Development of Flexible Structural Precast Concrete Conduits for Earth Dams

Abstract

Conventional precast concrete conduits for earth dams are fixed with prestressed concrete (PC) steel or bolts at the joints. This leads to problems of ground-following performance and water leakage, which severely hinders the performance of these installations and the wider infrastructure of which they form a part. In this study, a new type of precast concrete conduit without PC steel or bolts is developed. The following three issues are considered in the development of the new conduits: (1) the likelihood of not only bending but also lateral misalignment at the joints between conduits; (2) the likelihood of joint separation during earthquakes, especially when the conduit is subjected to axial shaking; and (3) the likelihood of leakage under bent and elongated conditions. Each issue is verified through settlement experiments, a shaking-table test, and watertightness tests. Two types of countermeasure are proposed to suppress lateral misalignment, and new precast concrete conduits with a flexible joint structure and higher watertightness than conventional ones are developed.