Geomembrane as an Upstream Impermeable Blanket of Embankment Dams - Laboratory and Numerical Study

Abstract

The use of geosynthetics has been a common practice in geotechnical engineering when the improvement of local soil characteristics is necessary. This paper presents an experimental and numerical study of the performance of HDPE geomembrane as impermeable blanket installed upstream of embankment dams, a treatment technique for very permeable foundation. Data based on project, field and laboratory tests of the Brazilian Salto Hydroelectric Power Plant were presented to gather information about the constructive method and to support further studies. A small-scale seepage model was constructed to represent the transverse section geometry of a hypothetical embankment dam, whose geometry was adopted based on Salto Hydroelectric Power Plant. Likewise, a numerical model was elaborated referring to the small-scale seepage model to perform several parametric analyses. The obtained results indicated that the geomembrane sealing system acts increasing the flow path through the dam foundation, resulting in lower pore-pressures into the dam. Additionally, the hydraulic parameters in the soil mass may vary considerably in case of damage to the geomembrane. In general, the study has shown that the use of synthetic membranes can be a good solution for treatment of pervious foundations and possible defects can lead to the reduction of their performance.