The influence of rock mass fracturing on splitting and contour blasts

ABSTRACT

Splitting and contour blasting are aimed to achieve suitable profiles by cutting along a surface, while common blasting is intended to detach and to fragment relevant rock volumes by increasing the fracturing state. These techniques are adopted in both underground works (tunnels, caverns, quarries) and also for surface excavations (quarries, mines, rock slopes engineering). Contour blasts are widely used techniques in mining and civil engineering to enhance performance while maintaining the safety of personnel and infrastructure. Splitting blasts are mainly used in dimension stone mining to obtain intact blocks of valuable ornamental stone. The parameters of controlled blasting (geometry, charge, blast agent) require an accurate selection using optimised blasting patterns and explosive properties; most of the proposed methods are limited and unsatisfactory due to insufficient consideration of rock mass properties. A quick but effective comparison and analysis of the different characteristics of the rock mass and its heterogeneities is presented, as it indicates a better strategy to determine a tailored blasting design for a given site, thus significantly improving the contour blasting quality.

KEYWORDS:

• Drill & blast
• contour blasting
• rock quality designation
• half cast factor
• over break

Acknowledgments

This work has been developed during the Project “ENERBLAST: Energy in Blasting and Comminution”, financed by Politecnico di Torino within the “Joint Project for the internationalisation of Research” program.

Disclosure statement

No potential conflict of interest was reported by the author(s).