An Experimental Study Of Runup Of Successive Solitary Waves On A Gentle Slope

The run-up of single solitary wave on the slope belongs to one of the classic subjects in water wave dynamics.It has been studied for several decades in fundamental science and engineering since the middle of the last century.The run-up and breaking process of single solitary wave has been extensively studied,and the empirical formula of non-breaking solitary wave and breaking solitary wave has been proposed.Tsunami can gradually steepen and develop into a train of solitary waves or undular bores when propagating from deep to offshore shallow region.What's more,related numerical simulation research shows that the propagation and deformation of tsunami in the continental shelves in East China Sea and Sourth China See result in undular bores and a train of solitary waves in shallow water.It is important to study the run-up of successive solitary waves,which is useful to understand tsunami run-up on beeachs.However,there are few works about run-up on a slope of successive solitary waves.A well designed experiment is carried out to study the runup characteristics and breaking process of several successive solitary waves on a gentle plane beach of 1:20 slope.The modified Going method and the third order solution of a solitary wave are adopted to generate the waves in a wave flume,which includs double and triple solitary waves with identical amplitude and double solitary waves with defferent amplitude.The time series of the surface elevation are measured by nine wave gauges installed along the wave flume,the movement of the waterline on the beach and the breaking process are recorded by two high speed cameras.Based on the experimental data,the relative wave amplitude of the target solitary waves,the dimensionless distance between two successive wave crests on the runup amplifications of individual waves are discussed for the cases of the double and triple solitary waves with identical amplitude.The effects of wave superposition and breaking process to the double solitary waves with defferent amplitude are analyzed.It is found that,for the runup of the double and triple solitary waves with identical amplitude,the runup amplification of the first wave is identical with that of the single solitary wave of the same relative amplitude.The runup amplification coefficient of the leading one is greater than that of the second wave and third wave.As the relative peak distance increases,the runup amplification coefficient of the third wave and the second wave decrease at the range of the small relative peak diatance,reaches a minimum value,and then increase gradutely.For cases with great peak distance,the runup of the third solitary wave becomes greater than that of the second one.Finally,empirical formula are proposed to evaluate the runup of individual wave for the triple solitary waves and the gentle slope.As regards the double solitary waves of different amplitude,the maxmum runup amplification coefficient increase at a critical value of the relative peak distance.The effect of the ratio of amplitude of the double solitary waves on the maximum runup amplification is provided and discussed.