustic emission during rock dilapidation of rock specimen, different stress Wave velocity, tangent modulus and axial strain rate in different horizontal directions were studied. The experimental results show that: (1) As the stress level increases, the number of acoustic emission events increases continuously. At high stress level (about 80% of the peak intensity), the cumulative number of acoustic emission increases sharply, and then the oscillation of the tangent modulus changes. (2) During the loading process, the degree of compactness and crack propagation direction have a huge impact on the wave velocity, resulting in different direction of wave velocity in different directions showing different variation rules, which can infer the rupture surface location and mode of rupture. At higher stress levels (about 60% of peak intensity), the wave velocity parallel to the loading direction tends to stabilize, whereas the wave velocity perpendicular to the loading direction continues to decrease so that the failure of the rock is predicted by the wave velocity perpendicular to the loading direction reliability. (3) With the increase of stress, the strain rate tends to decrease gradually, but there is no abnormal change near the rock rupture, which shows that it is difficult to predict the damage of such rock by deformation observation. The above studies show that rock damage can be predicted effectively by the variation of longitudinal wave velocity, cumulative acoustic emission and tangent modulus.