Present possibilities of studying foundations of concrete dams

Abstract

The paper presents the methods thought advisable for characterizing foundation rock-masses of concrete dams, the procedures to be followed and how to express the results for their application in the design.

The problem of characterizing the structure of rock-masses (Chap. 2), particularly the fracturing, is dealt with first, the important roles of geophysical methods in the first stage of characterization, and of integral sampling in the final stage, being emphasized.

Deformability is considered in Chapter 3, which, after a discussion of the sensitivity of concrete dams to changes in the modulus of deformability of the foundations, presents the principles advisable for characterizing rock-masses, the procedure recommended - especially the slot test which allows the characterization of large undisturbed volume, and the dilatometer test -, and finally discusses in detail the interpretation of the results of in-situ tests.

As regards the strength of the foundations (Chap. 4), the mechanisms of rupture and the concept of safety are discussed, and adequate testing procedures considering the scale effect are dealt with. The problem of strength characterization, especially by statistical methods, is also discussed.

Finally the advantage of knowing the initial state of stress in rock-masses is indicated (Chap. 5).