Introduction
Tube-à-Manchette (TAM) grouting is a widely used ground improvement technique in tunneling and underground construction. By injecting grout through sleeve pipes at controlled intervals, TAM grouting allows engineers to control groundwater inflows, reduce soil permeability, and increase ground stability. This method is particularly useful in soft ground, fractured rock, and high groundwater conditions, where conventional excavation would otherwise be unsafe or uneconomical.
This article presents case studies highlighting the effectiveness of TAM grouting in different tunneling and underground construction projects.
1. Metro Tunnel Projects in Urban Areas
Case Study: Metro System, Europe
- Problem: Deep metro station excavations encountered loose sandy soils with high groundwater inflows.
- Solution: TAM grouting was applied around diaphragm walls and beneath the excavation base.
- Outcome:
- Controlled groundwater seepage and stabilized loose soils.
- Allowed safe excavation of multi-level underground stations.
- Reduced the need for excessive dewatering, minimizing ground settlement.
Key Lessons
- TAM grouting provides an effective groundwater cutoff for underground transit projects.
- Helps protect nearby sensitive structures from settlement.
2. Tunnel Cross-Passages in Water-Bearing Ground
Case Study: Twin-Bore Railway Tunnel, Asia
- Problem: Construction of cross-passages between twin tunnels in water-bearing silty soils posed risks of collapse and flooding.
- Solution: TAM grouting was used to pre-grout around the passage alignment, forming a water-tight block.
- Outcome:
- Cross-passages were excavated without major groundwater inflows.
- Reduced reliance on ground freezing methods, lowering project costs.
Key Lessons
- TAM grouting can serve as an alternative to ground freezing, especially in silty or sandy soils.
- Effective in ensuring safe excavation for small underground connections.
3. Shaft Excavations for Tunnel Access
Case Study: Urban TBM Launch Shaft, North America
- Problem: A tunnel boring machine (TBM) launch shaft in mixed soils and high groundwater required groundwater control to allow excavation below the water table.
- Solution: TAM grouting was applied around the shaft perimeter, creating an impermeable grout curtain.
- Outcome:
- Groundwater inflows were minimized.
- Shaft walls remained stable during deep excavation.
- Enabled safe TBM launch without extensive pumping.
Key Lessons
- TAM grouting provides seepage control for shafts and portals in underground construction.
- Reduces long-term dewatering requirements, making it more sustainable.
4. Underground Caverns in Weak Rock
Case Study: Hydroelectric Powerhouse Cavern, South America
- Problem: Weak, fractured rock with groundwater seepage threatened cavern stability.
- Solution: TAM grouting was carried out along the cavern periphery to fill fractures and reduce water ingress.
- Outcome:
- Rock mass permeability was significantly reduced.
- Cavern stability improved, preventing face collapses during excavation.
- Provided long-term durability against groundwater inflows.
Key Lessons
- TAM grouting is effective in fractured rock conditions where controlling seepage is critical.
- Supports both temporary excavation safety and long-term structural stability.
Conclusion
The reviewed case studies demonstrate that TAM grouting is a versatile and reliable ground improvement method for tunneling and underground construction. Its applications range from metro tunnels and cross-passages to TBM shafts and underground caverns, where it enhances ground stability, reduces permeability, and ensures construction safety.
