Rock mechanics investigations, design and construction of the Ridracoli dam

SummaryThe Ridracoli arch-gravity concrete dam is the major work in a multipurpose project whose main scope is the water supply to 37 communities in the Forlì and Ravenna Provinces.The particular geological and structural characteristics of the foundation rock mass, consisting of a rhythmical alternation of sandstone, silstone and marl, required a wide program of in situ and laboratory investigations in order to obtain a detailed physical and mechanical characterization of the foundation.The design criteria based on the use of a physical and mathematical model are illustrated as well as the limit equilibrium analysis of the stability conditions of the abutments. Particular attention has been devoted to the problem of the excavation stability; excavation methods and stabilizing works are illustrated in detail. The scepage problems are also presented with the description of grouting and drainage works.