[JP] Basalt Rods in Shield Tunnel Temporary Wall Cutting
Posted: 5. Oct 2025, 23:31
Toda Corporation Becomes First in Japan to Use Basalt Rods in Shield Tunnel Temporary Wall Cutting
Toda Corporation has become the first in Japan to adopt basalt fiber rods—an inorganic reinforcement material made from molten basalt rock—in shield tunnel construction. The rods were applied as reinforcement in temporary wall cutting during shaft construction for the Linear Chuo Shinkansen project, marking a significant advancement in underground construction technology.
The basalt rods boast more than twice the tensile strength of conventional steel reinforcement, while being significantly more cost-effective than carbon fiber and glass fiber alternatives. Toda utilized the material in the pneumatic caisson method for one of the deepest shafts in Japan, reaching approximately 110 meters, for the Maglev tunnel project. The shaft construction has already been completed.
What Are Basalt Rods?
Basalt rods are produced by bundling high-temperature molten basalt fibers and curing them with alkali-resistant epoxy resin. Their surfaces are specially treated with ridges to enhance bonding strength with concrete. In addition to straight rods, they can be molded into 90° and 180° hooked shapes, offering flexibility in structural design. In performance tests using shield tunneling machines, basalt rods demonstrated equal or superior cutting performance compared to carbon fiber rods.
Application and Future Use
The shaft where the basalt rods were used will serve as an emergency exit for the Linear Chuo Shinkansen once the project is completed. In temporary walls for tunnel entry and exit shafts, materials are required to offer both high compressive strength and cutting performance during shield tunneling. While carbon fiber rods meet these criteria, their high cost has been a major drawback. Toda Corporation sees basalt rods as a cost-effective, high-performance, and scalable alternative and plans to actively use them in future shield tunnel projects.
Info based on: https://www.decn.co.jp/?p=178075 Accessed 2025-10-05
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Graph: https://www.decn.co.jp/?p=178075 Accessed 2025-10-05
Toda Corporation has become the first in Japan to adopt basalt fiber rods—an inorganic reinforcement material made from molten basalt rock—in shield tunnel construction. The rods were applied as reinforcement in temporary wall cutting during shaft construction for the Linear Chuo Shinkansen project, marking a significant advancement in underground construction technology.
The basalt rods boast more than twice the tensile strength of conventional steel reinforcement, while being significantly more cost-effective than carbon fiber and glass fiber alternatives. Toda utilized the material in the pneumatic caisson method for one of the deepest shafts in Japan, reaching approximately 110 meters, for the Maglev tunnel project. The shaft construction has already been completed.
What Are Basalt Rods?
Basalt rods are produced by bundling high-temperature molten basalt fibers and curing them with alkali-resistant epoxy resin. Their surfaces are specially treated with ridges to enhance bonding strength with concrete. In addition to straight rods, they can be molded into 90° and 180° hooked shapes, offering flexibility in structural design. In performance tests using shield tunneling machines, basalt rods demonstrated equal or superior cutting performance compared to carbon fiber rods.
Application and Future Use
The shaft where the basalt rods were used will serve as an emergency exit for the Linear Chuo Shinkansen once the project is completed. In temporary walls for tunnel entry and exit shafts, materials are required to offer both high compressive strength and cutting performance during shield tunneling. While carbon fiber rods meet these criteria, their high cost has been a major drawback. Toda Corporation sees basalt rods as a cost-effective, high-performance, and scalable alternative and plans to actively use them in future shield tunnel projects.
Info based on: https://www.decn.co.jp/?p=178075 Accessed 2025-10-05
.
- 2025-10-05_decn.co.jp