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Factors affecting strength and stability of wood cribbing: height, configuration, and horizontal displacement.
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 9168, 1988 Jan; :1-23
This report describes a study that investigates three parameters influencing the load-carrying capability of wood crib supports: height, configuration, and horizontal displacement. Four crib heights, four parallelogram configurations, and three ratios of horizontal-to-vertical displacements were tested on full-scale wood crib supports in a mine roof simulator. Test results indicated a reduction in load-carrying capability for increases in crib height. Increasing the contact area by changing the intersecting angle between crib blocks to form parallelogram configurations provided a slight increase in load-carrying capability for the first 10 or 12 in of vertical convergence, after which the cribs became more unstable, resulting in significantly less load-carrying capability. Horizontal displacements did not appreciably affect the load- carrying capability of wood crib supports for the range of vertical displacements (less than 10 in) likely to be encountered underground. This report documents these tests and postulates some explanations of failure mechanics for the observed behavior.
Field-tests; Coal-mining; Underground-mining; Roofs; Failure; Stability; Supports; Loads-forces; Rock-mechanics; Mines; Wooden-structures; Gateroad-supports; Passive-roof-supports; Roof-supports; Wood-cribbing
IH; Report of Investigations
NTIS Accession No.
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 9168
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division