Pipe Jacking
Pipe Roofing Machine
The CRCHI pipe roofing machine is purpose-built for trenchless pre-support of tunnels driven beneath existing highways, railways and surface structures. Steel tubes are jacked from a launching shaft to a reception shaft and locked together to form a continuous arch above the future tunnel envelope; under the protection of that pipe roof, conventional excavation can then proceed safely. The product is a pre-support tool for the tunnelling sequence, distinct from utility pipe-jacking machines that lay service pipes as the finished asset.
Working principle
Steel tubes are jacked into the soils between the launching shaft and the reception shaft by a pipe jacking machine. Each tube is connected to the next by lock mouths to form a continuous tube arch, and water-proofing additives are injected into the gap between the tube and the surrounding soil to keep groundwater out of the tunnel envelope. Once the steel-tube arch is complete, the pre-support is in place; the tunnel below is then excavated under the protection of the pipe roof.
The machine itself uses the slurry-balance method for spoil discharge, with flow meters and pressure sensors on the slurry circuit for precise face-pressure control and reduced surface settlement. An automatic measurement system tracks machine posture in real time, and an articulation device handles deviation correction and direction adjustment in the confined launch geometry. The cutterhead is designed as a composite head capable of cutting artificial fill, mudstone, sandstone and other complicated geologies. The machine can also be retracted from the bore, which lets crews clear obstacles without a reception shaft and lets a single machine work multiple drives.
Features
Composite cutterhead handles artificial fill, mudstone, sandstone and other mixed-face geologies
Machine can be retracted from the bore, allowing reuse on multiple drives and giving crews a way to clear obstacles without a reception shaft
Slurry balance method for spoil discharge, with flow meters and pressure sensors on the slurry circuit for precise face-pressure control and reduced ground settlement
Automatic measurement system providing live feedback on machine posture
Articulation device for precise deviation correction and direction adjustment in confined alignments
Specifications
| Machine type | Pipe roofing machine with slurry support | |
| Excavation diameter | 720 mm | |
| Length (shield + back-up) | 12 m | |
| Machine weight | 63 t | |
| Installed power | 93 kW | |
| Nominal cutterhead torque | 25 kN·m | |
| Maximum thrust | 4,000 kN | |
| Average daily advance rate | 15 m/day | |
| Maximum daily advance rate | 18 m/day | |
| Geology range (reference case) | Artificial fill, clay, mudstone, sandstone |
Reference projects
Chongqing Railway East Loop Project
- Location
- Chongqing, China
- Diameter
- 720 mm
- Machines
- 3
- Configuration
- Pipe roofing machine with slurry support; geology: artificial fill, clay, mudstone, sandstone; average daily advance 15 m, peak 18 m
Sanya River Estuary Passage
- Location
- Sanya, Hainan, China
- Machines
- 1
- Configuration
- world-first triple-circular pipe-roofing machine (Lucheng); 125.8 m subsea advance, accuracy within 10 mm
| Project | Location | Diameter | Machines | Configuration |
|---|---|---|---|---|
| Chongqing Railway East Loop Project | Chongqing, China | 720 mm | 3 | Pipe roofing machine with slurry support; geology: artificial fill, clay, mudstone, sandstone; average daily advance 15 m, peak 18 m |
| Sanya River Estuary Passage | Sanya, Hainan, China | 1 | world-first triple-circular pipe-roofing machine (Lucheng); 125.8 m subsea advance, accuracy within 10 mm |
Applications
Pipe roofing is specified where a tunnel must be driven beneath a critical surface asset that cannot tolerate ground movement, most commonly an in-service highway, rail line or building footprint, and where conventional cut-and-cover or open shoring is ruled out. The pipe roof is installed first, from a launching shaft to a reception shaft, and the resulting steel-tube arch carries the ground loads while the tunnel below is excavated under its protection. The technique transfers directly to AU procurement scenarios where a tunnel or station box passes beneath an operational highway or rail line and surface settlement cannot be tolerated. CRCHI's published reference is the Chongqing Railway East Loop Project, where three machines drove the roof tubes through a mixed face of artificial fill, clay, mudstone and sandstone. Each machine is configured to the geology and pipe diameter of the project.
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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