Two practical examples of numerical approaches for solving discontinuity problems in dam design

This paper draws attention to the great influence certain types of discontinuities in foundation rock masses can have on dam design. By means of two practical examples, the role of numerical procedures in the solution of stability and deformation problems posed by foundation heterogeneities is discussed and emphasized. Some basic theoretical considerations regarding the limit‐states and the concept of safety to be used in dam design are also presented as a complement to the analyses description. The case of the Ãgua Vermelha dam, recently built in southern Brazil, is the subject of the first example. Here, a major joint in the basaltic foundation was the decisive geological feature for the stability analyses which were performed by means of the finite element method. The second example refers to the Itaipu dam, a record‐breaking Brazilian–Paraguayan hydroelectric development. Marked sub‐horizontal discontinuities between lava flows, greatly reducing the strength and stiffness of the basaltic rock masses, were of main concern in this case. The results of the foundation studies, with due help of numerical procedures, called for the construction of concrete shear keys, in order to achieve a satisfactory margin of structural safety.