Optimizing wood crib design: improving ground control and reducing support cost : T. M. Barczak & D. F. Gearhart, Engineering & Mining Journal, 195(12), 1994, pp 23–30

Abstract

Timber has been used as a mine support material for centuries because of its availability at low cost and favorable engineering properties. However, as the cost of timber continues to increase and as more difficult mine conditions are encountered, more efficient utilization of mine timber is required to improve ground control and reduce support costs. The U.S. Bureau of Mines in collaboration with Strata Products (USA) Inc. is conducting research to achieve these goals by developing engineering methods to optimize crib support design and employment. The most important design criteria is to maximize the crib stiffness while preserving the stability of the crib structure. This can be accomplished through the utilization of: (1) wider timbers, (2) more timbers per layer, (3) timber of a higher compressive strength, or (4) crib designs that employ parallel to the grain loading. There are practical examples of how to reduce support costs by tens of thousands of dollars without sacrificing support capability or mine safety by proper engineering of support systems. The focus of this article is to identify methods to improve timber utilization for mine roof support by utilizing: (1) proper engineering of conventional crib configurations; (2) multi-timbered crib configurations that employ moremore » than two timbers per layer; (3) concepts that employ parallel-to-the-grain timber loading; and (4) active crib loading. Practical examples of crib design and employment strategies to improve ground control and reduce support costs are provided.« less