The investigation of local scouring of bridge group piers protected by quasi-stumps group

To mitigate the local scour erosion around parallel piers caused by water flow, a protective structure comprised of simulated quasi-stumps group placed upstream of the piers is proposed. The impact of the deployment distance (L), leaf area ratio (S), and width (W) of the simulated quasi-stumps group on the scour and deposition characteristics of the riverbed around the piers was investigated through both model experiments and numerical simulations. The results indicate a good agreement between the numerical calculations and experimental outcomes. The simulated quasi-stumps group can effectively reduce the flow velocity around the piers, mitigate the water scouring effect, and promote the deposition of suspended sediment, which is beneficial to the stability of the parallel piers. The deposition of suspended sediment and the amount of riverbed sediment scouring with protection are 3.11 times and 22% of those without protection, respectively. Increases in L, S, and W of the simulated quasi-stumps group significantly enhance the deposition of suspended sediment, but have a minor effect on riverbed sediment scour.