Numerical evaluation of affecting parameters of surface subsidence in abandoned mine areas

Surface subsidence in abandoned mine areas is a keen issue since it can cause loss of lives and serious property damage. However, the hazard of surface subsidence cannot usually be predicted in advance because surface subsidence is affected by many parameters. In this study, numerical simulation was carried out to predict the probability of surface subsidence. Many factors, such as cavity size, geometry, rock mass condition, rainfall and groundwater table, are well known for their key roles. Much research has been carried out to predict the probability of surface subsidence induced by the collapse or squeezing of a mined opening. In this study, the cavity geometry (i. e. depth, width, height and angle of cavity) and rock mass condition were selected as the key parameters for subsidence. A conceptual genetic cavity model in a horizontally layered rock mass was considered in the numerical simulation. The relationship between each of the selected factors and the hazard of subsidence was obtained. The vertical displacement observed at the ground surface with varying parameters was analyzed to evaluate their influences using a statistical method.