The mechanics of a silt-sized gold tailing

Tailing dam failures result in irreversible environmental impacts and cause fatalities. In recent years the mechanical behaviour of tailing geo-materials has received more attention by the geomechanics and engineering geology communities in an attempt to understand better their behaviour in the light of designing safer tailing dams. In this study, the mechanical behaviour of a gold tailing from Brazil is thoroughly investigated by conducting a series of compression and shearing tests as well as dynamic element tests. Fabric effects from the sample preparation method, the susceptibility to liquefaction and the possibility of any transitional behaviour are presented and discussed within a soil mechanics framework. Comparisons are made between the present gold tailing and previously published data on other tailings, giving a general view of the mechanics of tailings and the effects of grading. The results show that for this tailing the rate of convergence for different initial densities to the normal compression line is slow, and so the depositional density would affect the volume to far higher stresses than the material would be expected to experience in-situ. For this tailing any fabric effects from the sample preparation method were found to be very small to negligible with respect to small-strain behaviour and critical state behaviour. For different tailings, even if the particle sizes may cover a wide range, the susceptibility to static liquefaction, as determined by the location of the horizontal asymptote of the critical state line in the specific volume-log stress plane, shows no consistent variation. So it can be concluded that neither the pond nor the upper beach tailings are more susceptible.