Seepage Analysis of Rock-Fill Dam Subjected to Water Level Fluctuation: A case study on Gotvand-Olya Dam

The Gotvand-Olya Dam is a rock-fill dam, located at Khuzestan province in southwest of Iran. Since the dam is subjected to the daily water level fluctuation, such as rapid drawdown and refill, thus induce astructural impact on the behavior of dam body, it draws many soil engineering concerns. In this paper, seepageanalysis of the rock-fill dam was primarily conducted to evaluate the dam safety against the leakage throughthe dam body. Traditionally, steady-state analysis was employed to investigate the seepage in the dam body,summing that water level is fixed at two cases: high and low water levels. Consequently, it was not able toproperly reflect the time-dependent characteristics of seepage phenomena. In this study, seepage analysis wasnumerically performed using 2-D FEM transient analysis. As a particular boundary condition for an analysis, the water level fluctuation was incorporated to simulate the daily changes. As a result, various seepage phenomena were quantified such as hydraulic gradient, seepage vector and pore water pressure distributionat the corresponding time of interest as the water level rises and recedes. At steady state analysis, the seepageflux at high water level in downstream area was predicted to be 78 l/s. In additions, the seepage flux measuredand estimated were both acceptable considering design criteria. The result of this study proves that there is no sign of hazardous sources contributing to the possibility of piping, internal erosion and excess leakage through the dam body.