Geomembrane barrier systems for construction and rehabilitation of embankment dams

Abstract

The main goal of this invited lecture is to discuss the use of geomembranes in embankment dams in order to understand and to evaluate the geosynthetic barrier function in different types of applications, both for the new constructions and also for the rehabilitation of existing dams. Presently, in more than 200 embankment dams worldwide, geomembranes are in fact the main waterproofing component, including the Contrada Sabetta rockfill dam in Italy, that dates back to 1959, being recognized from the international literature as the oldest geomembrane application in dams in the world. The use of geomembranes is generally associated with other types of geosynthetics performing various functions, as geotextiles for mechanical protection and local drainage, or also as geonets for more extended drainage, thereby forming a geosynthetic barrier system. In the invited lecture, the uses of geosynthetic barriers in the construction of new dams and also in the rehabilitation of existing dams around the world are critically reviewed. Design and construction aspects are considered, as well as selection and specifications of the various types of geosynthetic materials. In particular, the issue of sustainability matters on the use of geomembranes in embankment dams compared to the use of other traditional materials (as granular and cohesive soils, metallic blankets and bituminous concrete layers) is adequately treated. Finally, the durability aspects are extensively illustrated, with particular reference to the on-site behavior of applications in dams in the Alpine region.