Prediction of horizontal movement and strain at the surface due to longwall coal mining

• The ground monitoring data above longwalls in the Australian coalfields was analysed.
• Relationships were identified between the vertical and horizontal ground movements.
• The influence of surface topography was assessed using numerical modelling.
• Predictive equations were developed for the net horizontal movements at the surface.
• Relationships were identified between strain and the net horizontal movements.
• Predictive equations were developed for strain at the surface due to longwall mining.

Strain is an important parameter for assessing the potential for impacts on surface features due to mine subsidence. However, this parameter is also one of the most difficult to predict. Research is being undertaken with the objective to improve the currently available predictive methods for horizontal movement and strain at the surface. The methodology predominantly follows an empirical approach, using a large database of ground monitoring data, which was supplemented using numerical modelling. Predictive equations have been developed for the relative horizontal movements across various zones above longwalls based on the vertical subsidence and the influence of topographical features. These relative horizontal movements are then used as the basis to predict the distributions of strain within each of these zones. This paper provides an overview of the methodology and the current findings from this research project.