A study of the deformative properties of the rock foundations of hydraulic structures

Abstract

: 12The determination of the deformative properties of a rock foundation is an important stage in the study of the conditions of the joint behavior of a structure and foundation. Under full-scale conditions these characteristics are determined by static tests and seismoacoustic investigations. However, the results of these investigations do not always reflect the real overall deformative properties of the foundation. The relation between the results of dynamic and static investigations of the deformability of a rock mass is not always constant, which hampers the use of these data and an evaluation of the possible behavior of a structure with consideration of the real engineeringgeologic structure of the foundation.Model investigations of the static behavior of dams with consideration of the foundation structure, its deformative and strength properties have been carried out for a number of years at the department of hydraulic structures of the V. V. Kuibyshev Moscow Institute of Civil Engineering. We undertook the problem of investigating the use of static and dynamic methods of investigating the deformative properties of a rock foundation on models. In the first stage of these investigations we made a plane model of a foundation having a block structure (Fig. 1). This model (200 x 70 X 7 era) was composed of individual blocks measuring 7 x 7 x 7 cm laid up dry. The blocks fitted into one another on all adjacent sides, which ensured virtually no opening of cracks between them (the coefficient of friction of block against block was 0.60-0.65). Rigid fastening was provided about the stand along the contour of the foundation (displacements were equal to zero). The blocks were made of gypsum plaster-sand mortar, having a block modulus of elasticity 40,000 kg/em 2.During the investigations we made the following studies: a) evaluation of the static modulus of deformation of the base as a function of the size of the plate and magnitude of the external load; b) evaluation of the dynamic modulus of elasticity for different directions of action of the forces and as a function of the elevation of the reference plane; c) effect of the external load on the value of the dynamic modulus of elasticity; d) determination of the relation between the modulus of deformation and dynamic modulus of elasticity.