Experimental and Numerical Study on Scour-Protection Methods in a Stilling Basin: Case Study of Chancy-Pougny Dam
Publication: Journal of Hydraulic Engineering
Volume 147, Issue 6
Abstract
Chancy-Pougny is a run-of-river dam on the Swiss–French border constructed in the early 1920s. Since its commissioning, the operation of the four spillway gates has been responsible for a progressive erosion of the stilling basin. The future scour potential of the unlined stilling basin of the Chancy-Pougny dam was assessed by hybrid modeling, combining both a physical and a numerical model. The physical model investigated the flow structure in the basin as well as the dynamic pressure fluctuations exerted by the flow on the rocky bottom of the stilling basin. The presence of a large gyre, generated by a flow recirculation in the nonsymmetrical basin, was found to be one of the main causes of significant scour formation. The numerical model used the pressure recordings to reconstitute the observed scour since 1924, predicting significant additional long-term erosion in the stilling basin. As such, a series of scour mitigation measures, including a free-standing wall and various configurations of concrete prisms for scour protection, were tested on both models. A tailor-made solution containing a layer of randomly distributed concrete prisms laid on the basin’s current bottom was identified through this study, proving the importance of both numerical and physical approaches in hydraulic engineering.
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Data Availability Statement
Some or all data, models, or code that support the findings of this study are available from the corresponding author upon reasonable request. Specifically, the authors are available to provide data that were used to create the figures in the manuscript for both physical and numerical models.
Acknowledgments
The authors would like to acknowledge the SFMCP for commissioning the study, and all the people involved in the study: Mr. Olivier Vallotton and Mr. Etienne Dufey (Stucky SA, Switzerland), Dr. Thierry Bussard (Norbert SA, Switzerland), and Dr. Matthieu Ferrière (CNR, France). The helpful inputs of Dr. Pedro Manso [EPFL PLatforme (PL)-LCH] and the support of Ms. Mélanie Baehler are also acknowledged.
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Journal of Hydraulic Engineering
Volume 147 • Issue 6 • June 2021
Copyright
© 2021 American Society of Civil Engineers.
History
Received: Dec 10, 2019
Accepted: Nov 25, 2020
Published online: Mar 19, 2021
Published in print: Jun 1, 2021
Discussion open until: Aug 19, 2021
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