Mainline Segment 9 Project
The project involved the construction of a 36-in. diameter HDPE water line inside of a 48-in. diameter casing, that ran under highway I-20 and a Union Pacific Railroad near Stanton, TX.
While using their 48SCII TBM with standard carbide cutter head, J & J Boring, Inc. encountered rock conditions midway across the bore which were not stated in the pre-bid GDR. The unanticipated ground proved challenging to mine with the initial TBM cutter head setup. After a few worn tooling changes, the contractor decided to develop a better solution to mine the rock.
- Installation in hard caliche/limestone rock
- Crossing under active rail line and I-20 Highway
- Actual project rock rating was 40% harder than pre-project GDR indicated
- Hardest rock encountered within sensitive rail road Zone A, requiring 24-hour non-stop construction and no surface access
Key benefits of owning an Akkerman TBM is the interchangeable cutter heads feature and the ability to access the face of obstruction removal. J & J Boring, Inc. contacted Akkerman for a Disc Cutter Head attachment for their 48SCII TBM to fracture the hard caliche and limestone rock into pieces while maintaining alignment despite geological variations.
The 48SCII TBM Cutter Head features:
- (16) 6.5-in. disc cutters, capable of 5 tons of thrust each
- Cutter head rock scrapers assist in transferring cuttings away from the face, to the conveyor, then to the haul unit for removal from the tunnel
- Heavy-duty bearing to handle disc thrust loads
- Recommended Uni-directional operation for effective mining
The lead 48-in. casing was welded to the TBM to counteract the rotational torque necessary to mine the rock with uni-directional cutter head. The operators monitored the thrust loads on the cutters to ensure they did not become overloaded.
- J & J Boring, Inc. completed the drive in challenging rock that would have been otherwise improbable
- No cutter head tooling replacements required
- Mid-project rock testing indicated project rock samples of 13,000 PSI UCS.