Incheon Bridge project with geotextile tubes application
The new Incheon Grand Bridge – or simply the Incheon Bridge – is 18.4km (11.4mi), six-lane toll bridge in the city of Incheon, South Korea. The project was constructed in the metropolitan city of Incheon (pop. more than 2.7 million), the major seaport city on Korea’s western coast and home to the country’s largest international airport.
With three bridge lanes in each direction, the bridge now connects Songdo City and Incheon International Airport located on Yeongjong Island. It is now Korea’s longest bridge and currently the fifth-longest cable-stayed bridge in the world.
Design and construction was undertaken by Samsung Construction Joint Venture, which consisted of seven major Korean contractors. The complete project costs totaled more than $1.4 billion.
Incheon Bridge construction was accomplished using barges in deep waters and land-based construction in shallower waters along the bridges route.
It was more cost-effective and time-efficient to use land-based construction in shallow water areas. But this decision required creation of an artificial island platform to allow the use of land-based equipment.
Reclamation dikes were constructed before fill was placed within the confines of the dikes to raise the platform to the design level. Many options for the construction of the reclamation dikes were evaluated and the solution using geotextile tubes was adopted because it was more economical and satisfied the client’s technical requirements as well as construction time constraints.
The primary 12.3km (7.6mi) center bridge section was constructed in an area of soft marine and estuarial deposits in waters of varying depth and a maximum tidal range exceeding 9m (30ft).
The geotextile tube application allowed construction of the perimeter reclamation dike within a tight construction schedule as well as difficult tidal, wave, and foundation conditions. The sand-filled geotextile tube dikes adapted to the large foundation deformations and withstood wave onslaught from the sea during the entire bridge construction period.
A geotextile tube is a close-ended fabric tube with filling ports. Sand is hydraulically pumped in through the filling ports during site installation to effectively form a partially flattened “sand sausage” that acts as a reclamation dike unit.
Reclamation dikes up to 3m (10ft) high and 60m (200ft) long were constructed within a few hours using the geotextile tube application. A total of more than 14km (8.7mi) of geotextile tubes with diameters ranging from 3-5m (10-13ft) were supplied to the Incheon Grand Bridge Project as reclamation dike units to form a 1.6km (1mi) long artificial island strip that rises about 7-9m (23-30ft) above the sloping seabed.
The artificial island had to be functinal and well-maintained during the entire construction period. This geotextile tube supply contract was valued at more than $2 million.
Geotextile tubes were used successfully as reclamation dikes to construct the artificial island strip that facilitated construction of the foundation and superstructure for the Incheon Bridge project within the construction time frame. The geotextile tube solution resulted in significant cost savings over conventional reclamation dike construction methods.
This geotextile tube project is currently the largest of its kind in Korea in terms of quantity and project value. The geotextile tube diameter of 5m (16.5ft) used in this project also represents the largest dimension currently installed in Korea.