Abstract
In Ontario, falls of ground and rockbursts are recognized as the main causes of deaths and serious injuries in underground mines. The traumatic fatal injury performance for ground control from 2000 - 2022 shows seven (7) fatal injuries recorded. Six (6) or 86% of the fatal injuries were associated with working at a heading face; five (5) or 83% were associated with seismicity and one (1) or 17% was associated with fall of ground. Undeniably, critical injuries have been associated with fall of ground and rockbursts in heading faces that should not be ignored for a goal to achieve ‘zero harm.’
The information contained in the reference material serves as a guide to assist mining operations to: (a) Develop a process of evaluating heading face stability advanced using drill-and-blast methods while considering the level of equipment/mechanization used and mining practices; and (b) Develop face support standards to be implemented based on identified and assessed potential hazards associated with the stability of heading faces and worker safety at the workplace, using face support design examples contained in this document as a guide.
The reference document provides a suggested flowchart for evaluating heading face stability. The evaluation process is intended to determine the requirement for face support based on the heading type, application, dimensions orientation depth, etc., the rock mass characteristics and failure mechanisms, type of equipment and level of automation used, and mining practices, among others. The design of face support is dependent on the condition of the heading face, and the timing of ground support installation in the development cycle depends on the level of equipment mechanization used in advancing headings with drill-and-blast processes.
Face support options are presented based on types of possible failure modes in low and high stress rock mass conditions in massive, jointed and heavily jointed rocks. The type of rock bolt to be used to tack the screen should be based on the stress/seismicity conditions of the rock mass and the degree of jointing. The Workplace Safety North (WSN) Ground Support Manual describes different ground support systems and rock bolt types that can be used for face support.