1. Increased fluidity of
excavated soil
In gravel layer, rheological foams work as ball bearings and increase
the fluidity of excavated soil.
2. Reduction of fluctuations in face pressure
The compressive character of rheological foams can reduce fluctuations
in face pressure.
3. Higher watertightness of excavated soil
The groundwater in void space between soil particles of excavated
soil is replaced by tiny foams, so the excavated soil can have higher
watertightness.
4. Effectiveness in preventing adhesion of excavated soil
In hard, cohesive bedding, adhesion of excavated soil on the shield
face plate and inside the chamber is prevented.
In hard, cohesive bedding, adhesion of excavated soil on the shield
face plate and inside the chamber is prevented.
5. Easy treatment and disposal of excavated soil
Excavated soil is restored to the original state when it was in
the ground and therefore can be treated or disposed of easily.
6. Improvement of working environment
Neither clay nor bentonite is used, so the tunnel is clean and
offers a better working environment.
7. Downsizing of equipment
Only small equipment is required for generating and injecting foams.
|
|
The Rheological Foam Shield Tunneling
Method excavates a tunnel while injecting foams into the face and
the chamber. Foams are generated with special foaming agent. Injected
tiny foams with properties similar to those of shaving cream can improve
the fluidity and the watertightness of excavated soil. Foams can also
prevent the soil from sticking inside of the chamber. This enables
smooth tunnel driving while keeping face stability. In addition, the
removed soil with foams can be defoamed and put back the state before
foam injection. Then excavated soil can be easily transported and
disposed of. Thus, the method also has economic merit.
| 【Large-section shield tunneling】 |
 |
Construction of underground section of Hanshin
Electric Highway line near Fukushima
(Diameter: 10.8m, length: 210m)
|
| 【Long-distance, small-radius-curve shield
tunneling】 |
 |
Improvement of the Higashi-kibogaoka
storm sewer
in the Midori treatment district
(Diameter: 6.15m, length: 2,050m, radius: 20m) |
|
