Function relational expression of backfilled body’s density and its influencing factors

Abstract

ABSTRACT Filled body is the main carrier for restraining overburden strata movement in solid backfill mining, and degree of restraint is strictly controlled by density of backfill body. Through 3D model of backfill body compacted by backfill support, main factors influencing density of backfilled body during backfilling and compacting process are analyzed, the function relational expression of backfill body’s density is established, the mechanism of dense backfill body changed from loose materials through compaction is revealed, namely, density is determined by factors of backfill technology, including pileup height, tamping angle, tamping times, backfill equipment, backfill materials, geological conditions, and other influence factors. When backfill equipment, an especial geological condition given and backfill material selected, higher pileup height, more tamping times and larger variation range of tamping angle result in larger density. The engineering practice of Chengjiazhuang Coal Mine shows: the function relational expression of backfill body’s density is ρ = ρ 0(4.94 + 1.85h d − 0.15β + 0.16n)/(h·d·k), so when coal mining height (β) is 2.8 m, width of support (k) is 1.5 m, backfill web width (d) is 0.6 m, initial density of backfill body (ρ 0) is 1.35t·m−3, pileup height (h d) is 1.822 m, natural repose angle (β) is 42°, tamping times (n) is 5 (variation range of tamping angle is 3.0–29.6°), the density of compaction forming of gangue (ρ) is 1.71t·m−3, and backfill body’s compression ratio is controlled over 91%.