Stress-strain state of the Yumaguzinsky hydroelectric dam

Abstract

Introduction. The stone-and-earth dam of the Yumaguzinskiy hydroelectric complex on the Belaya river is constructed in complicated geological conditions on heterogeneous foundation. The results of computational research of stress-strain state (SSS) of the dam, carried out for the variant of an earth dam with the central core are presented. When calculating the deflected mode of dams, the real structure of ground characterized by its relation of elastic and plastic bonds should be taken into account. The change of this structure takes place along with the change in stresses and is reflected in the values of coefficient of relative strength and coefficients of reliability. The values of the safety coefficients can be used to judge the strength state of the dam.

Materials and methods. The stress-strain state of the dam was determined on the basis of the energy model of the developed by L.N. Rasskazov. The area of the selected fragment of the dam has been divided into single-type elements; a triangular grid of the finite element method has been adopted, by means of which the structure of the soil dam and the foundation have been described.

Results. Numerical calculations have shown that when water level in the reservoir rises to the level of the forced retaining level the character of stress distribution σxx changes. At the base of uppermost buttress prism at the boundary with the core there appears an area with small positive values, the largest of which is obtained in the transition zone. The entire hydrostatic load is transferred to the pressure face of the core and, consequently, the entire work of external forces is transferred to the internal deformation energy of this element, causing a stress concentration in it. The transition zone material is forced to follow the deformations of the core, resulting in the development of tensile stresses in the core. Therefore, increasing the stiffness of the core results in less deformation of the core and correspondingly less tensile stress in the transition zone. The nature of stress distribution σyy is symmetrical.

Conclusions. Increasing the rigidity of the core entails elimination of the arch effect, which is particularly noticeable at lower reservoir levels. For this reason the use of skeleton material in the core of the dam is desirable.