Abstract: Damage of perimeter joint waterstops is the principal cause of leakage in the concrete face rockfill dams.For the first time the failure tests have been performed on the F-type copper waterstop and PVC waterstop undertangential displacement. The results revealed the regularity of the waterstop rupture. The computation model anddesign criteria of waterstops are presented,and the engineering measures for increasing the limit displacement of thecopper waterstop discussed.