Sequential Drawdown and Rainwater Infiltration Based Stability Assessment of Earthen Dams

Earthen dams supporting an upstream reservoir is always associated with the problem of seepage, as water seeks the path of the least resistance through the body of the dam as well as its foundation. Further, due to seasonal rainfall, rainwater can also infiltrate into the earthen dams. Depending on the rate and duration of rainwater infiltration, the stability of the dams is affected. The infiltration of the rainwater into the earthen dams results in the development of pore-water pressures and hydraulic gradients, thus altering the position of the phreatic surface within the embankment, causing consequent deformations. Thus, it is vital to assess the response of earthen dams to the duration and rate of rainwater infiltration during reservoir operating conditions. In this study, considering upstream drawdown conditions, the influence rainfall infiltration on the response of a homogeneous earthen dam has been identified. Coupled stress/pore-water pressure analysis has been carried out for this purpose. It has been observed that the pore-water pressures generated due to the rainwater infiltration adds to the seepage resulting in deformations of the dam faces and reducing the stability of the earthen dams.