Stability analysis of dump with admixture of fly-ash and overburden material in open-cast coal mines

Abstract

Dump slopes with admixture of Fly-ash and overburden material for geo-mining conditions of mine A and mine B are simulated in FLAC SLOPE and OASYS software. Stability analysis of dump slope for mine B was carried out by field monitoring using total station and monitoring stations. For mine A, with addition of 15% fly-ash for a 30 m bench, the safe bench angle decreased by 20. This may be attributed to partial filling of the voids. With addition of 30% fly-ash, the safe bench angle increased by 10, which may be attributed to filling of void spaces. For the simulated conditions of 3 decks each of 30 m height, 280 angle and 40 m width of bench in mine B, the Factor of Safety (FOS) indicated through FLAC SLOPE for material with OB+25% fly-ash and layer wise dump construction are respectively 2.81 and 2.06. The difference may be because of reduction in unit weight in the former case. From the field monitoring data of Mine B dump, it is observed that the dump formed as admixture of fly ash and over burden material is stable.