Аңдатпа
Integrated large-scale direct shear tests and discrete element method (DEM) simulations were used to evaluate basic oxygen furnace (BOF) slag as a sustainable partial replacement for natural crushed-stone ballast. Laboratory tests provided validation targets for a specific BOF source under low confinement (30–70 kPa), while DEM reproduced the gradation and angular shapes using clumped particles. The simulations were calibrated to the measured shear stress–strain curves and then used to probe micromechanics, including coordination number, strong/weak contact partition, and fabric anisotropy. Across 0–100 % BOF by volume, peak shear strength and peak friction angle decreased with increasing BOF; however, mixtures with 20–40 % BOF retained performance only marginally below natural stone. Microstructurally, BOF addition reduced coordination and peak fabric deviator, shortened force chains, and increased contact-orientation randomness—features that explain the strength reductions. A compact pre-peak constitutive relation between fabric deviator and stress ratio, ϕ d = a ( τ / σ n ) b , provided excellent fits for the overall and strong contact networks. These results offer mechanism-based guidance for mixture design: limited BOF substitution (20–40 %) provides a practical balance supporting material -circularity potential while maintaining shear capacity within a narrow penalty band. The study demonstrates how DEM-informed fabric metrics, interpreted alongside large-scale testing, can support the adoption of industrial by-products in railway ballast without compromising key mechanical requirements.