Study on the Waves in Coastal Zone at China-Maldives Friendship Bridge and the Protection Plan for Approach Bridge in Hulhumale

Maldives is an archipelagic country located in the Indian Ocean. Male, where its capital is located, is an island in the southeast of the North Male Atoll and faces Hulhumale, the location of the Velana International Airport, to the east across the Gaadhoo Koa Strait. In 2018, the China-Maldives Friendship Bridge was built on the Gaadhoo Koa Strait, which was the first cross-sea bridge in Maldives, successfully connecting the capital and airport. Male and Hulhumale directly face the Indian Ocean to the southeast, thus are subject to strong swells. Such special geographical conditions place strict restrains on the height and position of the bridge, as the bridge-island connection section is within the surf zone. This paper, by using numerical simulation and physical model experiments, investigated the wave propagation along the Gaadhoo Koa Strait and the characteristics of their deformation and breaking in the shallow water areas of the reef flats on both sides. The results show that under the impact of deformation and wave refraction in shallow water, the maximum ratio of the maximum wave height on the reef flats to the wave height in the open sea reaches 2.0, showing strong wave action in the breaking area. To address this issue, a breakwater was developed to protect the approach bridge in Hulhumale, and a physical model test was conducted for the purpose of verification, the result of which showed that both the force on the bridge and overtopping were reduced. After the implementation of the project, the breakwater successfully adapted to the wave action of the breaking zone and solved the problem of the impact of breaking wave splashes on the bridge. The relevant achievements can provide reference for similar projects.