| Abstract |
Over the past decade, the U.S. Bureau of Mines (USBM) conducted longwall gate road stability studies at four mines in the Book Cliffs and Wasatch Plateau Coalfields of Utah. These operations are characterized by multiple-seam mining, abruptly varying cover depths to 914 m (3,000 ft), and massive rigid sandstone units in the main roof or floor. Such conditions encourage severe bumping, roof instability, and occasional floor heave problems. Various gate road configurations have been employed to alleviate these problems. Though the mines have comparable basic conditions, lithologies and qualities of the immediate roof, floor, and seam are different in each mine, and often vary in a single mine. Gate road systems which mitigate hazards in one mine may prove inappropriate in another or for different areas of the same time. This report relates the geology of the coalfields; describes the location, geologic setting, specific mining conditions, operating history, and the USBM field study and results or conclusions for each mine; summarizes the relative performance of the gate road systems, and emphasizes the need for site-specific geotechnical data to evaluate gate road conditions and performance. |
