Construction of immersed tunnel in off-shore wave conditions Busan-Geoje project South Korea

摘要

The Busan-Geoje Fixed Link Project is a major project in South Korea. The project includes two cable-stay bridges of 1650 and 1865 m and a 3380 m long immersed tunnel with a deep point 52 m (foundation level) below mean sea level. The immersed tunnel is planned to be built in deep water and in off-shore conditions. These harsh conditions for an immersed tunnel have never been seen before. The foundation conditions for the immersed tunnel are extremely difficult with very soft marine clays whose stiffness had to be improved before direct foundation on a gravel bed could be implemented. The immersed tunnel consists of 16 ordinary tunnel elements and 2 special tunnel elements with a climbing lane, all with a length of 180 m. Each tunnel element is built up of 8 segments with a length of 22.5 m where the first and the last segments are special segments with end frames and provision for bulkheads. The typical cross-section dimensions are 26.46 m wide by 9.97 m high.