Laboratory Investigation of the Seepage Control Measures under Coastal Dikes

In the present study, the effects of seepage control measures under coastal dikes have been experimentally investigated. For the purpose of the study a laboratory model hydraulic flume 8.65 m long, 1 m deep, and 1 m wide was employed. The coastal dike was assumed as impermeable and made of a stainless-steel sheet of trapezoidal shape. The experiments were carried out employing five upstream and one downstream water levels. Besides, four different depths of sheet piles and four different lengths of impermeable blanket were used as seepage control measures. Results of the experiments were recorded at various points at the downstream foundation of the dike. The results indicated that the integrated application of two of the seepage control measures had more significant effect on reduction of uplift pressure. The results of the current study and two old empirical methods, that is Bligh and Lane, indicated that the Lane method underestimates the magnitude of uplift pressure and risk of piping in comparison with the Bligh’s method. Finally, the optimal values for impermeable blanket length and cut-off depth for minimizing the uplift pressure were determined.