After a long time operation, a conventional earth rockfill dam (e.g. homogeneous dam or core wall dam) may suffer from a lot of dam diseases such as dam-break, overtopping, landslides and leakage. On the basis of a large number of practices of rebuilding and strengthening the medium and small-sized dams, a new type of dam, a longitudinal reinforced rockfill dam, is proposed. This new type of dam has triple functions of seepage control, stress resistance and deformation resistance. It also has significant advantages in both construction material selection and construction technology when compared to a conventional earth rockfill dam. Based on the theoretical research and successful practice of the new dam construction technology by placing rigid structures (also called longitudinal reinforcements) in conventional rockfill dams, the factors of safety against overtopping compared with that of the unreinforced rockfill dams was briefly analyzed in this paper. The hydraulic process of the overtopping is presented, during which the downstream material is washed away and forming a scour hole in the dam. The progressive development of the scour hole will change the stress distribution of the reinforced body. Eventually the reinforced body will reach a state in which it is subjected to the pressure from the upstream when the toe zone is empty. The advantage of this new dam is that it changes the conventional overtopping failure mode to the progressive scour hole development mode, therefore delays the dam breaking, and provides time for repair and evacuation. The longitudinal reinforced rockfill dam has important and broad applications in the construction of new dams or strengthening of existing rockfill dams.
