In July 2014, Antara Koh (I) Pte Ltd was awarded by Sumitomo Mitsui Construction Co., Ltd as the Specialist Contractor for the foundation works in the longest sea bridge in Vietnam. The Lach Huyen Bridge spans 5.44 km which connect Hai Phong City and Cat Hai Island.
Antara Koh successfully completed the installation of 174 nos x Ø1,200 mm interlocking Steel Pipe Sheet Pile (SPSP) at 3 piers on the sea and 1,040 nos x Ø1,100 mm Steel Pipe Piles (SPP) at 65 piers on the reclaimed land and 88 nos x Ø800 mm Steel Pipe Piles (SPP) at 2 abutments on the reclaimed land.
The SPSP pile length varies between 47.5 m and 45.5 m. Each SPSP piles are installed in 2 sections, lower pile and upper pile, with in-situ welding join carried out by semi-automatic GMAW welding method. The lower piles were installed with a combination of Hi-Pressure Water Jet system and Hydraulic Vibro Hammer. After in-situ welding join of the upper pile to the lower pile, the installation will be continued by combination of Hi-Pressure Water Jet system and Hydraulic Vibro Hammer, and then finalized by using Delmag D128 diesel hammer.
High precision of the positioning and verticality alignment of the SPSP was required during the installation of each SPSP due to the tight tolerance of the P-P type couplings and to achieve complete closure of the cofferdam. To manage the accuracy, guide beams were installed and 2 surveyors were deployed on-site to closely coordinate each installation.
The SPP pile length varies between 36 m and 49 m with SL coating length varies between 11 m and 36.5 m. The SPP pile is first joined by SAW welding method carried out on welding bed with rollers and motor. Pre-driving was carried out using same diameter pile equipped with Hi-Pressure Water Jet system at SPP installation location. The SPP pile will be lifted up from the welding bed and pitch at location. Installation will be started using Hydraulic Vibro Hammer and then finalized by using Delmag D100 or D128 diesel hammer. All SPP were driven to top level under ground level achieved by extension pile method.
The Slip Layer (SL) coating is a Japanese pile coating technology to reduce the Negative Friction effect to the pile bearing capacity. As the SL coating material is easy to get burn, special attention was needed during in-situ welding works. Also guides with rollers are installed during installation of the SPP pile to pre-vent damage to the SL coating.
|Aerial View of Installation of Steel Pipe Sheet Pile (SPSP) for Cofferdam|
|Semi-automatic Welding of SPSP|
|Lifting of SPSP lower segment and waterjet system checking prior to installation|
|Driving of SPSP using diesel hammer with suspension leader|
|PDA test on SPSP Test Pile using 23ton drop hammer|
|Installation of Steel Pipe Pile (SPP) with Slip Layer (SL) Coating|
|In-situ SAW Welding of SPP|
|Pre-driving at SPP location with Hi-Pressure water jet system|
|Driving of SPP using hydraulic vibro hammer|
|Installation of extension pile|
|Driving of SPP using Diesel Hammer with suspension leader|
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