Tunnelling works have stopped on part of the C855 section of the Circle Line extension in Singapore to investigate subsidence at the ground surface over a slurry TBM and perform extra grouting works.
The hole that opened up in the Cornwall Gardens road has since been backfilled and works are continuing to restore the local area, which saw some utility disruption to houses. The location is between the proposed stations at Farrer and Holland Village.
In the early hours of Saturday, 24 May, the road caved-in above the location of the slurry TBM to leave a 3m deep hole measuring 7m by 8m. The holed was backfilled the same day but tunnelling works at the location are at a standstill to enable inspection and further grouting works.
The 6.6m diameter TBM was on the final, northbound leg of its drives, on the section from Holland Village station to Farrer station where it will terminate, when the incident happened. The contractor on contract C855 is the joint venture of Woh Hup, Shanghai Tunnel Engineering and Alpine Mayreder (WSA).
The client, Land Transport Authority (LTA), expects that the damaged road should be re-opened by 30 May.
LTA added that it did not expect the incident to affect the overall progress of construction work on Stage 4 of the Circle Line, which is to be completed from 2009 onwards.
On the adjacent, unrelated contract C854, contractor Taisei is refurbishing two slurry TBMs at Botanic Gardens station to relaunch them on drives to Farrer station, where they will also terminate.
