Model Test and Deformation Analysis for Failure of a Loose Sandy Embankment Dam by Seepage

There are about 210,000 small earth dams in Japan that are important water resources for irrigation. Collapse of these dams induced by seepage due to heavy rainfalls occurs almost every year, since most of the dams are old and constructed of sandy soils with low dry densities. In order to investigate the behavior of the embankment dams during seepage, a large-scale model test was carried out. It was found from the test results that the embankment model showed a complex behavior combining shear deformations with saturation collapse. A simulation of the model test was conducted using saturated and unsaturated consolidation analyses with an elastoplastic model for unsaturated soils. The analysis simulated not only pore water pressures, deformations but also conditions of the failure of the embankment. Thus, the simulation results indicated that the method of analysis used here was suitable for estimation of behavior of embankment dams during seepage.