Gyropress Method™ and GRB System™ Adopted for Permanent Revetment Restoration Following theOkunoto Heavy Rain Disaster

GIKEN LTD. announces that the Gyropress Method™, which uses its GYRO PILER™ rotary cutting press-in machine for tubular piles, and its GRB System™, which enables construction without temporary works, have been adopted for revetment restoration works on the Tsukada River in Wajima-shi, Ishikawa Prefecture, following flooding caused by the 2024 Okunoto Heavy Rain Disaster. GIKEN SEKO CO., LTD., a GIKEN Group company with extensive experience and proven technical expertise in the method, is carrying out the work under challenging site conditions with the aim of completing it as quickly as possible. 

The project site presents challenging conditions, with hard ground and a confined construction environment surrounded by guesthouses, warehouses, and other facilities. The originally planned restoration method using large concrete block revetments to restore the original configuration raised concerns about the construction period and potential impacts on the surrounding environment from work such as removing the existing revetment. To address these issues, a continuous tubular pile wall structure utilising proprietary press-in technology was adopted. In addition, even after emergency restoration using large sandbags, the existing revetment remained severely damaged, making rapid permanent restoration essential. 

For this project, two GYRO PILER™ units are being operated simultaneously to accelerate construction of a resilient Implant™ Structure revetment. The two units enable direct press-in installation of tubular piles into hard ground and through the existing revetment while minimising vibration and noise, thereby creating a structure capable of withstanding external forces with exceptional resilience.

Furthermore, the GRB System™, which eliminates the need for temporary working platforms, has been deployed to facilitate efficient construction within the constrained site conditions. 

As full-scale permanent restoration projects following the 2024 Noto Peninsula Earthquake gather pace, adoption of the Gyropress Method™ is increasing rapidly across Ishikawa Prefecture. In addition to this project, the method has been highly regarded in harbour and road restoration works, and has also been utilised for revetment restoration at Wakura Onsen, a historic tourist destination in Nanao-shi, as well as road restoration on the Suzu-Anamizu Route, a prefectural road connecting Suzu-shi and Anamizu Town. The GIKEN Group will continue to pursue technological innovation, enhance construction capabilities and strengthen proposals for construction methods, aiming to create resilient infrastructure that supports the safety and security of local communities. 

The Tsukada River is a Class B river approximately 2 km long that flows through Wajima-shi, Ishikawa Prefecture, and into the Sea of Japan from Tsukada. Wajima-shi, located in the river basin, suffered extensive damage in the 2024 Noto Peninsula Earthquake, including widespread building collapses, fires and landslides occurring simultaneously. The subsequent 2024 Okunoto Heavy Rain Disaster further devastated the area, with slopes and revetments along the river channel collapsing. Large volumes of sediment and driftwood were carried downstream, causing river blockages, overtopping and flooding, and inflicting further damage across the basin. Permanent restoration works are underway on five rivers in the Okunoto region, including the Tsukada River. Because of the high risk of secondary disasters and the advanced technical expertise required, the national government is carrying out the restoration works on behalf of the prefectural government.

To restore the damaged revetments, new revetments are being constructed along an approximately 90 m section of the river (185 m in total for both banks).

Using two GYRO PILER™ F401-G1200 units and the GRB System™, a total of 185 tubular piles, each measuring 13 m in length and 800 mm in diameter, are being installed. In addition, to prevent soil leakage between the piles, 183 small diameter tubular piles with a diameter of 318.5 mm are being installed between the large-diameter piles to eliminate gaps. 

Challenges in the Original Construction Plan
The project site is characterised by hard ground conditions and a confined construction environment, with guesthouses, warehouses and other structures located in close proximity. Conventional construction methods would have required the existing block revetment to be removed in advance, raising concerns over potential impacts on the surrounding ground and nearby buildings, as well as an extended construction period. In addition, although emergency restoration had previously been carried out using large sandbags, the revetment remained severely damaged and was at risk of suffering further damage during periods of high water. As a result, rapid permanent restoration was urgently required.
Furthermore, as buildings are located immediately behind the revetment, temporary working platforms extending over the river would normally have been required to provide sufficient working space. Ensuring flood-control safety during construction was also a challenge. 

How We Addressed the Challenges
The Gyropress Method™, which installs tubular piles fitted with cutting bits at their toes by rotary press-in, enables direct construction in hard ground and in conditions where underground obstructions such as existing structures and concrete are present, while minimising vibration and noise. This eliminates the need for extensive removal of the existing revetment, thereby reducing impacts on the surrounding environment and shortening the construction period. In addition, the simultaneous operation of two GYRO PILER™ units is being employed to further improve construction efficiency and expedite project completion. Furthermore, by utilising the GRB System™, which enables the entire press-in process, including pile conveying, pitching and installation, to be carried out on top of the installed piles, large-scale temporary works over the river are no longer required. These advantages were highly valued, leading to the adoption of the method for this permanent restoration project, where both rapid recovery and long-term functionality are essential. The solution enables the rapid construction of a resilient Implant™ Structure revetment while meeting the project's demanding requirements. 

■Profile of GIKEN Group
GIKEN developed the SILENT PILER™, the world’s first reaction-based, non-vibratory hydraulic pile driving machine that operates with minimal noise impacts. The 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.

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