A triangular caving subsidence model

Abstract

Surface grounds undermined by longwall mining are potentially susceptible to subsidence due to continuous or episodic movements of the inter-burden and over-burden rock, particularly in the absence of any remedial measures such as fill or grout materials (for minimising subsidence). There are a number of methods available to predict or estimate subsidence. However, most methods introduced to the practical mining engineers are either highly empirical and site specific, or highly theoretical or impractical in terms of parameters to be used, measured or assumed. There is certainly a gap between these two extreme approaches for a geotechnical engineer who is looking for a simple practical analytical tool. Based on a triangular zone of major caving, beyond which arching and within which caving is dominant, this short paper presents a simple model for estimating potential maximum ground surface subsidence caused by underground coal mines and the required volume of remedial fill or grout (materials) for its reduction or prevention.