Saturday, 28 June 2014

Stage 3 breakthroughs

Over the past month or so, several breakthroughs have been taking place along the Downtown Line stage 3, with the latest being at Geylang Bahru station. Under Contract 933, contractor Penta-Ocean Construction is building 4 tunnels out of the Bendemeer station. TBM3, named Bendemeer, which is manufactured by Herrenknecht as machine S-740 bore the Bukit Panjang-bound tunnel towards Geylang Bahru station. The tunnel enters a stacked configuration shortly after leaving the Bendemeer station with an escape shaft being constructed near the Whampoa River. Launched in February 2013, the machine finally docked at Geylang Bahru station.
DTL3 Tunnel Chart for June 2014

A brace was placed against the diaphragm wall within the station to limit the amount of movement caused during the breakthrough.

Works are currently underway to dissemble the TBM - this involves cutting away the cutterhead and removing all the systems from within the shield. As for the shields themselves, they will be abandoned in-situ (left in place). The next time you ride the Downtown Line into or out of Geylang Bahru station, you'd be travelling through an abandoned shield skin as all TBMs entering this station are dismantled in the same manner.

As mentioned earlier, Contract 933 is not the only contract to witness a breakthrough. Contract 930 which was awarded to SKEC also saw its machine, named Gaia, breakthrough at MacPherson station. This TBM was an Earth Pressure Balance Machine (EPBM) manufactured by Kawasaki and bore the Bukit Panjang-bound tunnel as well. As with the TBMs at Geylang Bahru, this TBM shield skin will be abandoned in-situ as well.

Photo credits - Panuwat Fongon, Kazi Shihab Uddin

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