SIMULATION OF SCOURING AROUND A VERTICAL CYLINDER DUE TO TSUNAMI

* Corresponding author radianta@ugm.ac.id ABSTRACT Local scour due to tsunami is damaging especially on shallow foundation. Although relatively in a short duration, tsunami attack may scour material around buildings that led to destruction. A number of formulae on local scouring due to flood and tsunami have been available. The local scouring pattern and depth produced by tsunami may be affected by tsunami duration and tsunami surge Froude number and hence different to that resulted by flood which normally have much longer duration and lower Froude number. The research used a relatively short flume to create short duration tsunami surge that run-up on 1:20 beach slope and hit a vertical cylinder on land. Both the pattern and the depth of local scouring around the cylinder were observed and the results were compared with similar research but with different tsunami surge characteristic. It was shown that the maximum scour depth was significantly deeper than the final scour depth. When compared with other experimental study of local scour due to tsunami, the present local scour maximum depth seemed to be slightly less. This could have been caused by the relatively short duration of the present experiment. It was also found that the sidewall effect was insignificant when the ratio of cylinder diameter to the flume width was less then approximately 0.15