The seepage behavior of a high concrete face rockfill dam on alluvium deposit

The nodal virtual flux method with a fixed finite element mesh is employed to investigate the non-confined seepage field of a high concrete face rockfill dam on an alluvium deposit layer after water impounding. Particular attention is also paid to the change of the seepage behavior caused by a local defect of the anti-seepage system located at the upstream side of the dam. The anti-seepage system considered consists of concrete face slabs, toe slabs connected with the grouting curtain in the dam foundation, and the seal system of the joints between the concrete slabs. For the intact anti-seepage system, the numerical results indicate that the seepage field is mainly concentrated in the dam foundation, and the location of the phreatic surface in the dam body is very low under normal conditions. Once a crack in the slab or a local failure of the concrete joint seal occurs the seepage behavior of the dam changes significantly. The concrete face slabs, joint seal and the sufficient depth of the grouting curtain are the significant anti-seepage barriers to control the seepage behavior of the dam, and particular attention should thus be paid to these elements for the design and construction of concrete face rockfill dams.