New Support Concepts for Hardrock Mining Applications

CIM Montreal 2007
Thomas M Barczak, Stephen C Tadolini,
Abstract A variety of support systems are routinely used in South African gold and platinum mines. Recently, several of these products have been adapted for coal mine applications in the U.S. as well. The purpose of this paper is to present an overview of this new support technology. A new roof support innovation in primary support is the Hydrabolt, which advances the technology of the Swellex-type friction anchor by maintaining water pressure in the tubing after the bolt is installed. This improves anchorage capacity by a factor of 2-3. Various standing support innovations have also been developed. These include pack type supports such has the Hercules crib. The Hercules crib is a timber pack that is a combination of cross grain and end grain timber block orientations that dramatically increases the stiffness of the pack over conventional wood cribbing. Various forms of both timber and steel construction prop-type support systems have also been developed. These include: (1) Propsetter, (2) Omni Prop, (3) Strata Prop, and the (4) Stro Master Prop. Prestressing of prop-type supports is commonplace in South African hardrock mines. Typically, this is done with a water-filled prestressing cell such as the Jackpot system marketed by New Concepts Mining. Prestressing, a focus of the paper, is considered essential to maintain support during and after the blasting of the mine faces. Heavy seismic activity is also present in these mines. All supports undergo extensive dynamic testing at loading rates up to 3 m/s to ensure survivability in this type of environment. This paper presents an overview of innovative intrinsic and standing supports that can provide improvements over existing designs over a wide range of loading conditions.
Keywords: Prestressing, Ground control, Timber, Support
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