Study of dynamic stability of unsaturated embankments with different water contents by centrifugal model tests

It has been pointed out that the damage to unsaturated embankments caused by earthquakes is attributed to the high water content brought about by the seepage of underground water and/or rainfall infiltration. It is important to study the effects of the water content on the dynamic stability and deformation mode of unsaturated embankments in order to develop a proper design scheme, including effective reinforcements, for preventing severe damage. This paper presents a series of dynamic centrifugal model tests with different water contents to investigate the effect of the water content on the deformation and failure behaviors of unsaturated embankments. By measuring the displacement, the pore water pressure and the acceleration during dynamic loading, as well as the initial suction level, the dynamic behavior of unsaturated embankments with an approximately optimum water content, a higher than optimum water content, and a lower than optimum water content, are discussed. In addition, an image analysis reveals the displacement field and the distribution of strain in the embankment, by which the deformation mode of the embankment with the higher water content is clarified. It is found that in the case of the higher water content, the settlement of the crown is large mainly due to the volume compression underneath the crown, while the small confining pressure at the toe and near the slope surface induces large shear deformation with volume expansion.