Local scour around submerged spur dikes under ice-covered conditions: experimental and numerical investigation

Local scour around submerged hydraulic structures under ice-covered conditions poses challenges to infrastructure stability and sediment management in cold-region waterways. This study investigates how the geometry of submerged spur dikes and the presence of ice cover influence local scour. Through flume experiments and numerical simulations, we analyze channel bed deformation and flow patterns around submerged spur dikes with varying slopes (both frontal and rear) in open and ice-covered flow conditions. The study analyzes how smooth and rough ice covers affect the scour profile, flow velocity fields, and turbulent kinetic energy (TKE) around the dikes. The results demonstrate that rough ice cover increases flow turbulence and local scour depth, with vertical wall dikes showing a greater maximum scour depth under rough ice-covered flow conditions. Notably, trapezoidal spur dikes, particularly those with a 30° slope, reduce maximum scour depths by dispersing turbulence over a broader area and minimizing near-bed shear stress, as evidenced by the reduction in peak turbulent kinetic energy (TKE) compared to vertical wall dikes. Numerical simulations closely replicate these dynamics and uniquely identify the absence of secondary scour holes around trapezoidal dikes under rough ice cover. The developed empirical equations incorporate parameters such as ice roughness (n_i/n_b) and dike geometry, improving the accuracy of scour depth estimation compared to existing models by accounting for ice cover effects and dike profile configurations, offering enhanced tools for designing scour-resistant structures in cold-region waterways.