Influence of Fines Content on Interpretation of the CPT Tip Resistance for Liquefaction Assessment in Mine Tailings

ABSTRACT: Liquefaction assessment of mine tailings is currently done using empirical correlations that were developed with data mostly collected in natural soils; their applicability to tailings is yet to be proven. In-situ density represented by the state parameter is the key link between liquefaction susceptibility and the Cone Penetration Test (CPT) measurements that are commonly used to characterize tailings. Quantifying the interdependence of gradation, in-situ state parameter, and CPT measurements is a first step in developing tailings-specific liquefaction assessment methods. In the current study, a tailings deposit comprised of silt and fine to medium sand was separated into its two enveloping particle size gradations. The gradations were then systematically mixed to identify the influence of particle size distribution on their properties. A series of triaxial compression tests were performed to determine how the friction angle, critical state line, and compressibility vary for each gradation. The results provide insights on the applicability of the fines content correction proposed in empirical CPT-based liquefaction correlations to silty mine tailings.