Engineering geotechnical investigation for coral reef site of the cross-sea bridge between Malé and Airport Island

The Malé-Airport Island Cross-sea Bridge project is the largest island-linking project in Maldives, the country known as “the kingdom of coral reefs.” Coral reef is also a special type of rock and soil medium to support significant civil engineering projects. In the Cross-sea Bridge project, the engineering geotechnical investigation of the coral reef site was divided into two stages: the feasibility study and the construction-drawing design phase. Engineering geological survey techniques were applied, and together with field exploration methods, such as geophysical prospecting and drilling exploration, the geological conditions of the site with respect to bridge engineering demands were comprehensively evaluated. In addition, the design parameters for pile group foundations were proposed based on in-situ tests, such as standard penetration, dynamic sounding, and acoustic wave testing in borehole as well as laboratory physical and mechanical experiments and bearing-capacity tests for pile foundations using rock and soil samples drilled from the site. The investigative methods adopted in the Malé-Airport Island Cross-sea Bridge project and the results obtained will provide references for similar engineering projects in the future.