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Horizontal stress and longwall headgate ground control.

Authors
Mark-C; Mucho-TP; Dolinar-D
Source
Min Eng 1998 Jan; :61-68
NIOSHTIC No.
20023834
Abstract
Horizontal stresses are caused by global plate-tectonic forces. During 1995 alone they were largely responsible for the closing of two longwall mines in the United States. This paper presents six case histories from Pennsylvania, West Virginia, Kentucky and Alabama. In each case, a mine encountered roof falls or difficult ground conditions at the headgate caused by horizontal-stress concentrations. The problems are detailed, and the control measures adopted are described. In most cases, nearby longwall panels without stress concentrations were trouble free. The paper also discusses detailed measurements that were made at two adjacent Pennsylvania longwalls One headgate was oriented to avoid a horizontal-stress concentration, and the other was not. Eliminating the stress concentration dramatically reduced roof support loads and roof deformation. The paper concludes that proper panel orientation and sequence is the key to maintaining headgate ground control. The optimum orientation is not parallel to the maximum horizontal stress, as previously thought, but rather it is 20 deg in the stress shadow of the gob. Other stress-control techniques, including artificial support, are briefly discussed.
Keywords
Mining-industry; Underground-mining; Rock-falls; Ground-control; Accident-prevention; Geology
Contact
NIOSH, Pittsburgh Research Laboratory, P.O. Box 18070, Pittsburgh, PA 15236
CODEN
MIENAB
Publication Date
19980101
Document Type
Journal Article
Fiscal Year
1998
NTIS Accession No.
NTIS Price
ISSN
0026-5187
NIOSH Division
PRL
Source Name
Mining Engineering
State
PA; WV; KY; AL
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