Granule structure influences on force chain development in the slag medium

Abstract

The slag dumps formed by mining activities are irregular granular media. Their particle size gradations are complex and granule structures are unstable.The stress between particles is transferred through the dependently unstable force chain. Taking the typical copper slag as the study object, its granule structure was investigated using CT scanning technology. According to plane compression and corresponding numerical simulation tests on coarse particles of different mass fraction contents, stress-straincurves, force chain evolutions and granule structure changes were obtained.Further, the synergistic effect between granule structure and force chain evolutionon macro-mechanics was discussed. Meanwhile, the compression law of granular material was revealed. The results show that the direction of force chain evolution direction inslag granular materialis consistent with the direction of pressure. The macro-compressive strength of slag increases first and then decreases with increasing coarse particle (>5 mm) mass fraction content and reaches the maximum compressive strength at the optimal coarse particle ratio of 50%. The granule structure and the soft-hard structure inforce chains have a significant synergistic effect. The granule structure change in slag granular material will experience three stages during compression process: the rapid compaction stage, particle crushing stage and stable compression stage. In the process of slag landfill, it is important to keep uniform filling and reasonable compaction to make it enter the stable compression stage, as well as controlling the optimal grading of coarse particles.

Keywords

• slag
• granular material
• granule structure
• force chain
• plane compression test