Abstract
As mines go deeper and get larger, mine designs become for many reasons more fragile, and ground control and rock support increasingly become significant levers in construction schedule and in production performance. Ground control with effective support becomes a strategic element of asset management. This investment must be protected and maintained to reduce the risk of ground related production disruptions. This article provides an overview of guiding principles for an operational approach to ground control in deep mines.
Several interlinked concepts are important when assessing the health of an excavation. Design concepts must not only account for load equilibrium but also for deformation compatibility. Most importantly, it must be understood that the support’s displacement capacity is being consumed when the rock mass is deformed after support installation. It is necessary to design for the remnant support capacity at the time when the support is needed, i.e. at a critical stage of its utility. This often-dominant aspect in mining is ignored in standard empirical classification systems for support design and has led to unnecessary damage, the need for support repair and production interruptions.
This article focuses on support design for brittle ground when displacements induced by stress-fracturing consume much of the support’s capacity. It deals with the functionality of the support in deforming ground, with the consequences of mining-induced support damage (e.g. during production). If support capacity can be consumed, it can also be restored by means of preventive support maintenance (PSM). This concept for cost-effective ground control is introduced and illustrated on operational evidence. Furthermore, it is discussed how design can impact construction costs and schedule. Accounting for capacity consumption and integrating preventive support maintenance into the mine development and operation schedule provide opportunities for prudent asset management. From a technical perspective, this means that rock must be made self-supporting.