Abstract
Back-analyses have been carried out at 5 Australian longwall mine sites (10 longwall panels in total) to determine threshold values of critical leg pressure and convergence load cycle features capable of determining if roof control problems are likely to occur in advance. These threshold values were concluded to correctly predict roof cavities before they occurred approximately 80% of the time. This compares well with other rock mechanic empirical techniques. Threshold values were exceeded typically one–three shears in advance of cavities occurrence. This means that a pre-warning is possible in time for operational controls to be enacted that are aimed at preventing the roof control problems deteriorating to such an extent that the longwall has to stop production in the majority of cases.