Overtopping process and structural safety analyses of the earth-rock fill dam with a concrete core wall by using numerical simulations

Earth-rock fill dams are the most widely used dam type all over the world, and flood overtopping is the key reason causing dam burst. However, since an earth-rock fill dam with a concrete core wall is a modified new dam type, overtopping studies on these dams are rather deficient. The overtopping process and structural safety analyses of this new dam type have been studied in this paper by using a CFD-FEM coupled method based on the three-dimensional model of the Fangtianba reservoir expansion project. The scouring characteristics of the earth-rock fill dam, the variation trend of the downstream scouring depth, and the deformation as well as stress of the core wall have been obtained. Overtopping burst failure of the earth-rock fill dam with a concrete core wall is greatly affected by the downstream scouring depth, and tensile stress will occur on the upstream side of the core wall near the scour hole. When the downstream scouring depth is small and its growth is slow but stable, the tensile stress cannot exceed the allowable value in the early period of overtopping, and the concrete core wall may be able to support the dam body for a period of time, which might delay the occurrence of destructive collapse and overall burst. However, a sudden collapse may occur in the later period of overtopping; thus, reinforcement and emergency measures should be taken in time before the overall dam bursts.