Evaluation of multitimbered wood crib supports

Technical Report · Tue Jan 01 04:00:00 EST 1991

OSTI ID:6011146

Wood cribs are used extensively to stabilize openings in underground coal mines. This U.S. Bureau of Mines report describes the results of full-scale testing of several multitimbered wood crib configurations. Multitimbered configurations are wood cribs that are constructed with two or more timbers per layer. Nine different crib configurations were evaluated. Configuration parameters under study included the aspect ratio (height-to-width relationship) and the percentage of solid material used in crib construction. Test results and generalized wood crib behavior are discussed, and recommendations are made concerning crib constructions to maximize strength and stability. Crib performance is enhanced by reducing buckling effects by decreasing the aspect ratio and geometry considerations that increase the moment of inertia. A cost-benefit analysis of multitimbered wood crib configurations is made. Generally, increasing the percentage of solid provides more resistance at less unit construction cost. A comparison of laboratory results and underground observations of several wood pack wall supports suggests in situ load capacity is less than that measured in laboratory testing. Reasons for the apparent decrease of in situ load-bearing capability include load rate effects, stiffness of reaction surfaces, and varying boundary conditions that alter the load transfer mechanics of the crib structure.

• Research Organization: Bureau of Mines, Pittsburgh, PA (United States)
• OSTI ID: 6011146
• Report Number(s): RI-9341
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
012031* -- Coal
Lignite
& Peat-- Underground Mining-- Strata Mechanics & Control-- (1987-)
BOUNDARY CONDITIONS
COAL MINES
CONSTRUCTION
COST
MINES
MINING
NATIONAL ORGANIZATIONS
SUPPORT PILLARS
UNDERGROUND FACILITIES
UNDERGROUND MINING
US BUREAU OF MINES
US DOI
US ORGANIZATIONS
WOOD