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PhD Thesis
Department of Hydraulic and
Environmental Engineering
Riprap Design for
Rockfill Dams
Priska Helene Hiller
Supervisors: Professor Leif Lia
and Professor Jochen Aberle
Background
Rehabilitation of Svartevatn dam: placement of
riprap stones on the downstram slope
Drawing of placed riprap
Downstream slopes of Norwegian rockfill dams are strengthened with a placed riprap against
accidental overtopping or considerable leakage through the dam. Stones are placed in an
interlocking pattern with their longest axis inclined towards the dam axis as shown in the
figures. The current guidelines are based on the knowledge about dumped riprap despite
the stones have to be placed in an interlocking pattern. Hence, there is need for more
understanding of the additional strength gained by placed riprap.
Objectives of the study
• Literature study of riprap design and practical solutions for steep slopes
• Identification of the hydrodynamic forces due to the flow over steep slopes and flow
through the riprap
• Execution and analysis of laboratory tests and large-scale field tests
• Identification of the relevant parameters of the riprap material as well as the effect of
placement patterns
This study is financed by Energy Norway and the Research Council of Norway. The support of
the collaborating companies in the project “PlaF” is kindly acknowledged.