Impact of Desiccation on Monotonic and Cyclic Shear Strength of Thickened Gold Tailings

2013 Colloquium of the Canadian Geotechnical Society: Geotechnical and geoenvironmental behaviour of high-density tailings

“…This behaviour is preserved in samples subsequently consolidated up to 400 kPa Daliri et al 2016). Similar trends exist in terms of cyclic loading (Al-Tarhouni et al 2011;Daliri et al 2014) and monotonic triaxial loading , whereby desiccation imparts a substantial increase in cyclic resistance ratio (CRR) or strength at a given void ratio. Notably, as shown in Fig.…”

“…The contribution of suction to strength requires that such suction not be dissipated in the tailing stack, e.g., during heavy rains. The stress history effects imparted to subsequently saturated and consolidated specimens by desiccation have been examined in the work of Al-Tarhouni et al (2011) and Daliri et al (2014, 2015, 2016, who imposed different stress histories with variable degrees of desiccation on gold tailings, using multiple methods of desiccation control, sample extraction protocols, and types of element tests (triaxial and simple shear). Other works on this topic include Cifuentes and Verdugo (2009), who partially investigated the influence of desiccation using triaxial samples obtained from a drying box.…”

“…Reid and Fourie (2012) have examined how the use of polymers in thickeners alters the strength characteristics of thickened tailings. Daliri et al (2014) imposed different stress histories (conceptualized in Fig. 10) on samples of gold tailings, using various methods designed to simulate the deposition process: samples were prepared at water contents (w) at likely high ends (w ϳ 38%, 70% solids) of density coming out of the thickener, and subsequently allowed to settle.…”

“…This suggests there is nothing inherent about the thickening process that eliminates the susceptibility of tailings to static liquefaction. If one takes stress paths of nondesiccated tailings from the simple shear tests reported in Al-Tarhouni et al (2011) and Daliri et al (2014), the collapse line (Sladen et al 1985) has a fairly unique angle of 15°-16°.…”

“…Figure 4 shows that the stable slope decreases as a function of impoundment size, but tends towards a finite value. For a shear strength of 0.5 kPa, corresponding to the postsedimentation shear strength of at least two nonsegregating gold tailings measured by slump tests and using a vane (Simms et al 2007;Daliri et al 2014), a stable slope of about 3%-6% is predicted.…”