Remediation of a hazardous legacy slope face using pre-split blasting

Abstract

Effective engineering characterization of granites altered through processes of kaolinization is critical for safe extraction and design of slopes for the china clay industry in south-west England. This case example describes the remediation undertaken to alleviate the significant hazard associated with a 26m high legacy slope within an operating china clay pit. Remote rock mass characterization of the hazardous slope was undertaken using terrestrial laser scanning from numerous set-up locations to provide geo-spatial data for blast design, kinematic analysis and subsequent instability analyses. The trial pre-split blast resulted in a reduced overall slope angle and sufficient space for design of a suitable rocktrap, thereby reducing the risk to acceptable levels when following a Rockfall Hazard Appraisal System (RHAS). The trial also provided useful guidelines for future use of the technique, particularly for implementation when considering controlled blasting when approaching final pit wall limits.