An Experimental Study On Run-up Of Tsunami Waves In Wave Flume

Tsunami is an accidental, destructive ocean disaster, generated bysubmarine earthquake, landslide, and submarine volcano eruption or otherintense submarine motions. When tsunami waves propagate to the nearshore area, wave height increases dramatically owing to the decrease ofthe water depth, with significant energy, tsunami waves run up to thecoastal area and terribly result in great destruction. Using physical modelexperiments research on the dynamics characteristics of propagation andrun-up of tsunami waves, in order to understand the effects of tsunamiwaves on coastal structures, and develop new approaches to studytsunami disaster mitigation engineering, a series of physical modelexperiments on run-up of single solitary wave, double solitary waves andN-wave was carried out in wave flume.Based on the wave-generation theory, which considers effects of theunsteady wave profile within the wave generating zone of a piston-typewavemaker, we conducted propagation and run-up experiments ofsolitary wave, double solitary waves and N-wave. In the simulation ofsolitary wave, the characteristics of solitary wave generated by twomethods, in w hich the first order and the third order solitary wavesolutions were used as the target wave profile, were obtained anddiscussed within a large range of the relative wave height of solitarywaves. The experimental results show that compared with the originalGoring method, the improved Goring method could generate more stablesolitary waves in wave flume with a piston-type wavemaker.From the run-up experiments of solitary wave, the maximum run-upand the time series of moving shoreline were obtained in a large range ofrelative wave height and slope. The physical model test approach wasvalidated after the comparison with the analytical solutions available. Tsunami waves may evolve into a wave train consisted of severalisolated solitary waves during its propagation in the offshore area. Inorder to clarify the interaction mechanism between this wave train andcoastal structures, well-designed run-up experiments of double solitarywaves were implemented in a wave flume. In these experiments, doublesolitary waves with different crest distance were generated effectively bycontrolling the piston-type wave generator. Run-up experiments of doublesolitary waves with different relative height and crest distance wereconducted in the laboratory. The propagation waveforms time series ofdouble solitary waves in the constant depth region and moving shorelineon the slope were obtained and analyzed. The experimental results showthat, with regard to double solitary waves with same height, run-upamplification coefficient of the latter wave is less than the leading onewhen the relative wave crest distance is less than a certain threshold value.Moreover, this inhibition phenomenon would be more remarkable whenthe larger wave is the leading one, the run-up amplification coefficient ofthe latter wave is significantly decreased. If two waves are distinctlyovertopped before run-up, they evolve into a transient wave with twocrests and its run-up amplification coefficient is rarely larger than that ofthe single solitary wave with the same incident wave.Finally, the propagation and run-up experiments of isosceles N-wave,including leading depression N-wave and leading elevation N-wave, werestudied experimentally. The experimental results show that the deforma-tion and dispersion effects were more remarkable in terms of the relativewave height amplification coefficient. The maximum run-up amplifica-tion coefficient of leading depression N-wave is larger than that of theleading elevation N-wave propagating on a plane beach of a moremoderate slope.