Pipe-jacking loss response in Central China: plugged in 2 hours
Slurry suddenly escaped during pipe jacking for a utility tunnel in Central China. It drained along a cover channel, surface settlement hit 30 mm and kept growing, endangering a nearby gas line.
Project overview
- Region
- Central
- Project type
- Municipal utility tunnels
- Project scale
- A utility-tunnel jacking section with 30 mm ground settlement beside a gas main
Construction challenges
The main construction challenges encountered on this project.
Challenge 1Hidden leak
The loss channel ran under the cover — its location could not be seen directly.
Challenge 2Growing settlement
Settlement reached 30 mm and kept developing, risking deformation of the nearby line.
Challenge 3No long stop
The tunnel is a regional power route — downtime ripples to users.
Solution & materials
Materials and mix ratios used step by step on this project, for reference by similar works.
| Stage | Material | Function | Ratio / dosage |
|---|---|---|---|
| Plug | Rapid-set plugging agent | Seal the leak fast | Trial-mixed per leak |
| Wall protection | PAM-S concentrated slurry | Re-film and restore | 1:200 |
| Pressure | BENT-N thick slurry | Backfill, steady pressure | 10%–12% |
| Monitor | Settlement monitoring | Track settlement & returns | Every 2 hours |
Implementation notes
Following the emergency plan, crews plugged the leak with a rapid-set agent, re-filmed the wall with 1:200 PAM-S concentrate, backfilled with thick slurry to steady pressure and intensified settlement monitoring. The leak stopped within 2 hours, settlement converged, and jacking resumed 3 days later with no secondary collapse.
Delivered results
Site photos
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