Shanghai PVG Airport JCXSG-13 Project

Large tunnel boring machine with a red and white circular cutting head inside a spacious industrial facility.
Diagram of an airport with labeled sections including Hotels Maglev, Shaft, Flight Zone Runway, High-mast Light Tower Zone, Satellite Terminal, S1-S4 Subway Tunnels, and Overhead Pipelines.

Φ 9m CRCHI Slurry-Shield TBM

Project Year: 2024

Project Overview

Project Summary

  • Project Details:

    • Tunnel Length: 3053.142 meters (from DK58+801.754 to DK61+854.896).

    • Shafts: 1 airport working shaft and 4 access tunnels.

    • Equipment: Two 9-meter diameter CRCHI Slurry-Shield TBM

    • Tunnel Dimensions:

      • Left Line: 436.5 + 2598.3 meters.

      • Right Line: 436.3 + 2597.2 meters.

    • Tunnel Shape: "V" shaped slope with a cover depth ranging from 12.11 meters to 51.00 meters.

    • Critical Infrastructure: The shield tunnels pass beneath airport runways, the existing apron, the southern apron, and the satellite terminal.

Construction Challenges

  • Soil Condition and tunnel shape

    • Soil Conditions: Tunnelling through full-section grey silty clay interbedded with silty clay and sand layers.

    • Tunnel Shape: The tunnel has a "V"-shaped slope with cover depths ranging from 12.11 meters to 51.00 meters.

    • Sandy Soil Layer: The shield machine encounters a highly mobile sandy layer in the middle section, which is rich in pressurized water.

    • Challenge: Adjusting the tunnelling parameters to accommodate the strong fluidity of the soil and its water content.

  • Critical Infrastructure

    • Tunneling beneath:

      • Airport flight zone runways,

      • Satellite terminal,

      • High-mast light tower zone,

      • S1-S4 subway tunnels at Pudong Airport,

      • Overhead pipelines.

  • Operation Difficulties

    • Issues with excessive thrust during tunnelling, resulting in difficulty resuming operation after stoppage. In some cases, the machine could not restart even after a thrust alarm was triggered.

Jello-Mud Results

This project involves a large-diameter slurry shield tunnelling through full-section sandy strata, resulting in excessive total thrust, potentially reaching the upper limit. The solution to use Jello-Mud reduced the frictional resistance between the shield and the surrounding strata, while quickly filling the annular gaps between the shield and the soil, preventing surface settlement and stabilizing the ground.

Line graph showing thrust force (KN) on the y-axis over different rings on the x-axis. Multiple lines in red, orange, and green represent various rings with and without Jello-Mud.

TBM Thrust Force with and without Jello-Mud

Line graph titled '461st Ring Thrust Force Change' showing thrust force in kiloNewtons over time in minutes. Thrust force starts around 80,000 K N, peaks above 90,000 K N early, and then gradually decreases to about 65,000 K N over 105 minutes with some fluctuations.

TBM Thrust Force Decreased 25000kN after Jello-Mud Injection and maintained at 65000kN at 461st ring

Line graph illustrating cumulative settlement in millimeters over advance cycles in ring testing for three different metro line settlement testing points, P472, P476, and P480, with P472 showing the highest settlement and P480 the lowest.

Cumulative settlement remained under -2.0mm