Implant™ Method adopted as countermeasure against subsidence around the Kando River embankment, Japan

Length of over 43m long sheet pile installed with high accuracy, and expectations for continuous adoption and sales rises

2022.5.26 NEWS RELEASE

The ImplantTM Method of GIKEN LTD. (Head Office: Kochi City, President: Shinnosuke Moribe) and the Pile Installation Quality Control System “Implant NAVITM,” a system jointly developed with group company CITEC INC. (Head Office: Tokyo, President: Masanori Mitobe), were adopted for measures against the ground subsidence around the Kando River, Izumo City, Shimane Prefecture, Japan.

The surrounding area of the Kando River suffers from ground subsidence occurring in the weight of the river embankment. The ground subsidence has occurred on both banks for about 7.5km, and more than 160 houses and sheds are tilted or cracked. This construction is part of the large-scale measures that the Japanese government commenced in FY2021, and the construction for the first year has been completed. Measures will be taken for approximately 7.8 kilometers section by FY2025, and rapid resolution is expected from the region.

The ability to install a long sheet pile that reaches the basement stratum with high accuracy was highly praised. GIKEN anticipates continuous adoption of the Press-in technology in the future, and expect to expand the sales and rental of the SILENT PILERTM and the Implant NAVI.

■Ground subsidence around the Kando River

Ground subsidence around the Kando River has been continuously confirmed in multiple locations since it was first confirmed in 2002. In some areas, subsidence of more than 50 cm has occurred.

In the Kando River basin, river embankment construction has been carried out since 1993 for the purpose of flood control. The soft ground layer at the site was thicker than assumed, and subsidence occurred and has been continuing for more than 20 years. In the past, countermeasures such as steel sheet pile installation and soil improvement were taken.

However, the soft ground at the site failed to support the embankment, resulting in differential subsidenceof houses. It was determined to repress the subsidence by installing a sheet pile of up to 45m in the target section.

■Details of Press-in Work

Using the SILENT PILER F301 with water jetting and the Implant NAVITM, 195 sheets of HAT sheet piles with lengths of 43 meters to 45 meters were installed to construct a continuous wall to prevent the dragging subsidence between the embankment and the residential area. The total installation distance was approximately 180 meters along the Kando River (60 meters × 3 locations).

Standard cross-sectional view

■Features of the Implant NAVI

The "Implant NAVITM" acquires data of embedded depth, displacement, and inclination of the piles being installed in real time by “360° Prism” - optical equipment installed on top of the pile and measuring equipment called “Total Station”. It is an integrated system that realizes high quality pile installation control, automatic creation of various as-built documents, and creation of 3D drawings. The utilization of the Implant NAVI is widely spreading as it improves quality control, work progress control, and reduces costs.

Photo of construction scene using the Implant NAVI

■Selection Basis

[Realization of high-precision pile installation of long piles]

A maximum of 45 meters long sheet pile had to be installed to embed the pile into the basement stratum. Unlike other pile driving machines, the Press-in machine grabs and installs the HAT sheet pile by grasping the two points on both ends of the pile. Therefore, down-stroke power can be conveyed to the sheet pile precisely, and displacement of the pile toe will not easily occur. In addition, the Implant NAVI will achieve high-precision installation of long piles. A trial construction was carried out in May 2021 during the selection of the construction method, and the high accuracy of the installation was highly evaluated.

[Vibration and Noise-free pile installation]

The construction sites are soft ground and are around residential areas. Vibrations and noise by the pile driver could induce further ground subsidence, and the impact on the surrounding residents was a concern. The advantages of the Press-in technologies - vibration and noise-free pile installation, were highly evaluated from the viewpoint of the surrounding environment.

■Project Summary

Project nameKando River Soft Ground Countermeasure Work
LocationSite at Nishizono Town, Izumo City, Shimane Prefecture
Project OwnerIzumo River Office, Chugoku Regional Development Bureau, Ministry of Ground, Infrastructure, Transport and Tourism
Specification of pile materials195 HAT sheet piles (45H type, length 43m to 45m) 65 sheets installed at 3 locations.
Press-in construction periodDecember 2021 to March 2022

■Profile of GIKEN Group
GIKEN developed the SILENT PILER, the world's first reaction-based hydraulic pile jacking machine, installing piles with no noise and vibration. GIKEN Group now actively promotes the Press-in Technology worldwide and contributes to the construction industry by proposing and implementing innovative solutions. The innovative technology of press-in provides a unique solution and the adoption of this technology has grown to more than 40 nations and regions.

Contact Information:
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