High- density slurry with a pressure higher than the groundwater pressure (groundwater pressure + 0.02 MPa) pumped to the face creates an osmotic flow on the ground side. Then, this osmotic flow causes the high- density slurry to clog the ground, forming a mud film that completely adheres to the soil particles on the excavated surface.
This mud film receives slurry pressure to seal groundwater, fixes soil particles, and does not generate loosening earth pressure.
The ground side is always in a pressure-receiving state, and high stability can be obtained on all surfaces of the excavation surface.