Strength Characteristics and Failure Mechanism of Cemented Super-Fine Unclassified Tailings Backfill

This experimental study investigates the strength characteristics of cemented super-fine unclassified tailings backfill (CSUTB) and its failure mechanism. Physical and chemical properties of tailings from the Zhongguan Iron Mine (ZGIM) were tested. A series of uniaxial compressive strength (UCS) tests was conducted to determine the relationships between UCS of CSUTB and three factors of cement-tailings ratio (CTR), solid content and curing time. Gray relational analysis (GRA) method was then used to study the sensitivity of UCS to these three factors. Results indicate that ZGIM unclassified tailings is a kind of alkaline super-fine tailings with high activity and quality. UCS of CSUTB increases exponentially with the increase of CTR and solid content, and increases linearly with curing time. The curing time is the most important factor for the UCS of CSUTB, followed by CTR and solid content. The stress-strain curves obtained from UCS tests show the failure process of CSUTB, including four stages of initial deformation, linear elastic, yield deformation and complete failure. It is the result of damage evolution.