EXPERIMENTAL INVESTIGATION OF SEEPAGE PATTERNS AND STRUCTURAL DEFORMATION IN EARTH-FILL DAMS

This paper presents a laboratory assessment of seepage behavior in the earth dam of the Qamashi Reservoir. A 1:100 physical model was used to examine water movement through a compacted loam dam body and to identify the development of the phreatic surface. The experimental results were also compared with field observations obtained at section PC16+30. The model was installed in a transparent hydraulic flume, while the upstream water level was kept constant at a value corresponding to elevation 487.68 m in the prototype. Changes in the wetting zone and the phreatic surface were monitored at five-minute intervals. Water temperature was 19.2 °C and water density was 999.6 kg/m³; the bulk density of the model soil was 1650 kg/m³. Seepage water appeared at the downstream side after approximately 41 hours. The model crest experienced 2 mm of vertical settlement, while the mean hydraulic gradient was 0.12. No visible soil washing, suffusion, or sudden deformation occurred during the test. The laboratory phreatic profile generally followed the trend observed in the field, although a noticeable difference occurred near the downstream toe because the model did not include the prototype drainage system. The results indicate that physical modeling can provide useful qualitative information about seepage development in an earth dam, provided that model simplifications and scale limitations are considered when interpreting the results.