Technical Information

High-density slurry type pipe jacking method SS mole method

Can be used for all types of pipe jacking with low thrust for long distances and sharp curves.


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.

Characteristics of SS mole method

  • Characteristic 1By filling and pressurizing the tail void with high-density slurry, the friction resistance value on the outer peripheral surface of the pipe is reduced, and long-distance pipe jacking is realized.
  • Characteristic 2Since the pressure balance due to high-density slurry is good, the effect on the ground is extremely low compared to other pipe jacking methods. It can handle a wide range of soil type from soft ground to boulder layers.
  • Characteristic 3The discharge method utilizes the pressure difference and the fluidity of high- density slurry from the face to the inside of the machine, and the mud is transported from the inside of the machine to the outside of pipe by a vacuum suction unit.
  • Characteristic 4The standard machine can take in whole boulders and handle up to 1/3 of the pipe diameter. The boulder compatible type can handle up to 100% of the pipe diameter.
  • Characteristic 5Super sharp curve pipe jacking of about 15R is possible.
  • Characteristic 6Long-distance pipe jacking of about 500 m per span is possible only by main hydraulic jack.
  • Characteristic 7Since the pipe jacking equipment is compact, it can be installed in a narrow temporary yard.
  • Characteristic 8No auxiliary construction method is required except for launching and arriving.
  • Characteristic 9Systematization from excavation to solidification processing.
  • Characteristic 10High economic efficiency.
  • Characteristic 11Small shaft construction is possible with retrievable in segments type SS mole.