Hard-rock TBM
Single-shield TBM
The single-shield TBM is specified for complex rock with uneven strata, fracture zones and a low groundwater table, where the side walls are too weak to take the reaction loads required by an open-type gripper machine. The shield protects the work area while segmental lining is installed inside it, which makes the configuration suited to ground that cannot support a gripper TBM.
Working principle
A single-shield TBM is used in geological conditions where rock strength is weak and the side walls cannot react the loads produced by gripper shoes. During a drive, a rotating cutterhead equipped with disc cutters is pressed against the tunnel face to cut the rock, and chips fall away from the face into the muck system.
Unlike an open-type gripper machine, the single-shield TBM uses segmental lining as its primary rock-support method. Thrust cylinders push the machine forward by reacting off the most recently installed segment ring, and segment installation and excavation are carried out alternately rather than simultaneously: the machine advances one stroke, the ring is built inside the shield, and the next stroke begins.
Features
Cutterhead built with composite chromium-carbide wear-resistant plate and carbide cutter bits at the cutterhead edge for high wear resistance and long service life
Main drive on a double-row cylindrical roller thrust bearing for service life and safety
PLC control system with real-time monitoring and data acquisition
Multi-material transport system handles segments, pea gravel, consumables and other tunnel material
Cutterhead water-spray jets, dust extraction and air cooling reduce dust formation in the working environment
On-board drilling and grouting system available for ground reinforcement at unstable soft rock or fracture zones
Specifications
| Excavation diameter | 6,880 mm | |
| Length of shield + back-up | About 104 m | |
| Total power | About 2,260 kW | |
| Main drive power | 1,540 kW | |
| Maximum daily advance rate | 30 m | |
| Maximum monthly advance rate | 546 m |
Reference projects
Chongqing metro tunnel: first single-shield TBM in Chinese urban metro construction; 3.84 km section in sandy mudstone, sandstone and argillaceous siltstone; breakthrough November 2016, peak 30 m daily advance and 546 m monthly advance
- Location
- Chongqing, China
- Diameter
- 6,880 mm
- Machines
- 1
Fortezza Railway Tunnel (Verona-Fortezza link)
- Location
- Italy
- Diameter
- 9,680 mm
- Machines
- 2
- Configuration
- twin-tube double-track railway; 12.75 km bore per machine; 11th and 12th CRCHI exports to Italy
| Project | Location | Diameter | Machines | Configuration |
|---|---|---|---|---|
| Chongqing metro tunnel: first single-shield TBM in Chinese urban metro construction; 3.84 km section in sandy mudstone, sandstone and argillaceous siltstone; breakthrough November 2016, peak 30 m daily advance and 546 m monthly advance | Chongqing, China | 6,880 mm | 1 | |
| Fortezza Railway Tunnel (Verona-Fortezza link) | Italy | 9,680 mm | 2 | twin-tube double-track railway; 12.75 km bore per machine; 11th and 12th CRCHI exports to Italy |
Applications
Single-shield TBMs are specified for complex rock with uneven strata, fracture zones and low groundwater, where segmental lining is required and a gripper TBM cannot react thrust into the side walls. The configuration suits urban metro tunnelling through mixed sedimentary ground, regional water-supply work in weak rock and any drive where a closed shield is needed for safety. CRCHI's principal public reference is the Chongqing metro section, the first single-shield TBM applied to urban metro construction in China.
Configuration and engineering
Every CRCHI TBM is engineered to project. Shield diameter, cutterhead geometry, drive power, segmental ring design and back-up arrangement are configured to the alignment, ground conditions and water pressure of the drive. Project-specific scope beyond the standard envelope is engineered to brief, and where a drive calls for it, a machine is developed from the ground up. CRCHI Australia is the engineering, commercial, commissioning and aftermarket point of contact for Australian projects.
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