Incorporating inherited variability into drainage effect analysis of piezocone tests in gold tailings

Abstract

The piezocone test (CPTu) is a commonly used field investigation method for analysing the geomechanical behaviour of mine tailings. However, the effect of drainage conditions on CPTu measurements is a critical factor in assessing tailings properties, particularly as tailings are often characterised as silty materials with intermediate permeability. Previous studies of drainage conditions have been hindered by the high variability of tailings materials, leading to considerable dispersion in experimental results. To address this challenge, the present paper proposes a numerical approach to characterise and incorporate the inherent variability of tailings to identify probabilistic limits of drainage. This approach involves characterising site statistics through piezocone tests and incorporating this variability into a set of Monte Carlo analyses using cavity expansion theory. The results indicate that the probabilistic analysis accurately represents the variability of the normalised resistance, although there is a greater discrepancy when considering pore pressure measurements. As a practical application, probabilistic values of cone resistance were used to establish profiles of fully drained and undrained tests. These corrected profiles can then be used in load capacity methods, providing rational limits of behaviour.