Implant™ Method Used in Pier Foundation Work for Shutoko Renewal Project

The all-at-once replacement work of bridge girders for the project to renew Daishi Expressway Bridge on the Shutoko, or Metropolitan Expressway, using pier foundations built with the Implant^TM Method of GIKEN LTD. (Head office: Kochi-shi, Kochi; President: Shinnosuke Moribe), was completed in June. Tubular sheet pile pier foundations^*1, which offer considerable supportive strength, were chosen for the foundation work, and long piles, around 50 m in length, were pressed in. This Implant^TM Method was highly regarded for its high precision and safety in pressing in, and for allowing early completion. The press-in work was carried out by GIKEN SEKO CO., LTD., a Group company (Head office: Kochi-shi; President: Akihiro Nishigawa).

Aging expressways is a national issue, and with the urgent need for major repairs and renewal work, amendments to the Road Development Special Measures Act and the act that allows tolls to be collected that were passed in May include a fifty-year extension of the period during which tolls will be collected, from its current 2065 to as late as 2115. These amended acts have allowed funding to be secured.^*2 Work will continue in the future, including on measures for the aging expressways nationwide, and on making them four lanes.

*1. The foundation structure uses tubular sheet piles pressed in deep into the ground to enclose the soil, and then concrete is poured into this space.
*2. The Ministry of Land, Infrastructure, Transport and Tourism estimates that the total cost of expressway repairs needed by 2115 will top 8.3 trillion yen.

The Shutoko was first opened in 1962, but increasing age and traffic volumes have caused damage to worsen. This is why the Shutoko Renewal Project is underway to completely replace its roads and bridges.

Daishi Expressway Bridge, which was opened in 1968, carries some 80,000 vehicles daily between Tokyo and Kanagawa, but cracks were identified in more than 1,200 locations on it. The replacement work involved constructing new piers, then sliding a new pre-assembled girder section over the existing girder section to replace it all at once. This innovative method shortened the time the bridge was closed to traffic to two weeks, drawing attention.

* Reference: Metropolitan Expressway Co., Ltd. website (https://www.shutoko.jp/ss/daishibashi/)

Tubular sheet pile pier foundations for P4-6 piers were constructed. Our GRV1230 (SP12) pile press-in and extraction machine, which can handle 1,000 mm-diameter tubular sheet piles, was used to press in a total of 192 tubular sheet piles ranging in length from 49 to 53 metres.

Press-in that allowed high precision to be maintained even for long piles
Normally, the longer the pile the more difficult it is to maintain precision, but the SILENT PILER^TM pile press-in and extraction machine we manufacture and sell grips the pile low, near ground level, to press it in, so the down-stroke power is properly transmitted to the pile, making it harder for the pile toe to change position. These advantages allowed the construction of foundations with high precision.

Safe, quick construction with no effects on traffic
To maintain traffic flows on the Daishi Expressway Bridge right next door, even during construction, it was necessary to ensure high safety levels and complete work quickly. The SILENT PILER^TM not only grips driven piles firmly but grips the new piles not at the top but near the middle, ensuring physical stability for both machine and pile without the risk of toppling over. In addition, the pressed-in piles are held strongly through hydraulic pressure, ensuring that even long piles will not wobble and come into contact with the bridge. Also, being able to carry out work through being self-moving atop driven piles means that there is no need for the large temporary bridges required by other construction methods that employ large machinery, meaning that installation and removal work are not required. The extremely high construction safety levels and simple process mean that work can be done speedily, without affecting traffic.

■Profile of GIKEN Group
GIKEN developed SILENT PILER^TM, the world’s first reaction-based hydraulic pile jacking machine, installing piles without noise or vibration. GIKEN Group now actively promotes its press-in technology worldwide and contributes to the construction industry by proposing and implementing innovative solutions. The innovative press-in technology provides a unique solution and the adoption of this technology has spread to over 40 nations and regions.