Earth Pressure Balance Shield

Wherever the geology report indicates cohesive ground conditions, the EPB shield will be the first choice. The advantages: high advance rates, economical drive and comparatively little environmental damage. By means of ground conditioning with foam the range of application can be considerably enlarged.

With earth-pressure balance shields the excavated ground is used as support medium. Stabilizers such as compressed air or suspension can generally be avoíded. The force of the push cylinders is transferred via the pressure-bulkhead onto the earth slurry in the excavation chamber. Thus a balance of the earth slurry with the earth and water pressure in place can be achieved. The excavated material is removed via screw conveyor and transferred into a belt conveyor from where it can be transported to the surface either by rail transport or truck.

Basic diagram of an EPB shield:

1. Cutting wheel.
2. Drive unit.
3. Push cylinder.
4. Pressure Sensor.
5. Air lock.
6. Erector.
7. Segment.
8. Push cylinders.
9. Conveyor
10. Screw conveyor.