Water distribution main replacement laying work (Area A) between 3 Iko, Adachi-ku and 6 Takenotsuka, Adachi-ku

Construction details High-density slurry type pipe jacking method with compatible type for underground obstruction
Method Milling mole method
Completion date Dec. 2015
Location of Construction Adachi-ku, Tokyo
Ordering party Tokyo Metropolitan Waterworks Bureau
Pipe diameter φ1000㎜
Distance L=297.3m
Type of soil Silt
Gravel size

Work summary

Nominal diameter φ1000mm
Distance of pipe jacking L=252.55m L=44.78m
Type of soil Silt
N value 0
Percentage of gravel -
Maximum gravel size -
Groundwater level GL-0.75m
Overburden 10.12m~10.26m
Underground obstacles Insurance method (Remaining earth retaining wall)
Construction period (Daytime work 8.0h) Aug. 2015~Dec. 2015 (3.5 months) Jan. 2016~feb. 2016 (2 months)

Initially, the design was an cut & cover method, but due to the local environment & many underground utilities, it was changed to High-density slurry type pipe jacking method. However, a large number of leftover earth retaining wall were discovered, & the milling mall method (insurance method) was adopted.
Since the area was close to the downtown area near the station, a soundproof house was installed & construction was done at night when crossing the track. In addition, since it was designated as a flammable gas generation danger area (B rank), a simple explosion-proof equipment was installed & constructed.
The construction was completed without hitting the leftover earth retaining wall.