- 期刊
以聲射法研探類岩於斜剪試驗之破壞演化
A Study on the Fracture Evolution of Rock-Like Material under Inclined Shear Test by Acoustic Emission
摘要
以非破壞聲射技術配合自行研發之斜剪試驗儀，研探水泥砂漿試體在剪力作用下之微、巨觀破壞機制。採用開口位移回授控制穩定之破壞，求取不同剪角（β）下試體受剪之完整加載曲線。利用聲射技術蒐集岩材內部受剪產生微震裂源之發生時機與空間分佈情形，可探討類岩材料之叢聚與裂衍之破壞演化特徵。由試驗結果顯示，剪力強度隨剪角增大而降低，且其破壞之裂衍角有方向改變之趨勢，乃至其值亦隨之增大，亦即產生之裂縫由相對高正向應力之剪力裂縫，漸變成相對低正向應力下允許膨脹之張力裂縫。此外，由初裂後之微震裂源分佈可求得材料之剪裂帶分佈帶寬，發現分佈帶寬隨剪角增加而增加。
並列摘要
In this study, non-destructive acoustic emission technology is used with a self-developed inclined shear instrument to investigate the microscopic and macroscopic failure mechanisms of cement mortar specimens undergoing shear loading. Crack opening displacement feedback is used to control stable failure, obtaining complete loading curves of shearing specimens at different shearing angles. Acoustic emission technology is used to obtain the timing and spatial distribution of microcracks developed in the specimens so that the characteristics of the localization and crack propagation patterns can be investigated. Test results indicate that shear strength is reduced with increasing shear angle. In addition, the fracture propagation angle tends to change direction and its value also increases. The cracks thus produced gradually change from shear cracks (under relatively high normal stress) to tension cracks that allow expansion (under relatively low normal stress). From the distribution of microseismic sources after the initiation of cracks, the width of the shear crack band of the specimen can be obtained. It is discovered that the distribution bandwidth increases with increasing shear angle.