关键词: 水布垭面板堆石坝, 垫层, 渗透变形, 试验

Abstract:

The height of the concrete faced rockfill dam (CFRD) of Shuibuya hydropower Station is up to 233 m. The properties of the cushion material are very important for the dam deformation & seepage control. Based on the CFRD construction experiences of the world and the test results at feasibility study of Shuibuya Projects, the function of the cushion layer and the design requirements for its materials are discussed. The permeability and seepage deformation characteristics are pivotal among the design requirements. A series of seepage deformation tests on cushion material performed further at construction design stage are expounded. Permeability, critical and failure hydraulic gradient from horizontal model tests are higher than those from corresponding vertical model tests. Horizontal models simulate better the situation of filling and flow pattern in the cushion layer of the real dam. So the results from horizontal models approach more closely to the properties of the cushion layer. With different gradation curves and density values, the permeability varies in a large range. It is mainly between 10-4-10-2cm/s as required, but the coarser materials with low density would exceed the upper permeability limit. The critical and failure gradient does not changes so regularly as gradation curve and density varies. The interior structure of the material would not be stable. The results emphasize further the importance to control the material gradation and filling density. The seepage stability of the cushion layer must be supported by the transition zone with efficient filtering and protection.

Key words: Shuibuya Concrete Faced Rockfill Dam, cushion layer, seepage deformation, test