动载下3条断续裂隙岩样的裂缝贯通机制

采用含3条断续预制裂隙的类砂岩模型试样进行单轴动力加载试验，对不同裂隙空间位置条件下断续裂隙岩体中裂隙的贯通机制进行了研究。静、动荷载下的对比研究成果显示：不同空间位置的裂隙贯通方式存在较大差异，且对动载的响应不同；动载下分支裂纹扩展及贯通具有惯性效应，即动载下裂尖次生共面、次生倾斜裂纹起裂后易朝原起裂方向快速发展，动载下易在两预制裂隙内端部产生直接贯通。这与静载下岩桥处的贯通常通过分支裂纹拐折扩展、相连不同，这也是导致裂隙试样中低应变速率下强度增大（即速率效应）的主要原因。同时，试验结果也表明：含裂隙试样静、动荷载下裂隙间的多次贯通是导致其呈现出渐进破坏特征的主要原因。

Fracture coalescence mechanism of three-intermittent-flaws rock specimen under dynamic loading

The mechanism of the fracture coalescence for intermittently cracked rock mass is studied under uniaxial dynamic loading. The specimens made of sandstone-like modeling material contain three pre-existing flaws with different geometry distribution. Through the comparisons of the fracture propagation length, coalescence mode of the fractures and strength increase of the pre-cracked specimens under static and dynamic loading, the dynamic response of the fracture coalescence is found different with static loading under different geometric setting of the flaws. Furthermore, the inertia effect of the fracture propagation and coalescence is revealed under dynamic loading, that is to say, the growth of the secondary co-planar fracture and inclined fracture tends to the original propagation direction, and the immediate coalescence is taken place easily between two pre-existing flaws. But the fracture coalescence path is winding under static loading, which is different with dynamic loading. So, the inertia effect of the fracture propagation is regarded as the main cause of the strength increase of the brittle material under slow to medium strain rate. Moreover, the multiple coalescences among the flaws lead to the progressive failure for cracked specimens.