Contact Analysis of Separation Between Concrete Slab and Cushion Layer in Tianshengqiao Concrete-Faced Rockfill Dam

Tianshengqiao concrete-faced rockfill dam (CFRD), with a maximum height of 178m, is the highest dam of the same kind in China and the second highest in the world. During the construction of the dam, some problems special for high CFRDs occurred, such as deficient of cushion layer and separation of concrete slab from cushion layer. In this paper, a finite element analysis is made to understand the deformation of the cushion layer and the separation between the slab and the cushion. Direct constraints method and Coulomb friction law are used to simulate the contact behavior between the deformable concrete slab and the cushion layer. The methods are shown to be effective through a comparison of the numerical results with in-situ measurements. The mechanism of occurrence of the separation between the slab and the cushion is discussed. Valuable suggestions are made for further design and construction of high concrete-faced rockfill dams