Analysis of the Interaction between Mobile Roof Supports and Mine Strata

摘要

Efficient and safe use of mobile roof supports (MRS) depends on the interaction between the MRS and coal strata. Of particular interest to this study are the mechanics of strata deformation as influenced by geologic conditions, pillar extraction methods, and MRS load-bearing capabilities. To provide a better understanding of the mechanics of strata deformation, the authors have collected and reviewed measurements of convergence and stress in one western U.S. mine and have completed pseudo-three-dimensional, boundary-element modeling for two typical pillar-pulling plans. Stress distribution in the mine roof above pairs of MRSs was calculated to demonstrate how MRSs contributed to the control of roof block movements. It was shown that overall stress and roof-floor convergence patterns were most influenced by the stiffness of coal-measure rocks and by pillar-pulling sequences and layouts. MRSs and other support systems play a critical role in controlling the stability of both the immediate roof and the middle roof for a distance of up to 18 m (60 ft) above the seam. MRSs provide unique ground control advantages over other types of secondary support by significantly reducing the time between mining and installation of secondary support. Although MRSs are similar to posts in stiffness and capacity, they are more effective than posts under static loads because they can yield and still maintain loads at near-peak capacity, whereas posts fail and loose their ability to limit mine roof deformation.