Experimental research on influence of pipeline wear in high-density solid waste backfill

Pipeline wear is a crucial issue affecting backfill continuity and cost, and the situation of free-fall slurry with high-density coarse aggregate is even more severe. This work investigates the pipeline wear mechanism and its influencing factors through a self-made wear apparatus and thetical analysis. Results show that the high concentration (79–81 wt.%) slurry with coarse aggregate (maximum diameter of 13 mm) exhibits severe pipeline wear and damage, especially at the vertical section and bend area. Factors affecting pipeline wear are ranked from high to low: pipe material > aggregate size > slurry type > slurry velocity. Particle movement has three patterns in the free-fall system: suspension motion, jumping motion, and stacked particle pushing motion. Degree of wear is proposed from the prospect of energy consumption, which shows that pipeline wear has a positive relation with density, flow rate, and borehole height; it also has a negative relation with pipeline inner diameter. The research can guide backfill system design and optimization.