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2010 – Hong Kong-Zhuhai-Macau Bridge, China.

 

vibratory-driving-of-22m-diameter-pile-_-1The construction of the Hong Kong-Zhuhai-Macau Bridge consists of a series of bridges and tunnels that will connect Hong Kong, Macau and Zhuhai, three major cities situated in the Pearl River Delta in southern China. Given the scope of this project, it is likely to become one of the landmarks in the area. The longest bridge section will be 22.8 km long and includes three cable-stayed spans between 280 m and 460 m.

Construction formally began on December 15, 2009, and the bridge is due for completion in 2016. The 6.75 km tunnel section will allow large container vessels to pass to and from the South China Sea into and out of the Delta. The tunnel and bridges will transition on artificial islands, which are formed by two circular earth-filled cofferdams; each consisting of 60 cells (which are 22 m diameter steel pipe piles), interconnected by 11 m long wing walls constructed from sheet piles. The wall thickness of the steel piles is 12 to 14 mm and on the inside of the piles additional steel reinforcing ribs are provided for shape stability. This technology is based on the “Japanese Construction Method of Steel Driven Caisson”.

In November 2010 the companies APE, APE-Holland, APE-China and Allnamics teamed up to convince the Chinese contractor First Harbour Marine Group China that a massive multi-vibro hammer could be used to drive 49 m long, 22 m diameter steel pipe piles weighing 600 tonnes each 25 m into the bed of the South China Sea, where the soil consists of silty clay, clay and sand with SPT N-values ranging from 8 to 40. Allnamics performed the vibratory drive-ability studies, which showed the feasibility of driving these gigantic piles into bottom of the sea to the required depth. The driveability study was done using the AllWave-PDP program, which uses the Method of Characteristics to analyse the system. For the soil fatigue modelling the Beta-Method  was applied.

On May 15, 2011 the world’s largest vibratory hammer drove the world’s largest pile in 7½ minutes,  just as the driveability studies performed by Allnamics had predicted.  At the highest production rate three piles were driven in a single day and seven piles in three days, and within 7 months, on December 8, 2011, the APE “Octakong” hammer drove the last of the 120 piles to the target penetration.

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It is the Allnamics opinion that in appropriate soils driving piles using vibratory hammers can not only reduce the installation time and the costs, but moreover minimises the environmental impact during installation, especially for large structures, like artificial islands, flood barriers, windmill foundations, offshore platforms, jetties and harbour quays.

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