Nanchang Subway Line 2 Tunnel Project

Construction site of a subway tunnel, with underground construction area visible, workers in safety vests and helmets, and red banners with Chinese characters and logos.

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.

Comparison of two digital gauges displaying data in Chinese characters with blue backgrounds and green, yellow, black, and red indicators, measuring pressure or similar parameters.

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.

Technical display screen showing data related to pressure, flow rate, and other measurements, with various numerical values and labels in English and Chinese.

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