Research On Scour At The Bridge Crossing Downstream Of Reservoir

Since the utilization of the Three Gorges Reservoir from June,2003,the clearer water and the finer suspended load has occured at downstream river below the reservoir,which could cause scouring and undercut to the downstream riverbed. Meanwhile,it could also intensify the scour of the bridge crossing,and even have a bad influence on the stability of its foundation.Therefore,it's of vital importance for the normal operation of the bridge to do research on the scour tendency of the riverbed near the bridge under the present hydrological condition.Based on the reach near the Zhicheng Bridge downstream the Three Gorges Reservoir,this dissertation firstly analyzed the phenomena of riverbed erosion in a long distance,the sediment concentration variation,and the river bed armoring,etc.Then the local scour of the No.6～No.8 pier of Zhicheng Yangtze Bridge had been analyzed concretely according to the actual field investigations provided by the Yangtze River Hydro-Conservancy Committee Chingjiang Hydrology Water Resources Survey Bureau. The analysis results revealed that the local scour around the piers developed in recent years.The tendency of the local scour still needed to do further researches.Next,the actual observation data of the reach for analysis were generalized to apply to the computation for the water stage and riverbed elevation based on the one-dimensional water sediment numerical model.Finally,the calculation results were compared and validated with the field data which indicated that the water-level computed by the numerical model was basically satisfying,and the errors occurred in the results were also explained.The calculation of the riverbed need to be done in detail later.