Overburden stability of an inclined backfill stope in the context of the nonlinear elastic mechanical properties of the backfill body

Strata movement control during backfill mining of coal seam is dependent on the goaf filling rate, which is much related to the mechanical properties of the backfill bodies in goaf. A main roof mechanics model of the inclined backfill stope was established to investigate the factors that influence the overburden stability of an inclined coal seam during backfill mining. The proposed model was based on the results of laboratory tests on the compressive mechanical properties of crushed coal gangue and the key strata theory of ground control, which considers the nonlinear elastic mechanical properties of backfill bodies under a linearly increasing overlying strata load. The deformation characteristics of the main roof of the inclined backfill stope were analyzed in reference to the elastic thin-plate theory. The stability criterion of the main roof of the inclined backfill stope was inferred by introducing the Mohr–Coulomb yield criterion. And factors that influenced the overburden stability control of the inclined backfill stope were investigated. These factors included the elasticity modulus and thickness of the main roof, the overlying strata load, the advancement distance and workface width, the strata pitch of inclined stope, and the linear and the nonlinear foundation coefficients of the goaf backfill body. The results can provide crucial theoretical bases for determination of the sizes and filling rates of the goaf backfill body and the overburden stability control of an inclined backfill mining workface in coal seam under the actual engineering geological conditions.