Study on Effects of Water Drop for High Concrete Face Rockfill Dams in Narrow Valley

In order to analyze the influence of sudden drawdown of dam water level of high concrete face rockfill dam (CFRD), the paper took a narrow valley high CFRD project for example and conducted a comparative study of stress and deformation of panel and dam between different drop amplitude of dam water level. An elastoplastic hardening soil (HS) constitutive model was used to predict the behavior of CFRD. Then, through analyzing the calculation result of six calculation Cases, the paper summarized the effect of dam water level drawdown speed and amplitude on deformation and stress respectively of panel and rockfill zones. The results showed that owing to the arching effect of the CFRD in narrow valley, total deformation of concrete face slab occurring near the dam crest. However, the pressure and tensile stress of concrete face slab along the dam axial direction have a significant influence on the separation of the slab pieces, and potential seepage at the joints in the slab. The study indicates that the hardening soil model could better to analysis of the behavior of high CFRDs and to predict the performances of high CFRDs.