中文摘要：

采用力学试验手段探究岩石受压情况下内部裂纹扩展贯通机制是了解岩石破坏失稳机制的重要手段。由于无法观察真实岩体内部裂纹扩展过程且CT扫描实时性不足等原因,自行研制了一种各项性质与岩石接近的透明类岩石材料,以观察研究其内部三维裂纹的扩展贯通机制。这一方法克服了真实岩体不透明的特点,可更方便地观察岩体内部裂纹萌生、扩展不同阶段的形状。然后制作了一批内置单裂隙和双裂隙的试件,在RMT-150B多功能全自动刚性岩石伺服试验机上进行单轴压缩试验,详细观察研究了单裂隙和双裂隙试件在不同岩桥角和裂隙间距情况下的裂纹扩展贯通模式以及裂隙数量和间距对试件抗压强度的影响,并从理论方面对翼形裂纹的扩展过程进行了解释。试验表明,在不同的岩桥角和裂隙间距下,次生裂纹将呈现不同的扩展贯通模式,试验中观察到的次生裂纹有张拉翼裂纹、与翼裂纹反向生长的反翼裂纹和拉剪作用下的花瓣状裂纹等,试件最终破坏是各种形式的裂纹汇合贯通的结果。裂隙的存在极大地降低了试件的抗压强度,且随着裂隙数目增加,试件峰值强度呈降低趋势,同时裂隙间距也对试件的峰值强度产生一定的影响。试验成果对分析真实岩体的破坏失稳机制有着重要的参考价值。

英文摘要：

Experimental studies are preformed to investigate the mechanism of 3D crack propagation and coalescence in rock under compression, which is significant to understand the damage mechanism and instability of rock mass. Since internal cracks in rock cannot be directly observed and the CT scanning technique is lack of real-time capability, a type of transparent rock-like material is developed to investigate the mechanisms of 3D cracks propagation and coalescence. This transparent material has similar cracking behaviour as rock material, and thus it is convenient to observe the internal crack initiation and propagation. Uniaxial compression tests are conducted on transparent specimens containing build-in single and double pre-exciting cracks using a RMT-150 B multifunction automatically rigid servo testing machine. The patterns of 3D cracks propagation and coalescence of specimens with different bridge angles and crack spacings are obtained by detailed observation. Additionally, the influence of different preexisting crack number and crack spacings on peak strength is examined. At last, a theoretical explanation is presented to explain the crack propagation process. The results show that the propagation and coalescence modes of secondary cracks are controlled by different bridge angles and crack spacings. The secondary cracks included wing crack, anti-wing crack（growing in opposite direction with wing crack）, and petal-shaped crack（caused by tensile and shear stress）. The coalescence of all kinds of cracks leads to the final failure of specimens. The existence of cracks significantly reduces the compressive strength of specimens, and as the number of crack increases, the peak strength exhibits a trend of decline. Furthermore, the crack spacing also affects the peak strength. This research results provide a valuable guide for analyzing the mechanism of rock damage and instability.