Mining Project: Assessing Elevated Stress Due to Full Extraction Mining
To develop engineering-based stress analysis procedures for improved assessment of stress-related hazards due to full extraction mining.
This project has five research aims, as follows:
- Determine the effect of gob development and resulting stress redistribution due to full extraction operations through field monitoring.
- Develop numerical models that can simulate stress redistribution and associated pillar and ground response resulting from full extraction mining, and conduct parametric studies to examine controlling factors.
- Determine the critical overburden and floor strength and stiffness relative to elevated stresses that drive dynamic failure(s) that leads to burst conditions.
- Develop a standardized procedure to predict the elevated stresses due to full extraction mining.
- Develop a rating scale for burst likelihood for coals in the US.
Dynamic rock and coal failures are a significant hazard during full extraction mining. These events are known as coal “bumps” or “bursts.” According to Mine Safety and Health Administration (MSHA) accident data, there were approximately 380 coal burst events reported from 1983 to 2013. Of those, 20 resulted in fatalities with 33% in longwall mines. There were two additional fatalities in a single event in 2014 during room and pillar retreat mining. The two most recent coal burst events that resulted in fatalities occurred in room and pillar retreat mining operations with distinct multi-seam interactions specifically at the accident sites.
Numerous research endeavors during the past 25 years have identified and implemented improved mine design and operational practices that have successfully reduced the rate of occurrence of burst events to the point where catastrophic events today are very rare. Nonetheless, the potential for such events and the ongoing challenge of prevention mandate that continued research be conducted to fully eliminate them.
This project’s research will use the best available geological data and improved identification of potential areas of elevated stress associated with full extraction coal mining to provide the most accurate risk assessment relative to full extraction mining, given current geotechnical practices in the US coal mining industry. Providing an improved picture of the stress regime will also enable future enhancements in geological characterization, which will be developed through other efforts to further refine the identification of conditions and mechanisms that control bursts and lead to further risk assessment enhancements. Ultimately these two research agendas—stress assessment and geological characterization—will combine to provide the best opportunity for developing prevention measures and avoidance forecasting designed to eliminate bump catastrophes. This project will primarily benefit research efforts related to coal bursts, but is also applicable to all ground control issues and may help to reduce other safety hazards in underground coal mining.
- 60 Years of Rockbursting in the Coeur D'Alene District of Northern Idaho, USA: Lessons Learned and Remaining Issues
- Comparison of Ground Conditions and Ground Control Practices in the United States and Australia
- Deep Cover Pillar Extraction in the U.S. Coalfields
- Determination of In Situ Deformation Modulus for Cemented Rockfill
- Dynamic Failure in Deep Coal: Recent Trends and a Path Forward
- Horizontal Stress and Longwall Headgate Ground Control
- The NIOSH Shield Hydraulics Inspection and Evaluation of Leg Data (Shield) Computer Program
- Numerical Model Calibration for Simulating Coal Pillars, Gob and Overburden Response
- Technology News 482 - Ground Support Safety Training Video
- Variation of Horizontal Stresses and Strains in Mines in Bedded Deposits in the Eastern and Midwestern United States
- Page last reviewed: 2/18/2016
- Page last updated: 2/18/2016
- Content source: National Institute for Occupational Safety and Health, Mining Program