Ground control for highwall mining in the United States.
Int J Surface Min Reclam Environ 2005 Sep; 19(3):188-217
Highwall mining is an important coal mining method in the United States and may account for approximately 4% of total U.S. coal production. Highwall stability is the major ground control-related safety concern in highwall mining. Engineering away the safety risk by decreasing the highwall slope angle may be the best solution to the hazard posed by vertical joints in highwalls. The Mine Safety and Health Administration requires a ground control plan that usually specifies the hole width, maximum hole depth, maximum overburden depth, seam thickness, web pillar width, barrier pillar width, and number of holes between barriers. Design charts for these parameters are given. Web pillars containing preexisting auger holes are analyzed, and a design chart for estimating their minimum width is also presented. Close-proximity multiple-split highwall mining, which caused several serious highwall failures, is analyzed and recommendations are made. Finally, this study examined records from 5,289 highwall miner holes with a total completed hole length of 2.56 million ft to understand the reasons for early pullout. Average loss was almost 20% of planned hole length, and only 35% of the holes reached the planned depth.
Ground-control; Coal-mining; Safety-research; Injuries; Hazards; Highwall-mining; Slope-stability; Pillar-design; Geology; Rock-falls; Surface-mining; Geophysics; Accidents; Accident-statistics; Models
NIOSH Pittsburgh Research Laboratory, P.O. Box 18070, Pittsburgh, PA 15236
International Journal of Surface Mining, Reclamation and Environment