Conceptual Design for Underwater Installation of Geomembrane Systems on ConcreteHydraulic Structures

摘要

Geomembrane systems have been installed successfully on the upstream face of morethan 20 concrete and masonry dams during the past 25 years. The success of these systems in controlling leakage and arresting concrete deterioration and the demonstrated durability of these materials are such that these systems are considered competitive with other repair alternatives. With a few exceptions, geomembrane installations to date have been accomplished in a dry environment by dewatering the structure on which the geomembrane is to be installed. Dewatering, however, can be extremely expensive and in many cases may not be possible because of project constraints. Development of conceptual designs for underwater installation of a geomembrane system to minimize or eliminate water intrusion and leakage through cracked or deteriorated concrete and defective joints in concrete hydraulic structures is described herein. The drained geomembrane system designed for underwater installation on the upstream face of a dam consists of a HDPE geonet drainage layer and a PVC geomembrane backed with geotextile reinforcement, anchored, and sealed around the perimeter and along vertical splices. Plans for underwater constructibility demonstration on a small-scale structure are also included. (MM).