Study on the Characteristics of Strata Movement and Surface Subsidence Induced by Multiseam Mining

Multiseam mining generates enhanced characteristics of strata movement and surface subsidence (CSMSS) than single seam mining, which strongly increases the possibility of mine water disasters and surface deformation. In this study, the effect of seam separation distances and key stratum (KS) configurations on CSMSS is evaluated using the discrete-element method. The results of the analyses indicated that control function loss of the KS aggravated the failure of the overlying strata and expanded the original water-flowing fractured zone, which grew by 91.49% and 23.40% in short-distance and medium-distance multiseam mining. In addition, the subsidence was higher in the first two cases and also in the tilts and strains. The separation and penetrating tensile cracks determined the upper boundary of the caved and fractured zones in the discrete-element method simulation analysis supported by field data. Finally, this study provides a method for identifying the multiseam category according to the CSMSS resulting from multiseam mining operations, which is the first step toward effective disaster prevention and management.