条形药包爆破预制贯通裂纹动态断裂过程研究

采用动态焦散线试验和ABAQUS数值分析方法，对条形药包爆破载荷作用下不同角度预制贯通裂纹的扩展行为进行了研究。研究结果表明：在爆炸应力波的作用下，柱部区域和端部区域0°预制贯通裂纹远端翼裂纹背离炮孔方向扩展，而近端翼裂纹朝向炮孔扩展。预制贯通裂纹远端的应力集中程度较近端高，并且远端翼裂纹的止裂韧度更低，翼裂纹更易扩展。在爆炸应力波的作用下，柱部区域90°预制贯通裂纹由张开逐渐转为闭合，爆炸应力波在已闭合的预制贯通裂纹面发生透射，并在预制贯通裂纹尖端产生压剪应力集中，形成以II型断裂为主的I-II复合型裂纹，并近似垂直于预制贯通裂纹面扩展，随后，在自由面反射应力波的作用下，反翼裂纹沿预制贯通裂纹面起裂扩展；炮孔端部区域90°预制贯通裂纹处翼裂纹的起裂是由于爆炸应力波在预制贯通裂纹处产生反射拉伸波的结果，促使预制贯通裂纹端部产生拉应力集中，形成近似I型裂纹，随后，翼裂纹逐渐转向爆炸应力波传播方向扩展。

Dynamic fracture process of a pre-crack under linear charge explosion

The dynamic caustic method and ABAQUS software were used to investigate the propagation behaviour of pre-cracks with different angles under the linear charge explosion. The results showed that when the pre-crack was 0°, the wing crack at pre-crack far-end initiated and propagated deviating from the borehole, but the wing crack at pre-crack near-end initiated and propagated toward borehole due to explosive stress wave. The stress concentration at the pre-crack far-end was higher than that at the pre-crack near-end, but the arresting toughness of the wing crack at pre-crack far-end was lower than that at the pre-crack near-end, and thus the wing crack was much easier to propagate. When the pre-crack angle was 90°, the pre-crack in the column area of the borehole gradually changed from open to close under explosion stress wave. The explosion stress wave transmitted through the pre-crack, then compressive-shear stress concentration and mode I-II fracture which was mainly mode II fracture appeared at the pre-crack tip. Then, the anti-wing cracks initiated by the reflection stress wave of the boundary of the model, and propagated along the horizontal direction. In the end area, the wing crack initiated by the reflected tensile wave of pre-crack, and tensile stress concentration at the tip of the pre-crack led to an approximate mode I fracture. Then the wing crack propagated gradually along the explosive stress wave propagation.