Jamuna – Bridge Foundations
Mr Steve Kay, Senior Engineer – Fugro Engineers BV
The Jamuna Multi-purpose Bridge, Bangladesh consists of a 5.0 km long combined road, rail and service crossing of the Jamuna [Brahmaputra] River at Sirajganj some 100 km north of the capital, Dhaka. It is the largest project ever undertaken in Bangladesh at contract value of US$ 700 million. The bridge was Bangladesh’s first major river crossing. Engineer for the project was a Joint Venture of Rendel Palmer & Tritton, NEDECO and Bangladesh Consultants Ltd. The Bridge Constructor was Hyundai Engineering & Construction Co. and the Main Contractor for the massive River Training Works a Benelux consortium of HAM/VOA.
Work commenced in 1995. The Bridge consists of seven separate six, and seven span modules of 100 m. The bridge deck is prestressed balanced cantilever units bearing on concrete piers cast on hollow precast reinforced concrete pile caps. Each pier is founded on 1:6 rake 2 and 3 tubular steel pile groups. Pile diameters are 2.5 and 3.15 m and pile penetrate to around 80 m below existing ground level. The bridge site is in a seismic area, and the piers were designed to withstand earthquakes, ship impact and massive scour. No previous attempts had been made to bridge a braided river of the strength and complexity of the Jamuna, which flows at a rate of 65,000 m3/s during the monsoon flood. The Bridge was opened for traffic in mid 1998.
The presentation included discussion on the Bridge structure, with particular emphasis on the site investigation, soil conditions, pile load tests, pile design and driving. A principal factor affecting foundation design was that the Jamuna river bed consists of approximately 70 m of loose to medium dense highly micaceous sands.
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