Cyclic shear response of fine-grained mine tailings

Abstract

The mechanical response of three different types of fine-grained mine tailings is examined using data from constant-volume cyclic direct simple shear (DSS) tests. Under cyclic DSS loading, fine-grained tailings typically exhibit a cumulative decrease in effective stress along with progressive degradation of shear stiffness. The observed shear strain development due to cyclic mobility is similar in form to that of the previously observed cyclic shear response for natural silts. The cyclic resistance ratio (CRR) of laterite tailings is observed to increase with an increase in the initial effective confining stress (σ′vc). For this material, the dilative tendency due to stress densification seems to have overridden the contractive tendency due to the increase in confining stress. In contrast, the CRR of copper–gold–zinc tailings is insensitive to the initial effective confining stress, suggesting a response similar to that of normally consolidated clay. The postcyclic maximum shear strength ratio (Su-PC /σ′vc) obtained from constant-volume monotonic DSS tests is noted to increase with a decrease in the void ratio. For the fine-grained tailings considered in this study, the liquefaction susceptibility predicted using commonly used empirical criteria is not always in agreement with the liquefaction triggering determined from cyclic DSS tests.Key words: tailings, liquefaction, cyclic stress ratio, postcyclic shear strength, direct simple shear testing.

Laboratory Investigation of the Resistance of Tailings and Natural Sediments to Cyclic Loading

“…8, it can be seen that the void ratio versus normalized cyclic resistance ratio data obtained by Sanin and Wijewickreme (2006); Wijewickreme et al (2005) and Ishihara et al (1980) fall within the established boundaries in the present study. The CRR results from Cyclic Direct Simple Shear (DSS) tests obtained from other researchers were transformed into an equivalent Cyclic Triaxial values using Eq.…”

“…Sitharam et al (2004) discussed the variation of normalized residual strength (i.e., with effective confining pressure) of soils with void ratio. Wijewickreme et al (2005) observed the variation of post cyclic maximum shear strength ratio with void ratio for two mine tailings. Peters and Verdugo (2003) showed the susceptibility of mine tailings to liquefaction and the need to further understand the response of tailings to cyclic loading.…”

“…This response can be determined from laboratory dynamic tests, such as cyclic triaxial test. A number of researchers have studied the response of soils, sediments and mine tailings to cyclic loading (McKee et al 1979;Ishihara et al 1980Ishihara et al , 1981Moriwaki et al 1982;Vick 1983;Poulos et al 1985;Alarcon-Guzman et al 1988;Marcuson et al 1990;Finn et al 1994;Koester 1994;Boulanger et al 1998;Yamamuro and Lade 1998;Braja et al 1999;Andrews and Martin 2000;Atukorala et al 2000;Thevanayagam et al 2000;Polito and Martin 2001;Youd et al 2001;Bouckovalas et al 2003;Bray et al 2004;Wijewickreme and Sanin 2004;Wijewickreme et al 2005;Hyde et al 2006;Leon et al 2006;Sanin and Wijewickreme 2006;Bouferra et al 2007;James et al 2007;Idriss and Boulanger 2008). For example, Ishihara et al (1980) showed that fine-grained tailings with a plasticity index of 15-20% have a smaller cyclic strength than those that exhibit non-plastic behavior.…”

Cyclic shear response of fibre-reinforced cemented paste backfill

“…According to Wijewickreme et al (2005), the preponderance of laboratory studies on mine tailings has not been performed using cyclic simple shear equipment and the studied stress paths therefore do not simulate the cyclic rotation of principal stresses that takes place during earthquake loading. Previous studies (Arthur et al, 1980;Wijewickreme & Vaid, 1993) showed that most soils experience deformations due to changes in the magnitudes of principal stresses and also to changes in their directions.…”

“…Previous studies (Arthur et al, 1980;Wijewickreme & Vaid, 1993) showed that most soils experience deformations due to changes in the magnitudes of principal stresses and also to changes in their directions. The variation of shear stresses under cyclic conditions along with changes in the direction of principal stresses is achieved during cyclic direct simple shear tests (Wijewickreme et al, 2005). Vaid & Finn (1979) considered the direct simple shear test as the most appropriate for the simulation of earthquake loading conditions.…”