Calculated and observed behaviour of clayey soil under cyclic loading beneath preloading embankments for oil tanks

Two accurately monitored preloading embankments built to reduce the settlement of two oil tanks for a thermo- electric power plant near Mantova, Italy, were analysed using the finite element method and different constitutive assump- tions. The most prominent feature of the proposed case study is that it involved two major loading cycles (preloading embankment construction–removal and oil tank filling–emptying) of different amplitudes (embankment heights of 8.60 and 12.50 m and a tank level of 14.00 m). Further minor loading cycles were also applied due to changes (of up to 6–7 m) in the hydrometric levels of the Po River. Because of the cyclic nature of the loading and the detailed measurements (of pore pressures and horizontal and vertical movements on the ground surface and in depth), this case study proves very useful for validating advanced features of modern constitutive models. The effects of elastic anisotropy, plastic anisotropy, and destructuration are considered in two different bounding-surface, kinematic-hardening plasticity models specific to clays and sands. The effects of permeability and Poisson’s ratio are also analysed. The conclusions have a general applicability and are not specific to the selected constitutive models.