Singapore T219
T219 was one of the 8 contracts of the Singapore MRT Thomson Line development.
The tunnelling part of the contract was split into two distinct sections
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6.66m HK slurry machine boring 2 No 900m tunnel with in-tunnel recovery and relaunch. A 12m long NATM tunnel enlargement was required for the second drive.
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Steel pipe roof consisting of 25 No, 50m long 1m dia interlocking steel pipes using a retractable HK AVN, a first in Singapore
The main tunnel drives had to pass through some very soft ground with only 1D of cover to the surface, this was resolved by using High Density Slurry developed by MM Tunnelling, the first time in Singapore.
The pipe roof was excavated and steel frames erected on 2m centers, shotcrete was used to close the profile below the pipe roof.
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