The influence of desiccation and overconsolidation on monotonic and cyclic shear response of thickened gold tailings

摘要

Regulators are naturally concerned with remobilization of unbounded deposits of mine waste residuals, such as thickened tailings stacks. Consequently, the monotonic and cyclic behaviour of thickened tailings is of significant interest to practitioners of mine waste geotechnique. Thickened tailings are known to gain strength through a combination of hindered settling, desiccation, and consolidation post-deposition. This paper reports on the effects of over-consolidation ratio (OCR) and desiccation, using a simple shear apparatus (NGI type). Samples were alternately overconsolidated by either mechanical loading, or by desiccation followed by rewetting and consolidation. Mechanical overconsolidation highly influenced the monotonic and cyclic resistance of thickened tailings specimens and both monotonic and cyclic resistance exponentially and continuously increased with increasing OCR for desiccated tailings, the relationship between increasing OCR and increasing cyclic resistance is more complicated and, surprisingly, could be converse with excessive desiccation beyond the shrinkage limit.