Rockfill trenching for enhancing overburden dump height on weak soil strata

Dumping waste on weak soil layers can destabilize the dump, compromising its capacity for material disposal. This study focuses on the stability of dumps placed over weak black cotton (BC) soil strata in central India, with an emphasis on assessing the effectiveness of rockfill trenches (RFT) in improving dump stability. A combined approach using nine limit equilibrium methods (LEM) and the finite element method (FEM) was employed for analysis. The results demonstrate that dump stability is significantly influenced by the presence of weak strata under both dry and wet conditions when the dumping height is increased. The study also reveals that the factor of safety (FoS) can be enhanced by strategically placing an RFT near the toe of the dump. RFT width optimization for maximum stability was also carried out for increased dump height to 90 m. Moreover, the spatial arrangement of RFT beneath the dump can reduce displacement by 30–50%. The impact of RFT material properties on both FoS and displacement was examined, considering locally available materials. These findings suggest that careful design of on-site RFT dimensions can lead to substantial improvements in dump stability over weak soil layers.