Experimental investigation on the grading optimisation and storage effect of crushed gangue for backfill

Backfilling with coal gangue can effectively control gangue pollution and surface subsidence. In order to optimise the control effect of crushed gangue overlying rock, this article focuses on the regulating effect of gangue particle size grading on mechanical properties. Through research on the physical properties of gangue and natural graded gangue compaction experiments, the porosity of gangue and the process of gangue crushing are analysed. It is shown that the gangue material has good load-bearing performance. By storage analysis of the natural gradation experiments, the alarm height of the gangue was 20 m. Through compression experiments of group B, it was found that the particle deformation first increased and then decreased. By the analysis of particle strain energy density and breakage energy, it is concluded that the strain energy density of the sample from high to low is B1, B2, B6, A5, B5, B4, and the breakage energy to reach the sample state from low to high is A5, B6, B5, B4, B3, B2, B1, respectivley. The B6 group sample was found to have the best control effect on the overlying rock, thus providing suggestions for optimising the efficiency and effectiveness of backfill mining.