The additional duration of riprap settlement refers to the duration difference between the riprap settling at the actual variable velocity and at the uniform velocity in the steady state,which has not been thoroughly studied yet.The theoretical equations of the settling velocity and stroke of riprap are deduced and simplified by introducing some parameters,such as the settling shape resistance coefficient,steady settlement duration of single particle and ratio of particle size to water depth.The exact solutions and the equivalent approximate solutions of the total duration and the additional duration of riprap settlement are given out,the dimensionless relation formula of additional duration and the theoretical calculation formula of average settling velocity are established.The example analysis results show that the additional duration ratio of settlement increases linearly with the ratio of particle size to water depth.By assuming linear distribution of the vertical flow velocity and the drift distance equations,the dimensionless expressions of the relative drift distance with Froude number and ratio of particle size to water depth are also established.The results show that the drift distance deviations induced by ignoring the additional duration can reach 5％～50％and even exceed 100％as the ratio of particle size to water depth get to 0.01～0.05 and 0.1,respectively.
riprapsettling velocityadditional duration of settlementpre-stabilization durationdrift distance
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维普
