Experimental study on long-term load-bearing deformation and fractal characteristics of crushed gangue under dry-wet cycles

In order to study long-term load-bearing characteristics of gangue filling body in goaf under dry-wet cycles, creep test of crushed gangue was conducted by adopting self-developed large-scale deformation-seepage test system of crushed rocks. Effects of gangue lithology, axial load and particle size ratio on long-term bearing deformation, compaction and fractal characteristics of crushed gangue were investigated. Results show that under same axial stress, the higher the strength of gangue is, after compression, the smaller the creep deformation eigenvalues (compression quantity and strain), compaction eigenvalues (residual dilatancy coefficient and voidage) and fractal dimension are. Meanwhile, creep deformation eigenvalues and compaction eigenvalues decrease with the increase in wet-dry cycles. With the increasing axial stress, creep deformation eigenvalues and compaction eigenvalues of crushed gangue decrease gradually, while fractal dimension increases gradually after compression. Creep deformation eigenvalues of each wet-dry cycle decrease with the increase in wet-dry cycles. When n (Talbol power index) being 0.5, creep deformation eigenvalues and compaction eigenvalues of crushed gangue are the smallest, followed by the value when n being 0.7. However, creep deformation eigenvalues and compaction eigenvalues are the largest. At the same time, with the gradual increase inn, fractal dimension of crushed gangue after compression is larger. The fragmentation degree is higher. © 2020, Editorial Board of Journal of Mining & Safety Engineering. All right reserved.