2005 Yoshino River basin agricultural land disaster prevention project eastern trunk canal (Imagire River siphon) construction

Construction details Slurry type pipe jacking method
Method Slurry type Mud max method
Completion date May. 2007
Location of Construction Ojin-cho, Tokushima city, Tokushima Prefecture~Kitajima-cho, Itano-gun
Ordering party Shikoku Agricultural Administration Bureau
Pipe diameter φ2400㎜
Distance L=367.0m
Type of soil Cobblestone mixed gravel
Gravel size

Work summary

Nominal diameter
Distance of pipe jacking
Type of soil
N value
Percentage of gravel
Maximum gravel size
Groundwater level
Underground obstacles
Construction period

Overburden 15m & within 367m of pipe jacking length, about 200m is the construction of the Yoshino River tributary (Imakiri River) river crossing. There was a high possibility that boulders & driftwood will appear, & the construction was carried out using a Slurry type & Mud pressure balanced type compound TBM that also supports boulders. The groundwater pressure was high, & it took time for initial driving & recovery of the TBM due to flooding at the time of launching & reaching.