Impact of the Mining Dimensions on the Stability of Backfilled Pier-Columns

Owing to alternate mining of the new and old mining areas on sites, the mining thickness and width of the working face for pier-column backfilling varies. Thus, there is an urgent need to determine the impact on the bearing performance of the backfilled pier-column after changing the mined dimensions. This study consisted of three-dimensional numerical simulations, physical experiments, and field testing. These methods were performed to study the impact on the stability of the backfilled pier-column after changing the dimensions of the working face. The numerical and physical simulation results revealed that the mining thickness has a greater impact on the stability of the backfilled pier-columns than the width. Field testing results proved that the designed parameters for the backfilled pier-column in situ satisfy the bearing requirements; thus, it can effectively support the overlying strata of the goaf after mining. When increasing the mining thickness, the stress borne by the pier-column increased, and its stability decreased. Upon increasing the mining width, the variation in the stress exerted onto the pier-column was remarkably small, and the change of the elastoplastic zone of the pier-column was also minimal.