Investigation of the relationship between strata characteristics and longwall caving behaviour

This paper outlines the results of a study to analyse various longwall operations using the Geophysical Strata rating (GSR) to characterize the strata, assess the likelihood of weighting and then correlate this with the various outputs that can be provided by longwall support monitoring analyses. A significant advantage of integrating GSR and longwall datasets is to allow a 3D spatial understanding to be developed between strata characteristics and various support loading related parameters. A caving chart has been developed based on a combination of previous experience in longwall support assessment, strata characterisation, leg pressure data analysis and caving behaviour. The chart provides a link between strata conditions, stresses, panel layout and anticipated support loads via design thresholds that are related to roof convergence. The intent is to provide a means to assess the risk of cavities in the immediate roof and/or the risk of heavy weighting from the overlying roof units.