The operation capacity of the construction of a rockfill dam with a concrete screen accommodated to the conditions of Pskemskaya HPP

Abstract

Introduction. A rockfill dam with a concrete screen is considered as an alternative to a traditional earth-faced rockfill dam in the process of designing a high-pressure Pskemsky hydraulic facility in Uzbekistan. A rockfill dam with a concrete screen has several strengths. However the geological structure of the dam site complexifies the application of a rockfill dam with a concrete screen, because dam boards have a deep layer of gritstone. There arose a need to study the stress-strain state of a 190 m dam in 2D and 3D settings. Materials and methods. The finite element method (FEM) and numerical modeling were employed to study the stress-strain state of the dam. The modulus of linear deformation of the rockfill top reaches 480 MPa, the one of the rockfill bottom — 240 MPa. The concrete deformation module was taken as equal to 29 and 12 hPa. The analysis took account of the isolation joint that separated the central part of the screen from its bank parts, while the contact surface of the screen and the dam body had a layer of friction-reduction emulsion. Results. The research performed by the co-authors enabled them not only to analyze the screen’s displacements and strains, but also to consider longitudinal forces and bending moments. Conclusions. A rockfill dam with a reinforced concrete screen has proven a reliable structure capable of accommodating static forces. However rock needs to be thoroughly compacted, and the water basin must be filled gradually. In this case, concrete compressive/tensile strength values will be sufficient in the 3D environment. The heterogeneity of the geological composition of the dam base cannot disintegrate the screen, because vertical joints compensate for the tensile stress arising inside.