Skip directly to search Skip directly to A to Z list Skip directly to page options Skip directly to site content

NIOSHTIC-2 Publications Search

Search Results

Evaluation of multitimbered wood crib supports.

Authors
Barczak-TM; Tasillo-C
Source
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 9341, 1991 Jan; :1-11
Link
NIOSHTIC No.
10008551
Abstract
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.
Keywords
Crib-walls; Underground-mines; Coal-mines; Benefit-cost-analysis; Loads-forces; Stiffness; Deformation; Buckling; Test-facilities; Mechanical-tests; Underground-supporting; Structural-timbers; Supports
Publication Date
19910101
Document Type
IH; Report of Investigations
Fiscal Year
1991
NTIS Accession No.
PB92177377
NTIS Price
A03
Identifying No.
RI-9341
NIOSH Division
PRC
Source Name
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 9341
State
PA
Performing Organization
Corps of Engineers
TOP