EXPERIMENTAL INVESTIGATION ON THE VARIATION CHARACTERISTICS OF WAVE FORCE ON BRIDGE GIRDER BY MASSIVE RIVER TSUNAMI WITH ICE FLOES

In cold-region estuaries a massive tsunami can cause the break-up of river-ice cover, the transport of ice floes and consequent collisions between them and riverine structures. This study conducted a series of laboratory experiments on large tsunami with ice floes to clarify the characteristics of wave force with ice floes on a bridge girder. The results showed that the presence of ice floes can cause water level rise higher due to the blockage of the bridge compared with the case without ice cover. In addition, when the ice was present, a larger wave force was generated and continued until the wave dissipated. Temporal variations in the wave force were affected by the amount of ice; a large amount of ice caused an abrupt increase in the wave force, while a small amount of ice caused the wave force to increase more slowly. The drag coefficients were increased 1.5- to 2-fold because of the ice floe, which indicates that the bearing shoes of the bridges need to be strong enough to withstand the extra pressure