Characterization of a gold tailings with hypersaline pore fluid

A series of samples obtained from adjacent to piezocone penetration test (CPTu) locations within a gold tailings storage facility were tested to compare the inferred state parameter Ψ from CPTu results to the in situ density and critical state line (CSL) from reconstituted samples, and to assess the effects of salt concentration in the sample pore fluid on mechanical behaviour of the material. Preparation of samples with similar salt concentrations to those measured in situ gave CSLs that compared favourably to estimates of Ψ from the CPTu, in light of measured in situ density. Tests prepared without salt did not tend towards the same CSL as the salt samples, generally being at higher densities both following consolidation and subsequent shearing. These results are consistent with the observed effects of salt on mechanical behaviour in previous testing on clays. The implications and limitations of the testing program are outlined, and the need for further investigation of these issues is emphasised owing to the importance of tailings storage facility perimeter embankment stability.
Keywords: CPTu, critical state, salinity, triaxial