Geomembrane systems: 45 years history of the effective sealing of dams

摘要

Sealing systems with synthetic geomembranes have 45 years of service history. Based on the database that is currently under preparation within the International Commission on Large Dams (ICOLD), the authors present an overview of past and current applications. Geomembranes are synthetic materials, essentially impermeable, with two principal dimensions, prefabricated in the factory in the form of sheets; their purpose is to stop water infiltration. The use of synthetic geomembranes in the sealing of dams started at the end of the 1950s. The first reported applications were in the construction of new embankment dams as the impervious component to provide watertightness (1959, Contrada Sabetta, Italy, full face; 1960, Dobsina, Slovakia, full face; 1960, Terzaghi, Canada, at the toe). The concept of using synthetic materials instead of conventional materials such as earth or concrete certainly derived, among other considerations, from the good performance of embedded polyvinyl chloride (PVC) waterstops on the large number of concrete dams worldwide that rely on their use to stop water infiltration at contraction joints. A geomembrane system on the whole face can be considered, from a conceptual point of view, as one wide waterstop sealed at the abutments of the darn. Starting from 1971, geomembranes were also used for rehabilitation (Obecnice earthfill dam, Czech Republic and Lago Baitone gravity dam, Italy).