Experimental investigation on compaction properties of solid backfill materials

Abstract

Authors investigate the compaction properties of five materials that are commonly used in the solid backfill mining technique, obtaining stress–strain, bulk-ratio–stress and strain–time relationships for each of them. The results indicate that all five materials undergo three stages during the compaction process: fast compaction, slow compaction and steady compaction. Although the stress reached 20 MPa in the experiments, for all five materials, most of the deformation occurred below 2·5 MPa. Deformation under constant stress generally accounted for only 2·62–8·5% of the total deformation. The authors conclude that a tamping force of 1·5–2·5 MPa should provide sufficiently dense backfill of the gob. The results of these experiments could provide the basis for selection of solid backfill mining materials and for control of the bulk ratio and of late-stage surface subsidence, thereby ensuring secure mining under buildings, railways or water bodies.