Seepage Dynamics in Homogeneous Earthen and Rockfill Dams: Insights from Experimental Modeling Under Transient Conditions.

This study investigates the seepage behavior of homogeneous earthen and rockfill dams during transient conditions, focusing on the temporal variation in seepage discharge as influenced by material composition and structural characteristics. Using experimental modeling, seepage rates were analyzed over 200 minutes, revealing distinct patterns between the two dam types. For the earthen dam, the initial seepage rate was approximately 1 cm³/sec. This discharge decreased steadily over time, stabilizing at around 0.5 cm³/sec by the end of the observation period. The consistent decline reflects the lower permeability of earthen materials, which results in a controlled redistribution of water as the hydraulic gradient diminishes and seepage pathways stabilize. In contrast, the rockfill dam exhibited significantly higher initial seepage rates, starting at 2.5 cm³/sec due to its highly porous structure and larger void spaces that facilitate rapid water movement. Over the 200-minute observation period, the seepage rate decreased gradually, stabilizing at approximately 1.2 cm³/sec. This slower decline and higher stabilization point highlight the greater permeability of rockfill materials, allowing prolonged seepage flow before reaching equilibrium. The comparison of seepage dynamics underscores the impact of dam material properties on hydraulic performance under transient conditions. Earthen dams, with their steady reduction in seepage, are wellsuited for scenarios requiring controlled seepage management. However, the need for proper drainage systems to handle pore pressure buildup remains critical. Conversely, rockfill dams are effective at managing high initial seepage rates but may require additional seepage control measures, such as enhanced drainage systems or impermeable barriers, to ensure long-term stability and prevent structural compromise. These findings emphasize the importance of designing tailored seepage management strategies that account for the unique material properties and structural behaviors of each dam type. For earthen dams, measures to manage gradual seepage and stabilize pore pressures are essential, while for rockfill dams, addressing prolonged seepage flow and high initial rates is critical. This study provides valuable insights into the optimization of dam designs to enhance safety and efficiency, particularly under dynamic hydraulic conditions such as fluctuating reservoir levels or rapid drawdown scenarios. By highlighting the contrasting seepage behaviors of earthen and rockfill dams, this research contributes to the development of resilient and efficient water-retaining structures capable of withstanding diverse environmental and operational challenges.