Assessing the efficiency of filters protecting base soil subject to erosion

Dams filters are mainly designed using filter criteria based on the grain size distribution (Sherard & Dunnigan, 1985). This paper reports experimental results obtained on the soil-filter system behaviour subject to different hydraulic and geometrical conditions. A silt soil and three sandy gravels were used as the core and different filters (F1, F2 and F3), respectively. The objective of this study was to determine the effectiveness of the filter to protect the silt submitted to erosion under controlled water flow (horizontal and vertical configurations). Particles transport and filtration through each granular filter were analysed as regards to filter retention capacity, particles size selection and grains shape. This study was achieved by conducting a comparison of the behaviour of the three filters against the silt erosion. A comparison of the efficiency of the filters is assessed toward the required usual relationship criterion and the most appropriate for the dam filters.