Hard-rock TBM
Double shield TBM
The double-shield TBM combines an open-type gripper TBM and a single-shield TBM in one machine, switching mode without major reconfiguration as ground changes. In stable rock the machine grips the side walls and runs excavation and segment installation simultaneously, which is what makes the configuration well suited to long hard-rock drives.
Working principle
A double-shield TBM is built around three main components: a front shield carrying the cutterhead, main bearing and main drive; a telescopic shield in the middle; and a gripper shield with gripper shoes and auxiliary thrust cylinders. During a drive, a cutterhead equipped with optimally arranged disc cutters rotates against the tunnel face, breaking chips off the rock.
In stable ground, the gripper shoes extend onto the tunnel side walls and react the cutterhead thrust, so excavation and segment-ring installation run simultaneously and advance rate is at its peak. When the machine reaches a fracture zone or weak rock that cannot support the gripper reaction, the telescopic shield retracts and the front shield and gripper shield close up to act as a single shield. In that mode, auxiliary thrust cylinders push the machine forward off the most recently installed segment ring, the same way a single-shield TBM advances.
Features
Two operating modes in one machine: simultaneous excavation and segment installation in stable ground via gripper shoes; sequenced single-shield mode in fracture zones or weak rock with the telescopic shield retracted
Forward-probe drilling system collects ground information ahead of the face, supporting geological mapping
Wear-resistant cutterhead built with HARDOX plate or composite chromium-carbide wear-resistant plate, with hard-alloy cutterhead edges for long service
Main drive on a double-row cylindrical roller thrust bearing for service life and safety
Multi-material transport system handles segments, consumables and other tunnel material
Shield and system layout designed to allow in-situ assembly and disassembly of machine components
Reference projects
Kaliwa Dam water diversion tunnel
- Location
- Philippines
- Diameter
- 4,800 mm
- Machines
- 1
Middle East water diversion project
- Location
- Middle East
- Diameter
- 5,270 mm
- Machines
- 1
Lanzhou water diversion project
- Location
- Gansu, China
- Diameter
- 5,490 mm
- Machines
- 1
Southwestern China water diversion project
- Location
- Southwestern China
- Diameter
- 5,560 mm
- Machines
- 2
Gansu urban and rural water-supply tunnel project
- Location
- Gansu, China
- Diameter
- 4,030 mm
- Machines
- 2
Qingdao Metro project
- Location
- Qingdao, China
- Diameter
- 6,300 mm
- Machines
- 3
Shenzhen Metro Line 8 project
- Location
- Shenzhen, China
- Diameter
- 6,470 mm
- Machines
- 3
Upper Elahera Canal Diversion Tunnel
- Location
- Sri Lanka
- Diameter
- 7,600 mm
- Machines
- 1
- Configuration
- overseas record longest single advance (>16,000 m); dual-support segment + shotcrete mode
Zhejiang Songyang Pumped Storage Power Station gravity drainage tunnel
- Location
- Songyang, Zhejiang, China
- Machines
- 1
- Configuration
- third-generation pumped-storage TBM; 30 m turning radius; 683 m monthly record
| Project | Location | Diameter | Machines | Configuration |
|---|---|---|---|---|
| Kaliwa Dam water diversion tunnel | Philippines | 4,800 mm | 1 | |
| Middle East water diversion project | Middle East | 5,270 mm | 1 | |
| Lanzhou water diversion project | Gansu, China | 5,490 mm | 1 | |
| Southwestern China water diversion project | Southwestern China | 5,560 mm | 2 | |
| Gansu urban and rural water-supply tunnel project | Gansu, China | 4,030 mm | 2 | |
| Qingdao Metro project | Qingdao, China | 6,300 mm | 3 | |
| Shenzhen Metro Line 8 project | Shenzhen, China | 6,470 mm | 3 | |
| Upper Elahera Canal Diversion Tunnel | Sri Lanka | 7,600 mm | 1 | overseas record longest single advance (>16,000 m); dual-support segment + shotcrete mode |
| Zhejiang Songyang Pumped Storage Power Station gravity drainage tunnel | Songyang, Zhejiang, China | 1 | third-generation pumped-storage TBM; 30 m turning radius; 683 m monthly record |
Applications
Double-shield TBMs are specified where a single drive must traverse both stable hard rock and unstable rock or fracture zones, and where length encourages the productivity gain of simultaneous excavation and segment installation. CRCHI has supplied double-shield machines for water diversion tunnels, urban metro work and regional water-supply tunnels. International references include the Kaliwa Dam water diversion tunnel in the Philippines and a water diversion project in the Middle East, alongside extensive water-diversion and metro deployments across 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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