| As an extreme natural disaster,tsunami usually causes devastating damage to coastal ports,bridges,houses and other infrastructures.Since the 20 th century,498 tsunamis happened in the world and 66 of which caused huge disasters.Especially the 1960 Chilean tsunami,the2004 Indian Ocean tsunami and the 2011 Tohoku Tsunami,which not only caused a large number of casualties but also caused the destruction of many coastal bridges.China has a high risk of tsunami attack because part of China’s coast,the whole Taiwan province and part of the South China Sea are all located in the Pacific Rim Seismic Belt.It’s worth nothing that the coastal infrastructure of “the Belt and Road Initiative” also needs to consider potential tsunami threats.In addition,bridges,as the key nodes of road traffic,also play an important role in post-disaster rescue and reconstruction.Therefore,it is very necessary to study the destruction forms and mechanism of coastal bridges under the attack of tsunami and take corresponding anti-tsunami measures.The main contents of this paper are as follows:(1)Based on the dam-break theory,physical model experiment and numerical simulation,as two different research methods,are both used to simulate the tsunami bore in this paper.The Stoker theoretical solution is also used to validate the accuracy of two research methods in the aspect of the flow field characteristics and tsunami force characteristics on the bridge structures.Validation results show that the precision of two research methods meet the requirements.(2)The destruction forms and mechanism of the bridge superstructure under the action of tsunami are studied in detail based on the tsunami force characteristics and flow field characteristics of the bridge superstructure.The results show that horizontal force is the key factor leading to the destruction of the bridge superstructure.(3)The mechanical characteristics of two anti-tsunami measures including the installation of fairing and the opening of the end diaphragm are studied in detail.Besides,the corresponding anti-tsunami ability evaluation index is proposed.The results show that the installation of HX-0.50 H fairing and the opening rate K = 3 on the end diaphragm are the best antitsunami measures to the bridge superstructure.(4)The anti-tsunami ability of piers with different cross sections is studied by the quantitative indexes of characteristics of tsunami forces on the piers and the surrounding flow field characteristics.The results show that N60-60 is the optimal anti-tsunami pier with wide adaptability. |
