The Széchy Lecture is the highest award of the Hungarian Geotechnical Society. Károly Széchy (1903-1972) was Professor of Foundation Engineering and Tunnelling at the Technical University of Budapest and member of the Hungarian Academy of Sciences. Giroud delivered the Széchy Lecture on February 10, 2017, in Budapest. Giroud’s Széchy Lecture is accompanied by a paper published in the proceedings of the 2017 Széchy Memorial Session.

Abstract

Four case histories (in Europe, the Middle East and North America) are used to address some important aspects of the design and performance of geomembrane-lined reservoirs excavated in soil and rock. After a brief introduction to geomembranes and related geosynthetics, a first case history presents the failure of the geomembrane liner of a reservoir located in karstic terrain. The following lessons were learned: a defective construction detail combined with an inadequate design (due in part to ignorance of the geological and geotechnical conditions) can cause a catastrophic failure. This case history led to the development of the double liner concept. The case history of the first double liner with two geomembranes is then presented. This case shows that adequate design is essential to control leakage, which makes it possible to construct a safe reservoir on a potentially unstable soil. A third case history shows that a “zero-leakage guarantee” offered by irresponsible suppliers, and believed by uninformed owners, can lead to catastrophic failure. This case history illustrates the importance of a design that addresses the potential consequences of leakage. A fourth case history, and related theoretical analyses, illustrate the important role played by the mechanical properties of the geomembrane. Geotechnical engineers who are accustomed to deal with complex materials, soils and rocks, are well prepared to understand the properties of geomembranes. The conclusion of this paper is that only a rigorous engineering approach can ensure the successful performance of geomembrane-lined reservoirs, and other liquid containment structures such as dams and canals. Examples presented at the end of the lecture show that large reservoirs, canals and dams have been successfully constructed with a geomembrane liner as the sole waterproof component.