Tunnel Construction Professionals
Shield Tunneling
General Manager, Shield Tunnel Engineering Department, Civil Engineering Technology Division, Obayashi Corporation Kenta MATSUBARA
Daily improvement and expanding activity field of Shield construction methods
Features of Shield Tunnelling
Shield tunneling is one of the main tunneling methods along with mountain and open-cut tunneling. It uses a shield machine to excavate the ground with cutters and to assemble segments behind the machine to construct a tunnel. It is suitable for a variety of ground types, from soft to hard.
Its main feature is the reduction of adverse environmental impact since construction is basically conducted underground except for the vertical shaft which is used as a launching and arrival bases. Its applications include sewers, gas lines, multi-service tunnels, railroads, subways, and road tunnels.
Directions of the Technological Development
The Shield Engineering Department is developing technology in the following seven directions, with a focus on shield machines and segments.
1. Longer tunnels
2. Larger tunnels
3. Faster construction
4. More durable, high-quality tunnels
5. Tunnels with cross-sections other than circular, such as elliptical and rectangular
6. More environmentally friendly construction, such as by lower power consumption
7. Construction with fewer workers
In particular, regarding the "7. Technology of tunneling with fewer people", we are committed to the development of "Obayashi Intelligent Shield OGENTS," an automated shield tunneling system that can be applied to any shield tunneling site. It divides the tunneling work into six main fields and individual automation technologies for each field are developed, with the main system integrating these technologies.
On-site capabilities and people skills
Our organization's unique strengths in creating better tunnels lie not only in technological capabilities but also in on-site capabilities and people skills.
On-site capabilities refer to the abilities developed and exerted on site. Shield tunneling is conducted without a direct visual check of the excavation surface, so we constantly observe the thrust force of the shield machine, and the force exerted on the cutter, and always observe the soil condition. We also check the progress of the construction with the results of surveying and the condition of the segment construction. Repetition of these daily tasks develops on-site capabilities.
Tunnel construction requires collaboration among everyone involved, not only our staff but also our client, local residents, subcontractors, and many more. To complete the project safely and to everyone's satisfaction, communication with all these people is crucial. Our strength lies in a high level of people skills, and the results can be seen in our achievements.
Toward the Future
At Obayashi, employees take the initiative in collaborating with workers on site, and through these experiences, each employee improves his or her knowledge and skills.
The steady growth of young engineers is noteworthy, and I hope that they will continue to work closely with onsite construction.
I would like to provide more opportunities for young engineers, having them present their skills and knowledge to people outside the company or utilize the knowledge in new projects.
Opportunities for Shield Construction
New technologies, such as URUP method which shortened the construction period by eliminating the construction of vertical shafts and OGENTS shield automation system, enabled a wide variety of shield construction projects.
We may face challenges under more varied conditions, but we will pursue further advancement in constructing tunnels that are environmentally friendly and of better quality.
