Mining Publication: Short-Encapsulation Pull Tests for Roof Bolt Evaluation at an Operating Coal Mine
Original creation date: August 2003
The San Juan Coal Mine, located near Farmington, New Mexico, supplies the San Juan Generating Station with more than 6 million tons of coal annually. To replace dwindling surface mine production, San Juan installed a longwall in 2002. The roof rock in much of the underground reserve consists of interbedded coals, carbonaceous shales, and mudstones. Roof support consists of fully grouted roof bolts, both tensioned and nontensioned, supplemented by modified cable trusses. Short-encapsulation pull tests conducted by San Juan's geotechnical engineering department showed that some of the immediate roof layers provided variable bolt anchorage. To ensure that the roof bolts were obtaining the necessary anchorage, additional tests were done in a variety of locations. The results have been used to determine the optimum support design for different areas of the mine. Another series of tests evaluated the performance of several bolt and hole diameter combinations. The experience at San Juan Mine shows that short-encapsulation pull tests can provide the information necessary to improve ground control in variable roof conditions. It also illustrates how a proactive geotechnical engineering program can be an essential component of a state-of-the-art underground coal mine.
Authors: J Pile, S Bessinger, C Mark, SC Tadolini
Conference Paper - August 2003
NIOSHTIC2 Number: 20023433
Proceedings of the 22nd Intl Conf on Ground Control in Mining, Peng SS, Mark C, Khair AW, Heasley KA, eds. Morgantown, WV: West Virginia University, 2003 Aug; :226-232
See Also
- Analysis of Roof Bolt Systems
- Bolt Load Changes During Initial Face Advance and Cross-Cut Breakthrough
- Clay Veins: Their Occurrence, Characteristics, and Support
- Diesel Exhaust Aerosol, Review of Measurement Technology
- The Introduction of Roof Bolting to U.S. Underground Coal Mines (1948-1960): A Cautionary Tale
- Mistakes, Misconceptions, and Key Points Regarding Secondary Roof Support Systems
- Optimizing Secondary Roof Support with the NIOSH Support Technology Optimization Program (STOP)
- Performance Characteristics for Welded Wire Screen Used for Surface Control in Underground Coal Mines
- Preventing Falls of Ground in Coal Mines With Exceptionally Low-Strength Roof: Two Case Studies
- Zen and the Art of Rockbolting
- Page last reviewed: 9/21/2012
- Page last updated: 9/21/2012
- Content source: National Institute for Occupational Safety and Health, Mining Program