Evaluation of Rock Inclusion Geometrical Complexity and its Influence on Fracturing Process by AE Measurement

地下岩体和岩石边坡由具有不同物理性质和几何形状的各种岩石类型组成。在这样的岩石工程场地中，当含有包裹体的岩石受到应力变化的影响时，往往会发生意想不到的破坏。根据基质岩石中夹杂物的几何形状和物理性质，应力集中会导致声发射（AE）局部破裂，并可能发生灾难性破坏。为了监测不稳定的岩石区域，使用AE技术，因此，重要的是要知道夹杂物岩石的功能和AE activity.In这项研究中，使用圆柱形和板形的安山岩和凝灰岩，巴西和单轴压缩试验组成的岩石标本进行了确定AE源的位置和复杂性的夹杂物的几何形状出现在切片标本截面的表面之间的关系。几何复杂性用纹理分析指标表示。同时，为了评估局部应力集中区域，对切片试件截面进行了二维有限元分析。加载过程中的AE事件的数量被发现取决于夹杂物体积的标本的比例。安山岩区的AE波形比凝灰岩区的AE波形包含更高的频率成分.大多数声发射源位于沿着最终断裂面;其中一些位于沿着夹杂物-基体边界，有限元估计该边界会集中局部应力。更多的AE源被发现存在于切片中，具有更高的复杂性指数值。据认为，局部应力集中发生在具有复杂结构的部分，因此，更多的微破裂与AE产生。

Underground rock masses and rock slopes consist of various rock types having different physical properties and geometry. In such rock engineering sites, unexpected failures tend to occur when rocks containing inclusions are affected by stress change. Depending upon geometry and physical properties of the inclusion in matrix rock, stress concentration induces local fractures with acoustic emission (AE) and catastrophic failure can occur. To monitor an unstable rock area using AE techniques, it is therefore important to know the relationship between inclusion rock features and AE activity.In this study, using cylindrical and plate-shaped rock specimens consisting of andesite and tuff, Brazilian and uniaxial compression tests were carried out to determine the relationship between AE source locations and complexity of inclusion geometry appearing on the surfaces of sliced specimen sections. Geometrical complexity was represented by some texture analysis indexes. Also, to evaluate local stress concentration areas, 2-D FEM analysis was conducted for the sliced specimen sections.Experimental and analytical results are :1. The number of AE events during loading was found to depend on the ratio of inclusion volume to the specimen. The AE waveform from the andesite area contained higher frequency components than the tuff area waveform.2. Most AE sources were located along the eventual fracture plane ; some of them were located along the inclusion-matrix boundary which was estimated to concentrate local stress by FEM.3. More AE sources were found to be present in sliced sections with a higher complexity index value of inclusion. It was believed that local stress concentration occurred in sections with a complex structure and that more microfracturing was therefore generated with AE.