Design of a Controlled Blasting Operation for the Removal of an Unstable Rock Mass from a Rock Slope

Summary

Abstract

Explosives remain a highly effective technique for rock-face remediation (slope clearing and stabilisation) when safety, geometric flexibility, and certainty of detachment are critical. Explosive techniques allow remote or rope-assisted operations where direct access is unsafe, typically requiring lower specific explosive consumption than production blasting due to variable free-surface conditions. The design approach emphasises precise drill-hole positioning, static criteria for detachment charge sizing, and controlled confinement to achieve clean, damage-free niches that prevent subsequent instability. Simultaneous initiation is often preferred in irregular or non-repetitive layouts to reduce the risk of charge exposure or incomplete detonation. Key safety considerations include ensuring effectiveness at first attempt, maintaining a minimum safety clearance of 500 m in unfavourable topographies, and preventing blast-induced overbreak. This paper presents design principles and operational guidelines for controlled blasting in remediation works, focusing on confined-charge configurations, timing strategies, and safety optimisation. A rock-slope remediation project case study is presented, in which the proposed controlled blasting methodology was applied. The case shows the method’s effectiveness in achieving stability, minimising overbreak, and ensuring operational safety under challenging field conditions. The paper contributes practical recommendations to enhance the reliability and safety of blasting-based remediation in complex rock slopes.