Abstract: 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.

Key words: dynamic caustics method, ABAQUS numerical simulation, linear charge, pre-crack, crack propagation