Similar materials of colliery filling for physical simulation experiment

To study the interaction between the backfill and the overlying strata in paste filling mining, experiments were conducted on new similar materials of filling like raw materials of river sand, fly ash and cement, and the setting time and uniaxial compressive strength were main parameters. The optimal proportion of similar materials of filling was obtained by the uniform design method. Results show that there is a negative correlation between the uniaxial compressive strength of the similar materials of filling and the sand content and a positive correlation between the strength and cement content. The fly ash could not only reduce the setting time, but also could lead to a decrease in strength. The optimal proportion of river sand, fly ash and cement is 31 : 7 : 1, when the geometrically similar ratio is 1 : 100. Simulation test results using similar materials of filling prove that it could meet the experimental requirements.