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Evolution of Scour Depth at Circular Bridge Piers |
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| Authors: | Wen-Yi Chang Jihn-Sung Lai Chin-Lien Yen |
| Affiliation: | 1Associate Researcher, National Center for High-Performance Computing, No. 7 R&D 6th Rd., Science-Based Industrial Park, Hsinchu, Taiwan; formerly, PhD Student, Dept. of Civil Engineering, National Taiwan Univ., Taipei 106, Taiwan. 2Assistant Research Fellow, Hydrotech Research Institute, National Taiwan Univ., 158 Chow Shan Rd., Taipei 106, Taiwan. 3Professor Emeritus, Senior Research Fellow, Dept. of Civil Engineering, Hydrotech Research Institute, National Taiwan Univ., 158 Chow Shan Rd., Taipei 106, Taiwan. |
| Abstract: | Experiments of bridge pier scour are carried out under steady and unsteady clear-water scour conditions with uniform and nonuniform sediments. Around the pier nose, the sediment size variation of surface bed materials is investigated, and a regressed formula is obtained for estimating the mixing layer thickness in terms of median sediment size and geometric standard deviation of grain size distribution. A method based on the mixing layer concept is developed for calculating the equilibrium scour depth in nonuniform sediment. Based on the experimental data of scour rate, a model simulating the scour-depth evolution under steady flow in nonuniform sediment is presented. By analyzing experimental data, a scheme is proposed for computing the scour-depth evolution under unsteady flow. |
| Keywords: | Scour Bridges piers Sediment Unsteady flow |