Development of predictive methods for strain at the surface due to longwall coal mining

Abstract

Longwall coal mining can result in impacts on natural and built features at the surface. The potential for impacts can be assessed using predicted mine subsidence parameters including strain. Improved predictive methods for strain have been developed as part of recent research using a large database of ground monitoring data from the Australian coalfields. Strain is predicted using a two-step process. Firstly, the net horizontal movements are predicted across each of the curvature zones above the active longwall. The distributions of strain are then predicted within each of these zones based on these net horizontal movements. The methods provide the site-specific predictions of strain anywhere above the active longwall based on the local surface topography, survey bay length and selected confidence level. The advantage of these methods is that they consider the potential for irregular anomalous movements, which are often not included in other existing predictive methods. The new predictive methods therefore can then be used to more reliably assess the potential for impacts on surface features located above longwall coal mining.