Strength Characteristics and Stability Analysis of Ground Granulated Blast Furnace Slag (GGBFS) Stabilized Coal Mine Overburden-Pond Ash Mix

The increasing quantity of overburden (OB) removal and disposal in external dump needs proper management for active mining operation. Coal consumption in thermal plants generates huge quantity of pond ash thus, requires an alternative mode of ash disposal. In this study, attempt has been made to evaluate different geotechnical properties of OB-pond ash mix at various proportions. Effect of ground granulated blast furnace slag (GGBFS) on compaction characteristics, shear strength parameters, California bearing ratio (CBR) and unconfined compressive strength (UCS) value at different curing period has been presented. It was found that mix proportion containing 78% OB, 10% pond ash, and 12% GGBFS exhibited maximum UCS and CBR value at 28 days curing period. Stability analyses of dump composed of different proportions of OB material, pond ash, and GGBFS were carried out using numerical modelling to suggest the suitable dump profile. It was observed from numerical modelling that dump profile of 60.0 m height and 32° slope angle can be suitably adopted for all mix proportions. Based on the various input parameters, empirical model and multiple regression model have been developed to predict the CBR value and factor of safety respectively. Significance of various input parameters were analysed using sensitivity analysis and found that slope angle is highly sensitive parameters.