Movement behavior of rock strata in multi-level sublevel filling mining and forecasting of differential surface subsidence

• Propose a dynamic alternating expansion mechanism of "pressure-relief arch" and "load-bearing arch" under multi-midsection mining, revealing nonlinear stress superposition and energy transfer patterns. • Identify three distinct disturbance zones (direct, superimposed, potential sliding) governing overburden failure via tensile-shear crack activation and stress arch evolution. • Compare interval vs. continuous mining: interval methods limit deformation to <150 m with wave-like stress transfer, while continuous mining induces <220 m deformation via progressive stress redistribution. • Establish stope layout-pressure transfer correlations: interval mining yields wider asymmetric subsidence (0.14m@40 m depth), continuous methods concentrate higher subsidence (0.29m@40 m) with reduced spatial spread. • Develop a predictive framework integrating arch mechanics, disturbance zoning, and subsurface displacement thresholds for backfill mining safety optimization. To address issues such as ground pressure manifestation, rock beam fracture, and overburden displacement caused by multi-level sublevel filling mining of gently inclined medium-thick ore bodies, this study adopts the Fankou Lead-Zinc Mine as the engineering background. Through a combination of numerical simulation and theoretical analysis, it systematically reveals the movement behavior and the mechanism of surface subsidence of the overburden under the disturbance of multi-level sublevel filling mining. Mechanical models of the stress “pressure relief arch” and “bearing arch” are established, along with a mechanical model of the filling body and roof under combined disturbance effects. The results indicate that multi-level sublevel filling mining induces nonlinear superposition effects in the stress unloading-loading cycles. The disturbance of adjacent stopes induces an alternating development pattern of “pressure relief arch” and “bearing arch”. The activation of potential slip surfaces under combined disturbance is a key controlling factor contributing to asymmetric surface settlement. The disturbance zone can be divided into three types: a direct disturbance zone influencing the settlement magnitude of the overburden; a compound disturbance zone that alters the transmission pattern of mining-induced stress and the height of the stress arch; and a potential slip zone prone to shear and tensile failure. The stope layout pattern significantly influences the transmission pattern of mining-induced stress and the disturbance range. Under the intermittent mining mode, the overburden experiences uneven deformation within a height range of less than 150 m, whereas under the continuous filling-mining mode, uneven deformation extends to a height of up to 220 m.