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Utilizing tailings as aggregate and cementitious material to backfill underground mined‑out areas not only ensures mining safety but also enables large‑scale disposal of tailings solid waste. A thorough understanding of the effect of initial defects on the mechanical properties of cemented backfill can help optimize design while improving engineering safety and stability. This study employed the finite element software ABAQUS to numerically simulate the microstructural evolution of backfill materials. First, a model generation algorithm was used to construct two‑dimensional meso‑numerical models of cemented bodies with varying porosity. A convergence study on mesh size was conducted using pre‑inserted cohesive elements. Subsequently, displacement loading was applied to analyze the complete process from crack initiation to propagation in the numerical models. Finally, an in‑depth investigation of the stress‑strain curves was performed. The results demonstrate that: (1) with increasing porosity, both the number of fractured elements and the total crack length in backfill models under uniaxial compression gradually decrease; (2) when porosity increases from 0% to 1.5%, the compressive strength decreases by 18.6%; (3) although porosity influences crack initiation in backfill specimens, their ultimate failure processes remain similar. The numerical model was validated against experimental data from the literature, showing good agreement in both peak strength and stress‑strain behavior. This provides fundamental support for understanding the stability of tailings‑cemented backfill systems and offers a reference for more complex meso‑numerical studies of cemented backfill materials.

The escalating global "food-feed competition" and the drive for agricultural carbon neutrality have intensified the search for sustainable animal feed alternatives. Non-grain feed resources (NGFRs) — encompassing crop residues, agro-industrial co-products, and food waste — represent a vast nutrient reservoir. However, their direct application in monogastric and analogous aquatic animal diets is severely hindered by inherent physicochemical barriers, such as high lignocellulosic content, anti-nutritional factors (ANFs), and biosafety risks (pathogens and mycotoxins). To unlock the nutritional value of NGFRs, biological transformation has emerged as a highly efficient paradigm. This review systematically evaluates current bioconversion strategies, transitioning from standalone microbial fermentation and enzymatic hydrolysis to advanced insect-based bioconversion using the Black Soldier Fly (Hermetia illucens, BSF). Specifically, we highlight the disruptive innovation of the "multi-stage bioconversion system" multi-stage bioconversion networks. This synergistic approach not only accelerates fiber depolymerization and ensures profound detoxification but also maximizes nitrogen recovery and biomass accumulation. Furthermore, by integrating recent multi-omics data — spanning 16S rRNA sequencing, transcriptomics, and metabolomics — this paper elucidates the underlying mechanisms by which these upcycled resources modulate the "feed-gut-muscle" axis. Bioconverted NGFRs actively remodel the host's intestinal microecology, leverage AMPs for pathogen competitive exclusion, and significantly enhance terminal meat quality through improved antioxidant capacity and optimized lipid deposition. Despite scale-up challenges, current techno-economic and life cycle assessments confirm the long-term profitability of these integrated systems. Ultimately, the multi-stage bioconversion of NGFRs stands as a vital engine for achieving sustainable bio-manufacturing, ensuring global protein security, and fostering a circular bioeconomy.