The Geomembrane Facing Rockfill Dam (GFRD): an advantageous proven system to construct safe dams

Alberto Scuero¹; Gabriella Vaschetti¹; José Machado do Vale¹

¹ CARPI TECH

Baixar PDF doi:10.20906/CPS/CB-03-0003

Resumo

Polymeric geomembranes, having a permeability some orders of magnitude lower than traditional water barriers, have been used in new fill dams since 1959, at first in construction of new dams, in covered position. The use of upstream exposed geomembranes in new fill dams started at the beginning of the 1980ies, due to greater confidence acquired the use of these relatively new synthetic materials. Since the 1980ies, design and manufacturing of geomembrane materials, and design and installation techniques of waterproofing geomembrane systems, have been constantly developing. At beginning of the new century, the technology became mature and its use has successfully spread to several dams in the world. The major assets of geomembranes in rockfill dams are their outstanding elongation properties, which allow resisting settlements, differential movements, and earthquakes that would destroy more rigid water barriers such as concrete facings, the possibility of engineering them to resist environmental aggression, their permanent availability in the needed quality and quantity (which for example does not apply to clay cores). From a construction point of view, a GFRD permits - To build the dam on highly deformable foundation - A steeper upstream face, which means less volume of fill - To build the dam in stages, which means less risk of overtopping the dam in case of flood - A shorter and smaller diversion tunnel - Avoiding difficulties and possible performance problems related to placement of multiple lines of waterstops, or to climatic conditions that can affect the imperviousness of the dam - Much faster construction - Due to small volume and lightweight of the components and of the installation equipment, easier site organisation and very low environmental impact - No need of maintenance over the years - Expected durability in the range of >100 years - No leakage, no shortcomings and sensitivities of traditional water barriers. The concept of a GFRD is that of providing at the upstream face o

Palavras-chave: Dams; Embankments ; Watertightness; PVC geomembrane; Geocomposite; Drainage