Abstract: In this study, based on the 250 m grade concrete face gravel dam of Dashixia in Xinjiang province, large-scale direct shear tests were conducted to determine friction parameters of the interface, and numerical model considering the contact effect was established. The influence of contact effect on stress and deformation of the dam body, concrete slab, and water stops were studied. Results show that the hyperbolic model can meet the non-linear relationship of the shear stress and the displacement of the interface. If the contact effect is not taken into account, the deformation gradient and the principal stress value of the dam body become low, and the arch effect would be overestimated. The deflection and the slope direction stress of slab are less affected by the contact effect, while the axial displacement and the axial stress are greatly influenced. The deformation of the peripheral joint is strongly affected by the contact effect. Under the high-water pressure, the local dam body slip may occur, which may lead to an increase of the peripheral and vertical joint deformation. The results of this study and in-situ observations of Anchicaya dam reveal that the control of peripheral joint deformation is the key point in constructing concrete-faced rockfill dams in steep valleys.

Key words: steep valley, concrete-faced rockfill dam, friction contact, direct shear test, finite element