2024 – Advances in 2D/3D Fluid-Solid Numerical Coupling for Rock Scour and Dam Safety Assessments

E.F.R. Bollaert and Eric Lemont

Rock scour downstream of high-head dams and in unlined channels and stilling basins of dam spillways is becoming a frequently occurring phenomenon. Climate change and related regulatory requirements generate frequent functioning of dam spillways, and sometimes triggers a first main spillage of spillways that have been constructed decades ago but were never used, or only used for minor discharges. Hence, unlined rock masses downstream of those structures experience greater hydraulic stress by action of hydrodynamic pressures at the water-rock interface. Sound prediction of rock scour potential becomes more pertinent, especially for cases where the scour hole may potentially regress towards the dam or spillway foundations. This paper firstly presents an innovative cloud-based digital platform for rock scour at unprotected rock bottoms downstream of high-head dams and in unlined plunge pools and spillways. Second, the paper presents the application of this novel cloud-based digital platform to two different situations of rock scour at hydraulic structures. The first case concerns the 3D numerical reproduction of observed scour after a major flood event at an unlined plunge pool downstream of a ski-jump spillway of an Australian dam, while the second case proposes 3D scour potential for a fictitious dam containing a bottom outlet with downstream lining and baffle blocks, together with a crest spillway and bridge piers in the downstream bedrock of the river channel. For both cases, the latest advances in fluid-solid coupling techniques and related 2D and 3D graphical outputs are presented.