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Field Evaluation of Longwall Stress Distribution in Bump-prone Strata.
Paper in Proceedings of the 1992 :17 pages
How the geologic setting and dimensions of the underground workings of a retreat longwall influenced the stress distribution across the longwall face, active gob, gate pillars, and adjacent unmined panel was not fully known. At the VP No. 3 Mine of Island Creek Coal Company, the U.S. Bureau of Mines previously investigated the performance of a promising gate pillar design that decreased the potential of longwall face bumps. The longwall stress environment was further defined at this mine by measuring stress over two consecutively mined panels with Bureau-designed stress cells. The floor rock beneath two longwall panels and coal pillars in the gate road between them was instrumented. Panel and gob stress distributions were continuously monitored by a data acquisition system. Maximum stress was observed immediately in front of the longwall face, and a significantly greater portion of peak stress was imposed on the tailgate side of the current panel than on its headgate side. The pressure then quickly dropped as the face moved past the instruments. After the face passed, the center of the longwall panel regained significant overburden load; however, the instruments located less than 100 ft from the headgate edge of the panel showed little or no increase in pressure due to gob reloading.
Paper in Proceedings of the 1992 Longwall USA Conference. Maclean Hunter
Page last reviewed: April 12, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division