Analysis of Joint Parameters to Understand it’s Effect on Rock Blasting

Abstract

Rock mass consists of intact rock material and joints. Different joint parameters like orientation, spacing, persistence, aperture, infilling play important role in tunnel excavation. In drill and blast tunnel excavation, the propagation of blast shock wave differs from one rock mass to another rock mass based on their properties, because of which nature of rock fragmentation differs. All these directly affects the outcome of tunnel blasting. This study establishes the relationship between different joint parameters and excavation volume. In order to do so four different tunnel section of same tunnel alignment, with different joint properties were chosen and then collected data was processed to understand how different joint properties lead to different excavation volume within same tunnel. It was found that when the strike of the joint is parallel to the tunnel axis, the excavation volume obtained from blasting is comparatively higher than that when strike of joint is perpendicular to the tunnel axis, because when joints are parallel to the tunnel axis there is minimum reflection of blast wave from joint plane causing it to travel farther, increasing the fragmentation process. Shape analysis of blast fragments and natural rock block obtained from 3DEC was done in order to find the effect on fragmentation process. It was found that both blast fragments and natural rock block have similar percentage of different shape class proving fragmentation process during blasting of rock mass follows joint pattern, since they are the weak surface in rock mass. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.