Seepage Analysis of Concrete and Embankment Dam Abutment: A Case Study of the Ribeirão João Leite Dam

In the last decade, Brazil witnessed disasters relating to tailings dams. This led to changes in the National Dam Safety Policy, which regulates a set of measures to improve dam safety management. In this context, this paper presents a case study of the Ribeirao Joao Leite dam. The dam consists of a concrete gravity structure with embankment fill at both abutments, placed on a foundation composed of gneiss with quartzite veins. The study aims to investigate its seepage behavior and assess the performance of the seepage control system in the concrete and embankment cross-sections at the right abutment. Two-dimensional seepage analyses under steady-state and transient conditions were performed using the finite element method. A straightforward approach based on monitoring data was proposed to validate seepage analyses and estimate the efficiency of the seepage control system. It was concluded that the foundation of the dam has a significant influence on the pore water pressures and seepage flow behavior due to the presence of markedly fractured materials. The analyses indicated that the efficiency of the grout curtain in the right abutment foundation is not noticeable. On the other hand, the foundation drains play an important role in controlling pore water pressures throughout the dam foundation, even in unfavorable geological conditions. The efficiency of these drains was 28% at the drainage line of Block 2, preventing pressure increases of 36% in the foundation of Block 2 and 160% in the horizontal filter drain.