Seepage through Rockfill Dams in Narrow Valleys

Abstract

Seepage analysis serves as one of the most significant stages in the design process of an embankment dam. In two-dimensional (2D) seepage analysis of embankment dams, little or no attention is paid to the seepage through side abutments. Moreover the role of grout curtain extensions into the side abutments and abutment material properties are inevitably neglected when performing a 2D seepage analysis. In this paper, two and three-dimensional. (3D) models of a rockfill dam during operation state are generated and several unsteady and steady state seepage analyses are performed using finite element method (FEM). The results obtained from 2D and 3D seepage analyses were compared with measurements from the instrumentation system installed in the dam body and foundation during construction. It is concluded that for embankment dams to be constructed in narrow valleys, 2D seepage analysis results are far from reality and considering 3D modeling of such dam sites is vital. Several design graphs were developed to calculate 3D discharge rates and hydraulic gradients from those obtained from 2D seepage analysis.