Strength characteristics and stability analysis of GGBS stabilised fly ash-overburden dump

Stability of OB dump slope has been a major concern and require a proper design for safe mining operation. Utilisation of fly ash with OB material for construction of mine haul road and external dumping, may provide an alternative mode of fly ash disposal. In this study, fly ash was mixed with OB material at different percentages to evaluate the compaction characteristics, California Bearing Ratio (CBR), Unconfined Compressive Strength (UCS) and shear strength parameter. Tests were also performed with the addition of a different percentage of Ground Granulated Blast Furnace Slag (GGBS) with fly ash-OB mix. Further, the effects of GGBS at various curing period on CBR and UCS characteristics were highlighted. Numerical modelling was carried out for dump containing OB material, fly ash and GGBS at different proportions to evaluate the Factor of Safety (FoS) and to suggest the optimum dump geometry. Experimental result infers that maximum CBR and UCS values were obtained for 78% OB material, 10% fly ash and 12% GGBS at 28 days curing period. Based on the observed FoS from numerical modelling, an optimal multiple regression model and artificial neural network model have been suggested for the direct prediction of FoS by various input parameters.