The Herrenknecht EPB Shield (Earth Pressure Balance Shield) represents the leading tunnelling technology for soft and cohesive ground conditions. Designed to ensure stability, safety, and high performance, it offers precise control of face pressure and optimized excavation efficiency in soils such as clay, silt, and loam — even with variable moisture or limited permeability.
With diameters ranging from 1.7 to 16 meters, EPB Shields are suitable for both urban infrastructure and large-scale tunnelling projects worldwide.
Key Technical Capabilities
- Geology: Soft, cohesive, and low-permeability soils (clay, silt, loam)
- Diameter Range: 1.7 m – 16 m
- Support Type: Earth pressure balance (no external medium required)
- Applications: Metro tunnels, sewage tunnels, utility lines, and urban crossings
Main Advantages
- Maintains continuous face stability in soft ground through earth pressure balance
- High advance rates achievable even in cohesive soils with high clay/silt content
- No need for slurry or compressed air support
- Adaptable to mixed or variable soil conditions via soil conditioning
- Compatible with automation and digital control systems via Herrenknecht.CONNECTED
How It Works
The EPB Shield utilizes the excavated soil itself as a supporting medium. The rotating cutterhead loosens and conditions the ground, while a screw conveyor regulates the pressure balance and removes the muck.
- Excavation: The cutting wheel removes material from the tunnel face.
- Face Support: Conditioned soil stabilizes the tunnel face, preventing collapse or surface settlement.
- Material Transport: The screw conveyor moves excavated material to a belt conveyor for removal.
- Control System: Pressure sensors and automation ensure equilibrium between face and ground pressure at all times.
This integrated system allows tunnelling to proceed safely and efficiently, even under challenging geological or hydrostatic conditions.
Advanced Features
?? Adaptive Tailskin Sealing System
Herrenknecht’s adaptive tailskin sealing monitors and adjusts sealing compound usage automatically.
- Real-time monitoring of consumption and pressure
- Up to 30% reduction in sealant use
- Increased tailskin lifespan and safety
- Optional manual override for project-specific adjustments
?? Soil Conditioning Flexibility
By injecting agents like foam, bentonite, or water, the consistency and permeability of the soil are improved. This enables efficient tunnelling through mixed ground containing gravel or sand and supports steady advance rates.
?? Automation and Monitoring
Through Herrenknecht.CONNECTED, operators have access to:
- Real-time performance data
- Predictive maintenance tools
- Adaptive control for variable geologies
Operational Modes
- Closed EPB Mode: For soft, cohesive, or water-bearing soils
- Open Mode: For stable ground where face pressure support is not required
Optional slurryfier boxes and slurry pumps can be integrated for handling permeable or water-rich soils.
Global Applications
Herrenknecht EPB Shields have successfully completed over 500 tunnelling projects worldwide, including:
- Crossrail (London, UK)
- Doha Metro (Qatar)
- Grand Paris Express (France)
Each project demonstrates the machine’s adaptability, precision, and long-term reliability under diverse geological conditions.
Summary
The EPB Shield Tunnel Boring Machine offers a perfect blend of mechanical performance, safety, and adaptability. Whether used for metros, pipelines, or underground infrastructure, it ensures stable excavation and smooth operation — setting new standards in urban tunnelling efficiency.