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Evaluation of polyurethane injection for beltway roof stabilization in a West Virginia coal mine.

Molinda GM
Proceedings of the 23rd International Conference on Ground Control in Mining, August 3-5, 2004, Morgantown, West Virginia. Peng SS, Mark C, Finfinger GL, Tadolini SC, Heasley KA, Khair AW eds., Morgantown, WV: West Virginia University, 2004 Aug; :190-196
Extremely difficult ground conditions were encountered in the main belt entry in a room-and-pillar mine in West Virginia. Several generations of supplemental support, including cable bolts, cribbing, and Heintzmann jacks and beams, failed to halt roof falls that threatened workers' safety and the life of the mine. Polyurethane (PUR) was injected into 27 intersections in the roof, and the results were monitored by borehole video camera. The mine had averaged two to three falls in the beltway per year. Since the roof injection, no roof falls have occurred. Pre- and post-injection monitoring of test holes showed that stability can be achieved without filling all of the existing void spaces. Video logging showed that the project goal of building a beam from 2 to 6 ft into the roof was successful. Preinjection monitoring of roof fractures uphole can delineate the zones to target for reinforcement and avoid pumping PUR into large voids to little effect. Multiple-injection zones can be identified, and the entire intersection drill hole array can be optimized based on knowledge of the fractured zones. In addition, premonitoring can prevent excessive hydrofracturing in solid zones. Polyurethane injection is a proven method of rock stabilization in even the weakest, most broken ground. Optimization of the injection design by preinjection video diagnostics can greatly contribute to successful and efficient roof stabilization.
Ground-control; Coal-mining; Safety-research; Underground-mining; Room-and-pillar-mining; Injury-prevention; Accident-prevention; Engineering-controls; Control-technology
NIOSH Pittsburgh Research Laboratory, P.O. Box 18070, Pittsburgh, PA 15236
Publication Date
Document Type
Conference/Symposia Proceedings
Peng SS; Mark C; Finfinger GL; Tadolini SC; Heasley KA; Khair AW
Fiscal Year
NIOSH Division
Priority Area
Research Tools and Approaches: Control Technology and Personal Protective Equipment
Source Name
Proceedings of the 23rd International Conference on Ground Control in Mining, August 3-5, 2004, Morgantown, West Virginia
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division