Nanchang Subway Line 2 Tunnel Project

Φ 6.28m CREG EPB TBM

Project Year: 2023

Project Summary

Route Overview:

  • The shield machine sequentially tunnels beneath clusters of buildings:

    • Fire brigade buildings,

    • 1-6 story residential buildings,

    • Nanchang Public Transportation Group Building

    • 2-7 commercial story buildings.

Construction Difficulties

Geological and Construction Challenges:

  • The tunnel section is located in a full-section water-rich sandy stratum with abundant groundwater.

  • The tunnel needs to pass under multiple buildings

  • A 320-meter small-radius curve

  • The site is limited in space, making the construction process even more challenging.

Jello-Mud Result

Injection Process:

  • Inject Jello-Mud into the soil chamber via bentonite injection system to replace soil spoil.

  • Rotate the cutter head at intervals to ensure Jello-Mud reaches the front of the cutter head.

  • During injection, monitor the changes in soil pressure within the chamber to ensure a stable soil chamber pressure is established in front of the cutter head.

  • This process helps to prevent groundwater from infiltrating into the soil chamber.

Photos taken from the TBM pressure system. Before and after Jello-Mud injection. Soil chamber pressure was at 0.26 - 0.55 bar before Jello-Mud Injection. It reached 1.66 - 1.93 bars after the soil was fully replaced by Jello-Mud.

Soil chamber was maintained at 1.52-1.84 bar even after 48 hours of downtime.