Research Specifications

A permeable zone inside the clay core of zoned earthfill dams may prevent the infrastructure from functioning properly. This paper aims to explore the influence of a defective permeable zone inside the clay core of an earthfill dam on the seepage functioning of the dam. The seepage behavior of an earthfill dam subjected to a weakness zone with various conditions and geometries is analyzed via numerical analysis. Then, the performances of some remedial works for rehabilitating a defective dam are investigated. According to the results, the occurrence of a weakness zone with a limited area inside the core does not influence the total seepage discharge through the dam body, and in turn, the hydraulic gradient in an adjacent intact part of the clay core increases to above 5, which may enlarge the defective zone. Furthermore, if a large area of the clay core from the upstream to downstream sides of the core becomes defective, the seepage discharge through the dam body is considerably increased up to 355 times greater than the intact condition. The performance of a remedial cutoff wall for rehabilitation of the waterproofing system of the dam depends on the interaction with the adjacent clay core. This type of interaction imposes an irregular shape in a phreatic curve and changes the hydraulic head regime at the upstream of the cutoff wall axis. Additionally, around the defective zone of the clay core, the remedial cutoff wall experiences a large hydraulic gradient up to 17.