Impact of soil deformation on phreatic line in earth-fill dams

Generally seepage analysis and stress–strain analysis are conducted separately in the analysis of dams with varied water levels, which neglects the impact of soil deformation on seepage. The impact, however, is significant when the water level varies greatly. In this study, a simplified approach for consolidation analysis of unsaturated soil is used to conduct numerical simulations of water-filling in an earth-rock dam. Pore water pressure and phreatic line are simultaneously obtained in addition to stress and displacement within the dam. The computational results show that due to the coupling effect between deformation and pore water pressure, the development of phreatic line within the core-wall of the dam is quicker than that computed from unsaturated seepage analysis without coupling deformation. The variations of pore water pressure are related not only to unsaturated seepage induced by variations of water level, but also to the excess pore water pressure induced by deformation.