Application of Haines and Terbrugge chart for suitable slope angles - a case study of artisanal and small-scale mining

Significant hazards in Artisanal and small-scale mining (ASM) are rock failure and slope collapse caused by overly steep pit walls, poor mine design and water pressure. There is a lack of expertise and capital in ASM. Providing a simple and cost-effective slope stability analysis and designing systems that can mitigate the risk of slope collapse is essential. This article aims to assess whether stability charts and estimations can be used to establish suitable slope angles to mitigate the overwhelming cases of slope collapse in ASM. The Bieniawski’s Rock Mass Rating system and Heins and Terbrugge stability chart were used to assess the stability of Small-scale mine slope and determine suitable slope angles. To validate the reliability of estimations, further analysis was performed through laboratory strength tests to find actual intact rock mass properties and create a model using OPTUM G2 to simulate the Hoek-Brown failure criterion. The study reveals that stability analysis using charts is applicable with the assistance of a rock engineering practitioner after exposing the intact rock mass to map discontinuities. The Heines and Terbrugge chart can be utilized to mitigate slope collapse in ASM, provided that the limitations of the stability graphs are recognized.