A method for prevent water inrush from karst collapse column: a case study from Sima mine, China

Mining-induced groundwater inrush could result in serious economic losses and casualties. This disaster usually depends on geological structure, such as the karst collapse column (KCC). It could reduce the aquifuge thickness, causing a great risk of water bursting. In order to assess the impact of mining on the KCC, we have developed a complete set of methods, including three-dimensional seismic exploration, connectivity experiment, water injection experiment in two sidewalls, numerical simulation based on Drucker–Prager (D–P) elastoplastic damage theory. This method is used to test the size, type and the damage thickness of the KCC named DX1 in Sima mine, and the results indicate that the type of DX1 is good cementation. In addition, under the influence of the shear stress at the coal wall and the unloading at the goaf, a significant compressive damage zone with a large damage thickness will form at the sidewall of the KCC. As the roof collapses, the backfill is compacted and the maximum damage thickness gradually moves to the other side of the KCC. Eventually, an asymmetric inverted saddle-shaped damage distribution is formed with a maximum compression damage depth of 32.5 m. The results provide a basis for preventing water inrush from KCC.