In this study, dynamic photomechanical blasting experiments were conducted to investigate the interaction mechanisms of dual cracks induced by explosions at different relative positions. The experimental results demonstrate that both cracks penetrate when the actual relative vertical distance at which the crack tips begin to interact is within 10 mm in the experimental group; however, when it exceeds 10 mm, the dual cracks finally expand in a relatively parallel manner. The relative horizontal distance has a weaker impact on the final fracture mode. When the dynamic cracks begin to interact, both the propagation speed of the crack tips and the stress intensity factor increase, the crack propagation angle increases, and the crack propagation path exhibits curved characteristics. Based on the final fracture states of the specimens, the interaction results of the crack tips can be classified into three categories: deflection without merging, curvilinear merging, and parallel overlapping without merging. Based on the results of dynamic photomechanical experiments and the relative verification theory of the crack-tip stress field in previous studies, an expression for the stress-field distribution between dynamic crack tips during interaction was proposed. During the interaction of dynamic blast-induced cracks, the stress intensity at crack tips increases to 1.3–1.5 times that at the onset of mutual interaction. The cracks initially repel each other. As the relative positions of the crack tips increased, the local stress weakened, and the repulsion phenomenon diminished accordingly. Consequently, after crack interaction, the cracks exhibited a spindle-shaped pattern.

中文翻译：

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爆破载荷作用下两种动力裂纹相互作用机理的试验研究


在本研究中，进行了动态光机械爆破实验，以研究在不同相对位置爆炸诱发的双裂纹的相互作用机制。实验结果表明，在实验组中，当裂纹尖端开始相互作用的实际相对垂直距离在 10 mm 以内时，两个裂纹都会穿透;然而，当它超过 10 mm 时，双裂纹最终以相对平行的方式扩展。相对水平距离对最终破裂模式的影响较弱。当动态裂纹开始相互作用时，裂纹尖端的扩展速度和应力强度因子都增加，裂纹扩展角度增加，裂纹扩展路径表现出弯曲的特性。根据试件的最终断裂状态，裂纹尖端的相互作用结果可分为三类：挠度不合并、曲线合并和平行重叠不合并。基于动态光机械实验结果和前人研究中裂纹尖端应力场的相对验证理论，提出了动态裂纹尖端相互作用过程中应力场分布的表达式。在动态爆炸诱发裂纹的相互作用过程中，裂纹尖端的应力强度增加到相互相互作用开始时的 1.3-1.5 倍。裂缝最初是相互排斥的。随着裂纹尖端相对位置的增加，局部应力减弱，排斥现象相应减弱。因此，在裂纹相互作用后，裂纹呈现出纺锤形图案。