講題：Experiences learnt from the damage of Mataianxi Bridge
subjected to the event of 923 disastrous dam-break flood
主講人：林呈教授
中興大學土木工程學系
時間：5月19日（星期二）下午2點
地點：中央大學科學一館S-325教室
摘要：
Following the catastrophic large-scale dam-break flood that occurred in Hualien, eastern Taiwan, on September 23, 2025, the Mataianxi Bridge was severely damaged and ultimately destroyed by the event. The bridge has a total length of 452.0 m and consists of two independent girders carrying southbound and northbound traffic, respectively. The bridge failure was studied first, based on the evidences obtained from the field. It is found that the damage cause was associated with highly pronounced uprushes of sediment-laden floodwater, generated by time-dependent supercritical flows in conjunction with a series of unsteady long waves impinging simultaneously on the bridge piers. To further investigate the underlying mechanisms, a recirculating water channel and a wave flume were employed to separately examine the uprush characteristics induced by supercritical flows and long waves.
As clearly evidenced in situ on Sep. 23 and 24, the dam-break flood did consist of both supercritical flows and long waves. Therefore, the combined effect of the two uprush mechanisms should be considered in hydraulic design, particularly in determining the required bottom elevation of bridge girders under potential dam-break flood conditions.
