Mechanical Properties of Soft Tailings from a Swedish Tailings Impoundment : Results from Direct Shear Tests

The shear strength of tailings can vary depending upon the type of ore and method of construction. Tailings dams may possess loose layers in subsequent layers, which may have low shear strength. Since the tailings dams are made-up to last for longer times, the strength parameters and material behaviors are essential to understand, especially potential for static liquefaction in loose layers. This article presents the results from direct shear tests performed on samples from loose layer of a tailings dam. Both drained and undrained tests are carried out. The results indicated the strain hardening behavior in tailings material which indicates loose condition. The shear strength was found to be relatively low as compared to typical values of tailings in literature. A contractant volume behavior was observed for all the tests. During shear tests the vertical height reductions in samples were observed. These changes were significantly increased after peak shear followed by slight increment in pore pressure along shearing angle. The reasons for these height changes are not fully known, but may be a rearrangement in skeleton or breakage of particles during shear which needs further investigative studies.Validerad; 2014; 20141008 (riabha)