2023 – Application of Rock Scour Model to Unlined Dissipaters Downstream of Dams and Hydropower Outlets: Real-life Case Studies

Shayan Maleki, Virgilio Fiorotto

Effects of climate change have increased the estimated magnitude of the design flood in many large dams. This has increased the risk of dam failure due to scouring within dissipaters. This paper presents a number of case studies covering the application of a new physically-based scour model (SM) that is able to evaluate the rock scour development, shape, ultimate depth and probability of occurrence. The model couples the hydraulics and geological aspects of scour phenomena and takes into account two main scour mechanisms: i) the maximum rock crack extension that depends on the geology, rock characteristics/mechanics and hydraulic fracturing analysis; and ii) the isolated rock block stability that depends on the flow hydraulics and rock block dimensions. The literature information related to the important role of rock crack propagation in rock scour analysis is limited, which is discussed in this paper. This novel stochastic crack propagation model is compatible with the stochastic nature of the turbulent bottom pressure field forcing the crack extension. The significance of this rock scour model is evidenced by varying the geological characteristics of the rock matrix, rock mechanical properties (e.g. rock toughness, rock matrix fracture network, fracture thickness) as well as the flood duration. SM is a probabilistic scour model, which makes it suitable for the risk-based design of new dam dissipaters, as well as risk assessment and design of rehabilitation work for the existing dissipaters downstream of dams and hydropower outlets. This is considering the importance of risk-based design in modern dam engineering. This conference paper focuses on the application of the SM to real-life dams and provides practitioners with a step-by-step guide to use the model for the risk-based design of hydraulic structures.

Buy this resource