The 7.22m-diameter CREC 1238 will be deployed on the CR116 contract by a consortium of Soletanche Bachy International, Bachy Soletanche Singapore, Bessac and Gammon.
The TBM is approximately 60m long, weighs 866 tons, and is the first double-shell shield CREG has exported to Singapore. The machine will be launched and relaunched up to four times so the double-shell shield will facilitate disassembly in the tunnel.
CR116 includes the construction of Ang Mo Kio interchange station and twin bored tunnels with a total length of 1.2km connecting the future Teck Ghee and Ang Mo Kio interchange Sstations.
An intermediate launch shaft for the TBMs will be built between the two stations.
The tunnel alignment has a minimum curve radius of 300m and passes through geology mainly composed of Bukit Timah granite interspersed with fracture zones. There are also sections of Kallang strata (clay) and old alluvium strata, with water pressure up to four bars.
As well as the double-shell shield, special auxiliary structures have also been designed to allow for the quick assembly and disassembly of the main drive, segment erector and back-up systems.
An integrated pipeline bracket system simplifies the assembly and disassembly of slurry pipelines in the shield. In addition, to overcome the challenges of launching the TBM in a narrow launch shaft, the pipeline extension gantry has been designed to be deployed in the launch shaft instead.
The TBM also features staircases to access the segment erector’s working platform, symmetrically distributed slurry pipelines on the back-up system, mirror function and a towing force detection function for the pipeline extension device.
