No abstract

The application of numerical methods for calculating the interaction of hydraulic structures and foundations by means of digital computers is ~esently acquiring ever greater importance for engineering practice. Such a method, which is new being developed successfully in a number of countries and permits solving static and dynamic problems for complex inhomogeneons systems, problems of percolation, thermal stresses, etc., is the finiteelement method. Publishing in this issue the articles by S. B. Ukhov and by S. V. Tolkacheik, Ya. I. Natarius, and G. A. Leshkevich, the editor hopes to attract the attention of readers to the use of finite.-element method for joint calcuiation of hydraulic structures and foundations. The editor points out to the readers that the first publication devoted to the application of the finite-element method for the calculation of stresses and strains in earth dams was contained in the article of V. D. Liam Finn and A. P. Troitsldi in the sixth issue of our journal in 1968.The finite-element method is based on the classical variational principle and is applicable for solving a wide range of problems: calculations of the stresses and strains in inhomogeneous and nonlinear systems (from the physical and geometric viewpoints), percolation and temperature calculations, calculations of the effect of dynamicloads, etc. The possibilities of the method are practically unlimited and are determined only by the capacity of computers. Therefore, considerable attention is presently being paid to theoretical and applied investigations of the finiteelement method throughout the world [1].In the USSR application of the finite-element method to the solution of certain problems of hydraulic engineering is being investigated. Many of the studies pertain to calculations of earth dams [2][3][4]. The monograph of L. A. Rozin [5] is the most complete of the studies published in the USStL

In full-scale investigations of the rock foundations of high-head dams, the dynamic methods (ul=asonic, seismic) of measuring the deformation indexes have found wide application. The dynamic modulus of elasticity E d of a rock, which is obtained by the dynamic methods, does not by itself define the deformability of a mass subjected to the action of forces comparable to the loads which the structure exerts. In the analysis of the combined action of the structure and the foundation, use is made of the "static moduli of total deformation" E s, which are determined by applying loads through plates or by subjecting to compressive loads the walls of the rock excavations. However, these tests have many deficiencies, which have been frequently noticed by many investigators.The development of mobile, relatively simple and cheap methods of dynamic measurement, permitting the investigation of the deformability of significantly larger volumes of rock masses than with static methods, has made necessary the establishment of the true relation between the magnitudes E d and E s. Attempts to establish this correlation experimentally have been made by several authors [1-3].The basic condition affecting the accuracy of an investigation conducted on the correlation between E d and E s is the independent study of the dynamic and static methods as applied to equal volumes of rock representing the same conditions. The techniques for applying the dynamic and the static loads are rigorously defined. In the investigation of the relations and the interpretation of the test results, direct and indirect correlation may be used. The most promising approach is the indirect correlation jointly with the attempt to establish the physical relation between the different links. The order in the investigation of such a relation may be as follows: a) the relation between the dynamic and the static moduli of elasticity of the rock, E d and E e, is established. The static modulus of elasticity E e is determined by analyzing the loading or unloading branches when the sample is under the action of the equivalent-instant loading;l" b) the relation between the static moduli of elasticity E e and the static moduli of total deformation E s is established. The determining factor in this relation is the fissuring of the rock; c) on the basis of the types of relations indicated above, by using values characterizing the degree of dissipation of the impulses produced by the elastic vibrations on the rock (which is a function of the texture of the medium which characterizes its non-elastic properties, in the first place the fissuring), the relation between the dynamic moduli of elasticity E d and the static moduli of total deformation E s is established.However, the experimental data gathered up to now permit presenting results obtained by direct correlation which show good agreement and which have been established by the authors by using five types of rocks corresponding to the sites of the Andizhansk and Kirovsk reservoirs. The evaluation of this correlation, whi...

The wide increase in construction on rock foundations requires that engineers develop and perfect methods for calculating stresses and strains in rock foundations interacting with the structures. This problem is especially acute in connection with the construction of large hydro installations, for the design of which are solved such important problems as slope stability, stability of the rock masses surrounding tunnels, and determination of stresses and strains in tunnel linings, and in the foundations and bodies of high dams.

No abstract