Design parameters of roof support systems for predriven longwall recovery rooms.
2004 SME Annual Meeting, Feb 23-25, Denver, Colorado, Preprint 04-54. Littleton, CO: Society for Mining, Metallurgy, and Exploration, Inc., 2004 Feb; :1-13
Reduction in the recovery time required and improvements in safety during a longwall face move have compelled coal mine operators to examine and use predriven longwall recovery rooms. The recovery entry is developed at the longwall stop position and supported ahead of time so that the required combinations of standing and internal supports can be installed before the longwall face approaches. A calibrated three-dimensional finite-element model, developed in conjunction with an underground test area, provided the critical components and design principles for a comprehensive parametric study. The study shows that vertical, horizontal, and shear stresses concentrated on the outby abutment pillar corner of the recovery room, resulting in deformations in the immediate roof above the primary roof support anchorage level. The results of the numerical model and field site observations showed that the combination of the internal bolting system and the standing concrete supports are critical for the successful and safe extraction of the longwall equipment. Cable supports installed at an angle over the pillars can help stabilize the disturbed zone above the adjacent fender and outby pillars. However, standing supports are required in most sedimentary roof conditions to increase stability and ensure a safe longwall extraction.
Coal-mining; Underground-mining; Longwall-mining; Ground-control; Ground-stability; Geology
NIOSH Pittsburgh Research Laboratory, P.O. Box 18070, Pittsburgh, PA 15236
2004 SME Annual Meeting, Feb 23-25, Denver, Colorado, Preprint 04-54