Geologic Models for Coal-Mine Roof Failures in Kentucky

Stephen F. Greb, James C. Cobb

Observations of underground coal mines in both of Kentucky's coal-fields are being gathered to better understand the geologic reasons for coal-mine roof failures. Collapses are classified on the basis of rock type, thickness, and geometry, as determined from observations of the fall debris and the fall scar.

Collapses occur (1) in shales with abundant plant-debris laminations, (2) in shales with high concentrations of coal streaks (rash) or coal riders, (3) in slickensided shales, (4) along bedding weaknesses in sandstones, (5) in thin interlayered rock types (stackrock), (6) where isolated rock features, such as kettlebottoms or concretions, occur, (7) where bedding is rotated or deformed, as in paleoslump features, and (8) where breaks caused by fractures and faults cut across bedding.

Geologic models based on these observations have been used to predict potentially unstable mine-roof conditions for a case study mine.

AAPG Search and Discovery Article #91031©1988 AAPG Eastern Section, Charleston, West Virginia, 13-16 September 1988.