Evaluation of Surface Deformation Characteristics Over Longwall Panels in the Northern Appalachian Coalfield.
Proc Soc Min Eng AIME 1st Int Conf on Ground Control in Longwall Min Honolulu PP 183-198 :16 pages
Characteristics of surface deformations--i.e., subsidence, inclination, curvature, and horizontal strains--are evaluated, based on information obtained by direct field measurements over three longwall panels in the Northern Appalachian coalfield. Surface deformations were precomputed using bals' and knothe's theories. The results were compared with Bureau of Mines field data to evaluate the applicability of the two theories to U.S. mining conditions. Measured horizontal movements and the resulting horizontal strains differ as much as 300 pct from precomputed values. Topography has no detectable effect on vertical movements but appears to have substantial effect on the development of horizontal strains. The horizontal deformations computed from field measurements generally exceed the limits used in other countries to protect surface structures.
Proc. Soc. Min. Eng. AIME 1st Int. Conf.on Ground Control in Longwall Min. Honolulu, PP.183-198