Gyropress Method™ adopted in disaster restoration work in Kuma River, Japan　

The Tubular pile Rotary cutting press-in method, Gyropress Method of GIKEN LTD.  (Head Office: Kochi City, President: Shinnosuke Moribe) was adopted in the restoration work of National Route 219 at Kumamoto prefecture, Japan, and completed the installation works.

National Route 219 is a national highway of Japan that connects Kumamoto and Miyazaki prefecture. After the torrential rain, the road retaining wall collapsed at National Route 219. The conventional method would have required the construction of a temporary pier to reconstruct the retaining wall at the site. This would take a long construction period, and shutting down the road was unavoidable. By utilizing the Gyropress Method, GIKEN has rapidly completed the construction of the Implant™ Structure that can withstand road shoulder collapse due to scouring and runoff of back sediment, while minimizing traffic impacts.

The torrential rain, called the Reiwa 2 July Heavy Rain (Kumamoto Heavy Rainfall), hit the area in July 2020. Damage caused by the Kumamoto heavy rainfall was devasting. In some areas, reconstruction works are still yet to start, and rapid reconstruction is desired as these disaster-stricken sites hinder the life of residents and industry. More than 170 locations were similarly damaged by about 100km along the Kuma River on the national and prefectural roads. In many of these sites, the superiority of the Press-in technologies can be demonstrated.

The Press-in technologies of GIKEN, which can quickly construct a robust and resilient Implant structure, have been adopted in various sites, including Fukuoka, Nagasaki, and Oita prefecture. These locations have also suffered similar damage from the Kumamoto Heavy Rainfall. We will endeavor to actively promote technical proposals to provide a reliable and robust infrastructure to the disaster-stricken sites as quickly as possible.

※The Implant Structure is a structure which pile has been installed by the Press-in machine firmly to the ground and is integrated with Earth. Each of the piles are firmly embedded to the ground, making it resilient to external forces such as earthquakes, tsunamis, and floods.

The torrential rain that occurred in July 2020 caused the overflow of the Kuma River, causing severe damage mainly in Kumamoto Prefecture. The L-type retaining wall collapsed at this site due to the heavy rainfall. The “Implant Structure” road retaining wall was constructed over 60m to withstand shoulder collapse caused by scouring and backside sediment runoff. 43 tubular piles of 1200mm in diameter were installed by two units of SILENT PILER^TM F401-G1200. Also, 42 small-diameter tubular piles with a diameter of 318.5mm were installed to connect the piles to prevent sediment from flowing out from between the tubular piles.

The construction site was located in an area where many vehicles related to disaster remediation pass, and rapid completion to minimize the impact on traffic was required. With the conventional method, large and heavy machinery would be required on-site, and shutting down the road for a long time was unavoidable. To secure the construction yard, it was also necessary to construct a temporary pier with a width of 6 to 8m on the river's bank. This was estimated to take more than four months. Compared to the conventional method, Gyropress Method uses a compact-size Press-in machine. The machine self-walks on top of the previously installed piles and eliminates the need for temporary work platforms. While ensuring one-sided alternating traffic*, two units can work simultaneously and rapidly complete the reconstruction work. The Gyropress Method was adopted as the only method capable of resolving the constraints at the site.

※ At the construction site, the traffic was temporarily shut down only during the pitching and supplying of the tubular pile to the press-in machine.

■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.