Mining Publication: Horizontal Stress and Longwall Headgate Ground Control
Original creation date: January 1998
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.
Authors: C Mark, TP Mucho, DR Dolinar
See Also
- AHSM - Analysis of Horizontal Stress Effects in Mining - 2.4.04
- Computer Simulation of Ground Behaviour and Rock Bolt Interaction at Emerald Mine
- Failure Mechanics of Multiple Seam Mining Interactions
- Global Trends in Coal Mine Horizontal Stress Measurements
- Horizontal Stress
- International Experience with Longwall Mining into Pre-Driven Rooms
- Multiple Seam Longwall Mining in the U.S. - Lessons for Ground Control
- Performance of Roof Support Under High Stress in a U.S. Coal Mine
- Stress Measurements for Safety Decisions in Longwall Coal
- Technology News 504 - NIOSH Releases New AHSEM and ARBS Software Programs to Improve Ground Control
- Variation of Horizontal Stresses and Strains in Mines in Bedded Deposits in the Eastern and Midwestern United States
- Content source: National Institute for Occupational Safety and Health, Mining Program