ABSTRACT
The paper presents a review of several decades of spillway erosion experiences worldwide and related numerical modelling techniques developed to assess this erosion. It not only details the lessons that have been learned (or not) from these experiences, but also distinguishes the phenomena for which comprehensive numerical modelling techniques have been developed.
Spillway erosion damage may be generated by a wide range of phenomena, amongst which scour of rock bed, undermining and/or uplift of concrete slabs, abrasion and cavitation erosion of concrete, ball-milling in plunge pools, and so on. The range of situations, while being wide, have numerous features of flow and geology which are unappreciated sufficiently at the design level. Some of the phenomena may rapidly become essential to the stability of the structure. The paper discusses the most important and most frequently encountered phenomena responsible for spillway erosion damage. A brief physical background is followed by the main reasons for erosion, and the related flow and geometrical characteristics.
Also, advanced modelling techniques for scour prediction are briefly discussed, together with the damage phenomena and situations for which these techniques are relevant. The paper focuses on both recent numerical modelling techniques and real-life examples of spillway erosion damage. Both the reasons and the consequences of erosion formation are pointed out, together with the chosen mitigation measures (if any). Finally, the paper summarizes the main phenomena to account for during design stages of stilling basins, to avoid significant scour damage during the lifetime of the structure.
