Investigation of drying and wetting effects on response of highly densified tailings to cyclic loadings: Shaking table test results

Abstract

In this technical paper, layered deposits of thickened tailings (TT) and paste tailings (PT) are first subjected to a period of drying, and then to manually simulated rainfall. Thereafter, the bottom layer of the deposits of TT and PT is subjected to shaking with the use of a one-dimensional shaking table. The pore water pressure and displacement are monitored at different depths of the layers. The obtained results show that excess pore water pressure at mid-depth of each layer of deposited TT and PT develops immediately until reaching the peak value during shaking. However, the excess pore water pressure ratio is smaller than 0.8 during shaking in the layered TT and PT deposits that are initially exposed to a drying and wetting cycle. In other words, these deposits did not liquefy during the cyclic loadings despite exposure to heavy rainfall. The excess pore water pressure ratio is smaller than 0.85 in the layered PT deposit (initially not exposed to a drying and wetting cycle), so this layer does not liquefy during shaking. However, the layered TT deposit (initially not exposed to a drying and wetting cycle) liquefies during the cyclic loadings. After the applied shaking loadings, the test results reveal that the layered TT and PT deposits initially exposed to a drying and wetting cycle resist post-shaking liquefaction while those not initially exposed to a drying and wetting cycle are susceptible to post-shaking liquefaction. Contraction and dilation are observed in all of the layered deposits during the shaking.