Mining Publication: Use of Ground Penetrating Radar and Schmidt Hammer Tests to Determine the Structural Integrity of a Mine Seal
Original creation date: February 2002
Over the years, more than 20,000 mine seals have been erected in underground coal mines in the United States. Seals are used extensively in underground mines to isolate worked-out areas, active mine fire zones, and to control water inundations. Seals are most often built directly in the mine and can be fabricated from blocks made of wood or cementitious material. Recently, several explosions occurred within sealed areas of underground U.S. coal mines. These explosions, believed to be initiated by lightning strikes on the surface, destroyed numerous seals and caused considerable damage external to the sealed area. The National Institute for Occupational Safety and Health is conducting research to develop design guidelines, to investigate noninvasive techniques to characterize seal strength properties, and to evaluate seal test methods. As part of this work, a 30-ft wide, 16.1-ft tall and 4-ft thick seal was built in an underground experimental mine using cement and foamed water. Two types of noninvasive techniques are currently being investigated, namely the Schmidt Hammer for measuring compressive strength and ground penetrating radar (GPR) for detecting the presence of anomalies (e.g., voids, discontinuities) within the seal. Once these noninvasive tests were completed, the seal was subjected to destructive explosion testing. This study presents the results of the Schmidt Hammer tests, GPR scans, and the characteristics of seal failure during explosion testing.
Authors: MA Trevits, WD Monaghan, GL Mowrey, MJ Sapko, RA Thomas
Conference Paper - February 2002
NIOSHTIC2 Number: 20023426
Symposium on the Application of Geophysics to Environmental and Engineering Problems (SAGEEP), Las Vegas, NV, February 10-14, 2002. Denver, CO: Environmental and Engineering Geophysical Society, 2002 Feb; :1-14
See Also
- Compendium of Structural Testing Data for 20-psi Coal Mine Seals
- Designs for Rapid in Situ Sealing
- Designs for Rapid In-Situ Sealing
- Evaluation of Mine Seals Using Ground Penetrating Radar
- Experimental Mine and Laboratory Dust Explosion Research at NIOSH
- Explosion Pressure Design Criteria for New Seals in U.S. Coal Mines
- Passive Mine Blast Attenuators Constructed of Rock Rubble for Protecting Ventilation Seals
- Progress Toward Improved Engineering of Seals and Sealed Areas of Coal Mines
- Structural Analysis and Design of Seals for Coal Mine Safety
- Use of a Sodium Silicate Gel Grout for Plugging Horizontal Methane-Drainage Holes
- Page last reviewed: 9/21/2012
- Page last updated: 9/21/2012
- Content source: National Institute for Occupational Safety and Health, Mining Program