摘要
Dambreak-induced bed scouring may undermine the foundation of bridge piers and other structures,and that destruction can pose a serious threat.Consequently,this paper aims at exploring the mechanisms of scouring and armoring.Firstly,the incipient velocity for nonuniform sediment particles was studied,and a formula was derived based on the angle of repose of nonuniform sediment.The results showed that the mechanism of incipient motion for sand and fine gravel differed from that for coarse gravel and cobbles.Also,comparison between experimental and field data shows that the results from the proposed formula agree well with those observed for all conditions.Secondly,a birth-death,immigration-emigration Markov process was developed to describe the bed load transport rate associated with scouring and armoring.The comparison between experimental data and computed results shows that our model can predict the bed load transport rate,although there may be some limitations,the chief of which is that there are many variables in the model to be determined through experiment.This makes its application in river engineering inconvenient.
基金
supported by 973 Program (2008CB425803)
the National Natural Science Foundation of China (Grant No. 50979064)
