Contour blasting

Contour blasting is a technique employed in underground mining and tunnel to achieve a smooth contour of underground openings, minimizing rock mass damage and overbreak. Article studies the mechanics of stress redistribution around the future opening, emphasizing its role in blast-induced fracture development. We demonstrate that understanding stress redistribution can significantly impact the design of an effective blasting pattern. The article presents analytical and numerical models that clarify principles of contour blasting to achieve a smooth contour without necessary increase in drilling. Before the detonation of contour charges, the maximum principal stress aligns closely with the shape of the underground opening, significantly affecting the length and orientation of blast-induced fractures. In this context, the ratio between the maximum and minimum principal stresses plays a crucial role in designing an effective burden for the contour charges.