Analysis of influencing factors on the plastic zone width and stability of aeolian sand-based backfill strips

The stability of backfill strips is a central focus in strip backfill mining, as it determines both the design rationale and the applicability range of this mining technique. However, analytical approaches for evaluating backfill strip stability remain underdeveloped. In this study, a novel aeolian sand-based paste backfill material was developed using aeolian sand as the aggregate and alkali-activated fly ash as the binder. The resulting material exhibits high fluidity and substantial strength, offering a cost-effective and high-performance backfill solution for coal mining in aeolian sand-rich regions. A numerical simulation model for strip backfill mining was established, showing that the plastic zone width of aeolian sand-based backfill strips increases with greater mining height and depth but decreases with a higher area filling ratio. Through ternary linear regression, an empirical equation was derived to relate plastic zone width to these three parameters. By comparing the mechanical behaviors of backfill and coal strips and integrating A.H. Wilson's two-zone constraint theory with King's effective area theory, a stability expression for backfill strips was formulated for the first time. Field verifications demonstrated that the proposed stability analysis method for aeolian sand-based paste backfill strips is both rational and accurate, providing a reliable theoretical basis for engineering applications.