A laboratory investigation of the dynamic properties of tailings

The dynamic response of tailings from a gold mine located in western Quebec was evaluated using cyclic laboratory testing. These tailings are classified as non-plastic silt and sand. Specimens of the tailings were prepared as slurries, consolidated to vertical effective stresses of 100--400 kPa, and subjected to cyclic direct simple shear testing with cyclic stress ratio, CSR, values between 0.075 and 0.15. The shear modulus reduction of the tailings under cyclic loading was found to be fairly similar to that described for clean sands in the literature. The cyclic resistance ratio, CRR (which reflects the liquefaction resistance), of the samples was not significantly affected by the effective consolidation stress (in the range considered here). Analysis of test results with the simplified method of liquefaction evaluation indicates that this method may be applicable to these tailings. However, other factors, such as the possible effects of layering and ageing of the tailings in situ, should also be considered in such an assessment. Key words: tailings, dynamic behaviour, liquefaction, shear modulus, cyclic direct simple shear test. Le comportement dynamique des residus miniers d'une mine d'or de l'ouest du Quebec a ete evalue a l'aide d'essais cycliques de laboratoire. Ces residus sont de la classe des silts et sables non plastiques. Les specimens ont ete prepares a partir d' une boue, consolides sous une contrainte verticale effective de 100 a 400 kPa, puis soumis a des essais cycliques en cisaillement simple sous un rapport de contrainte cyclique (CSR) entre 0,075 et 0,15. La baisse du module de cisaillement des residus sous chargement cyclique est semblable a celle rapportee dans la litterature pour des sables. Le rapport de la resistance cyclique (CRR), qui reflete la resistance a la liquefaction des echantillons n'a pas ete affectes de facon notable par la contrainte de consolidation (pour la plage consideree ici). L'analyse des resultats avec la methode simplifiee d'evaluation de la liquefaction semble indiquer que cette methode serait applicable a ces residus miniers. Toutefois, d'autres facteurs, comme la stratification des materiaux in situ et leur vieillissement, devraient etre pris en compte lors de telles analyses. Mots-cles : residus miniers, comportement dynamique, liquefaction, module de rigidite, essai cyclique en cisaillement simple. [Traduit par la Redaction]
Introduction Tailings are one of the primary waste products of mining operations. They are made of fine-grained particles of the parent rock from which the ore is extracted by crushing, [...]