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The effects of a retreating longwall on a three-entry gate road system.

Allwes RA; Listak JM; Chekan GJ; Babich DR
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 8996, 1985 Jan; :1-19
The Bureau of Mines conducted an in-mine case study on two consecutive three-entry gate road systems designed in accordance with the stiff-yield pillar design concept. This Bureau study was conducted in order to further develop technology that will improve the health and safety aspects of longwall mining. Support loading and strata activity were monitored to determine the effects of retreat longwall mining on the gate road ground control system. Analyses of pillar stress and roof bolt loading histories revealed that headgate roof support elements experienced cumulative loading throughout the life of the longwall panel. Tailgate pillar loadings had significantly different histories from the loading histories of the headgate pillars. Stress relief occurred in the tailgate pillars following the passage of the longwall face. Moreover, the stiff-yield pillar design, with the abutment pillar placed adjacent to the working panel when part of the headgate system, provided effective ground control in that no major roof falls or roof problems were experienced in the headgate or tailgate systems during longwall mining.
Publication Date
Document Type
IH; Report of Investigations
Fiscal Year
Identifying No.
RI 8996
NIOSH Division
Source Name
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 8996
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division