Analysis of energy dissipation characteristics and numerical simulation of surrounding rock control for backfill combinations with different ash-sand ratios

To reduce the economic cost of backfilling a mine, layers of cemented materials with different ash sand ratios are often used to backfill the void. In this study, we explored the damage evolution mechanism from the energy consumption point of view for backfill and rock combination with different ash sand ratios, and introduced the strength dissipation rate, damage value parameter and elastic strain energy rate to achieve the definition of damage in the specimens, as well as the characterization of the energy accumulation effect. In addition, the layered backfilling of the assemblage was simulated using FLAC 3D software. The results show that: (1) the elastic strain energy rate can reflect the accumulation ability of the strain energy of the specimen; the larger the strain energy rate, the stronger the accumulation ability; (2) the damage evolution of the backfill–backfill combination is divided into stages: initial damage repair stage, damage stable development stage, damage accelerated development stage and residual damage stage; and (3) the top layer with an ash/sand ratio of 1:4, the middle layer with an ash/sand ratio of 1:8 and the bottom layer with an ash/sand ratio of 1:10 is the optimal backfilling scheme. This study can provide a theoretical reference for the backfilling of a hollow area.