Application of Volumetric Runout Methods for Structurally Controlled Highwall Failures

Highwall failures in open cut coal mines are often structurally controlled. Such failures are often brittle in nature which elevates the safety risk for operations below, requiring accurate assessment of exclusion or standoff distances to prevent near misses or injury to plant and personnel. Runout estimation in the open cut coal industry is typically based on empirical methods. However, volumetric methods for runout estimation are used extensively in the hard rock mining industry. This paper reviews the applicability of these methods for structurally controlled highwall failures using case studies from BHP coal mine sites and literature. The findings indicate that volumetric methods are typically more reliable than existing empirical correlations and provide a method to quantitatively assess the failure consequence during wall optimisation.