Test on mechanical properties of solid backfill materials

Abstract

In this paper, characteristics that the overlying strata movement is controlled by solid backfill materials are illustrated in the coal mining with solid backfilling method. In addition, the mineral and chemical composition, density and moisture content of waste rock and fly ash are tested and analysed by physical–chemical treatment. By investigating the compaction deformation and time-dependence characteristics under different ratios of waste rock to fly ash, the optimal ratio of the mixture is obtained to achieve the smallest deformation, and results show that deformation mainly occurs in the initial period of loading. Combining the results of density test on site backfill materials, it indicates that the mass ratio of backfill materials to coal mining is 0·83 in order to ensure the effective of controlling the overlying strata in the coal mining with solid backfill method. The findings of the research provide references for the selection of solid backfill materials in coal mining.

Keywords:

• Backfill coal mining
• Solid backfill materials
• Mechanical properties
• Time-dependence characteristics

Acknowledgements

This work is supported by the Fundamental Research Funds for the Central Universities (Grant Nos 2013QNA27 and 2013RC01), and the National Key Basic Research Program of China (Grant No. 2013 CB227905).