Theory of stress-strain state of concrete faced rockfill dams

Abstract

In spite of the fact that concrete faced rockfill dams began to be used long ago; their designing is based on empirical approaches and there is still no common theoretical concept about peculiarities of their operation. With the aid of numerical modeling the author studied conditions of forming stress-strain state (SSS) of a concrete face with consideration of impact of various factors. The used methodology of analysis took into account operation of the face not as that of the plate but as a 3D structure interacting with the dam body in a complicated way. This permitted obtaining new knowledge about the face operation. It was revealed that friction farces at the contact of the face with the dam body play the main role in SSS formation. Due to friction the concrete face perceives not only deformations of cross bending but also longitudinal forces and deformations of longitudinal bending. The most dangerous is the face lower section where the face is subject to tensile longitudinal force and longitudinal bending, which may result in appearance of transversal cracks in the face. Considerable compressive forces perceive the face in the direction from the bank to the bank. The new theoretical concept about the concrete face SSS dictates reconsideration of approaches to designing of concrete face rockfill dams. For decrease of tensile longitudinal force, the pattern of rockfill zoning in the dam body should not allow considerable difference in deformation of the dam zones; also it is necessary to decrease friction on the contact of the face with the under-face zone. “Soft” vertical joints should be arranged to decrease compression in the face in the direction from one side to the other side.