Pipe Jacking
Rectangular Pipe Jacking Machine
The rectangular pipe jacking machine drives a box-section shield through soft soils and shallow-cover ground to install precast box culverts in a single pass. The rectangular profile gives noticeably higher usable space than circular jacking at the same overall envelope, which is why the technique has become a common choice for municipal pedestrian underpasses and metro station entrances.
Working principle
A rectangular pipe jacking machine is built around a cutterhead array, a shield, the main drive, articulated cylinders, screw conveyors, a muck car, the thruster and a reaction frame. Six cutterheads are arranged at staggered heights across the rectangular face: small cutterheads sit above large cutterheads to limit ground disturbance, and the layout reaches up to 90 percent face coverage with a 70 percent stirring rate.
During a drive, the cutterheads rotate against the tunnel face to cut the ground. Excavated material enters the excavation chamber through openings, where it is mixed with additives and stirred to a workable texture. A screw conveyor transports muck from the chamber onto a muck car, which delivers it to the launch shaft; a crane lifts the muck car to the surface muck pit. A jacking device at the launch shaft, with optional intermediate jacking stations, pushes the shield and the specially designed box culverts through the ground.
Features
Six cutterheads arranged at staggered heights cover up to 90 percent of the rectangular face with a 70 percent stirring rate, with small cutterheads positioned above large ones to limit ground disturbance
Cutterheads carry hard alloy ripper bits and cutting knives and have cut completely weathered granite in service
Bulkhead connectors accept high-pressure water jets and quartering hammers for handling boulders and other blind-area obstructions in mixed strata
Active articulation cylinders adjust direction during the drive to hold accurate alignment
Equal-thrust twin-stage cylinders shorten the launch shaft footprint
Optional bentonite friction-reducing system and intermediate jacking stations support long-distance drives
Reference projects
Huawei underground passage
- Location
- Shenzhen, China
- Diameter
- 10,200 x 6,600 mm
- Machines
- 1
- Configuration
- Gravel cohesive soil, completely weathered granite, intensely weathered granite
Nantong Metro Line 1 underground passage
- Location
- Nantong, China
- Diameter
- 7,400 x 4,900 mm
- Machines
- 1
- Configuration
- Artificial fill, clay, silt
Guangzhou Metro Line 10 underground passage
- Location
- Guangzhou, China
- Diameter
- 7,700 x 5,100 mm
- Machines
- 2
- Configuration
- Gravel cohesive soil, completely weathered granite
Hangzhou Metro Line 3 underground passage
- Location
- Hangzhou, China
- Diameter
- 3,060 mm
- Machines
- 1
- Configuration
- Mucky clay, mucky silty clay
| Project | Location | Diameter | Machines | Configuration |
|---|---|---|---|---|
| Huawei underground passage | Shenzhen, China | 10,200 x 6,600 mm | 1 | Gravel cohesive soil, completely weathered granite, intensely weathered granite |
| Nantong Metro Line 1 underground passage | Nantong, China | 7,400 x 4,900 mm | 1 | Artificial fill, clay, silt |
| Guangzhou Metro Line 10 underground passage | Guangzhou, China | 7,700 x 5,100 mm | 2 | Gravel cohesive soil, completely weathered granite |
| Hangzhou Metro Line 3 underground passage | Hangzhou, China | 3,060 mm | 1 | Mucky clay, mucky silty clay |
Applications
Municipal underground passages, metro station entrances and pedestrian underpasses under existing roads, plazas and rail corridors, where a rectangular cross section delivers more usable space than circular jacking and trenching is unacceptable. The technique is deployed at scale across Asian metro markets; CRCHI has supplied rectangular jackers across small to large box-section sizes, transferring directly to AU procurement scenarios where a metro station entrance or pedestrian underpass must be installed beneath operational surface assets. Reference deployments cover gravel cohesive soil, completely and intensely weathered granite, artificial fill, clay, silt and mucky silty clay.
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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