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A case study of grouted roof bolt loading in a two-entry gate road.

Signer SP; Jones SD
Proceedings of the 9th International Conference on Ground Control in Mining, West Virginia University, Department of Mining Engineering, Morgantown, West Virginia, 1990 Jan; :35-41
A field test was conducted by the U.S. Bureau of Mines at the Cyprus Plateau Starpoint No. 2 Mine, near Price, Utah, to study support rock interaction mechanics. Twelve instrumented, fully grouted roof bolts and eight sagmeters were installed in the roadway of a two- entry gate road to measure load changes and roof movements. Readings were taken during section development and as each longwall panel passed the test area. Loads that resulted from development of the entries were higher than would be expected if simple suspension of the roof rock was the sole cause of loading. When the first longwall face passed the test section, massive beam behavior was exhibited over the entry and adjacent pillar. However, no significant localized bending was detected at any of the strain gauge locations. After the first panel passed the test section, all the roof bolts had at least one zone where the steel had yielded. Loading continued to increase, and when the face from the second panel was adjacent to the test section, 70 pct of the strain gauges at the 6-, 18-, and 30-in locations had passed the yield point of the steel roof bolt. However, even at these high load levels, the supporting pattern was sufficient to provide adequate reinforcement to the mine roof.
Mining-industry; Underground-mining; Rock-mechanics; Ground-control; Ground-stability; Longwall-mining; Weight-factors; Case-studies; Height-factors; Coal-mining; Testing-equipment; Equipment-reliability; Mining-equipment; Weight-measurement
Publication Date
Document Type
Fiscal Year
Identifying No.
OP 130-90
NIOSH Division
Source Name
Proceedings of the 9th International Conference on Ground Control in Mining. West Virginia University, Department of Mining Engineering
Page last reviewed: March 11, 2022
Content source: National Institute for Occupational Safety and Health Education and Information Division