Research On Local Scour At Bridge Piers Under Tidal Current Action

The destruction of the bridge is mainly caused by the local scour at piers, so more attention must be paid to the study on local scour at bridge piers. a great deal of research have been made and get many achievements. However with the development of estuarine, coastal and offshore engineering the result hasn't fit for the local scour at piers over tidal waterways because of many new type of piers designed and complicated tidal current.After summarizing and consulting lots of papers and researches existing currently, the research uses flood or tidal current to control experimentation based on different dynamical conditions of Qiantang estuary. The concept "design tidal range" and "initial scour altitude" are defined and the local scour at piers under tidal bore action is simulated.Based on the data of scour depth at piers over Qiantang estuary under tidal current action, such as Hangzhou-Bay major bridge etc, the principles of local scour at bridge piers and scour processes are investigated, and effects of every kind of parameters on maximum scour depth are analyzed, an equation is guided by dimensional analysis and multidimensional linear regression to compute maximum scour depth at piers under tidal current action.The equation is more simpler and clear, and the computed result are in good agreement with experimental ones, and verified well with field data of Hangzhou-Bay major bridge and experimental data over other estuary and coast. Therefore the equation to compute maximum scour depth at piers under tidal current action is applicable and provides a reliable and convenient way to maximum scour depth in engineering.