Numerical study on spatial distribution of blast-induced damage zone in open-pit slope

Abstract

The excavation damage zone in rock slopes after drill-and-blast operations is of great significance for assessing the slope stability and design of open pit mines. The traditional method simplifies, the spatial distribution of the damage zone in a slope following blasting is as a single radius distributed, which leads to an inaccurate evaluation of slope stability. Herein, a model coupling the tensile damage and the Drucker-Prager yield criteria is established to investigate the spatial distribution characteristics of blast-induced damage zone in the final wall of an open-pit. Explosive explosion is converted to an equivalent pressure time history acting on the blasthole wall and the extension of the damage observed in the field test is reproduced successfully by numerical simulation. The proposed model is verified on the basis of the site-monitored data from the Wushan Copper mine, a large-scale open-pit mine in Inner Mongolia, China. The results show that the damage decreases with increasing depth, exhibiting a nonlinear distribution behind the slope face. The maximum depth and scopes of horizontal and vertical damage occur at the slope crest. The proposed model is compared with five widely used damage models and proves to be more capable of representing the spatial distribution of the damage zone observed in the site test. Finally, the formation mechanism of the maximum damage depth along the crest is also revealed.