Functions

EPB TBM is suitable for soft soil strata and mixed ground. It conditions the excavated muck into a paste, which serves as a flexible plastic supporting medium. This balances the earth pressure at the tunnel face, prevents uncontrolled soil ingress into the machine, and enables efficient tunneling with minimal ground settlement.

The screw conveyor transfers muck from the bottom of the excavation chamber to the belt conveyor. By coordinating the screw conveyor speed with the advance rate of the EPB TBM, the supporting pressure of the conditioned pasty muck can be precisely controlled. The pressure balance inside the excavation chamber is continuously monitored by earth pressure sensors. Therefore, even under constantly changing geological conditions, the EPB TBM operator can fine‑tune all tunneling parameters to achieve a high advance rate while minimizing the risk of ground heave and settlement.

Soil conditioning extends the applicable range of EPB TBM. It mainly injects conditioning agents such as water, bentonite and foam to modify the viscosity, texture and permeability of the ground.
In this way, EPB TBM can achieve an high tunnelling efficiency even in heterogeneous soil composed of gravel, sand and groundwater, as well as under unstable geological conditions.