Analysis and design considerations for superimposed longwall gate roads. Information Circular/1992 (Final)

The Bureau of Mines, in an effort to improve coal conservation and utilization is currently investigating longwall panel layouts to maximize coal recovery and minimize interactive problems in multiple seam operations. When longwalling coalbeds in descending order, the transfer of stress from overlying gate roads is a major design constraint affecting pillar stability in the lower mine. The lower mine gate road pillars must be properly designed to withstand the additional load transfer if gate roads are superpositioned in successive seams. The Bureau's MULSIM/NL model, which is a boundary element program, was used to analyze load transfer mechanics for superpositioned gate road pillars. Analysis of Longwall Pillar Stability, or ALPS, which is an empirically based design method for longwall gate road pillars, was used to calibrate model input parameters. This method provided a basis to verify model trends and recommend limits for safe pillar design when superpositioning longwall gate roads.