Tunnel Construction has advanced well on all three SEM stations on the Eglinton Crosstown LRT project. The teamwork between CTSC and Dr. Sauer & Partners has deepened and the daily decision-making processes following the RESS principle have resulted in good advance rates, tackling the challenging ground conditions present along Eglinton Avenue in Midtown Toronto. One of the largest underground mined Caverns in soft ground in North America is slowly taking shape as the picture below shows. Read on for an update on the construction advance of all three station locations as of end of November 2018:
At Oakwood Station, the Cross Cut has been started from the main shaft using a double sidewall drift design under the protection of a pre-installed pipe arch. The left and right sidewall drifts have been completed and advanced to the permanent headwall location. The top heading of the centre drift has also reached the headwall, and the invert closure of the Centre Drift to complete the full Cross Cut tunnel is 15m in.
From the main shaft, the Cross Cut is being excavated also using a double sidewall drift design under the protection of a pre-installed pipe arch. The top heading and bench of both sidewall drifts have reached the final headwall location, the inverts excavation is approximately half way in. From the Secondary Shaft, the Access Adit has been fully excavated and the primary shotcrete lining installed following a double sidewall drift design.
Break out into the Platform Cavern has started under a pre-installed pipe arch, also following a double sidewall drift excavation sequence. The Top Heading and Bench of the SW sidewall drift of the platform cavern have advanced towards the West to the future Breakthrough location and stopped at a temporary headwall.
The Top Heading and Bench of the NW sidewall drift of the platform cavern have advanced towards the West to the future Breakthrough location and stopped at a temporary headwall. The SE and NE sidewall drift of the platform cavern has advanced about 60m towards the East.
The Cross Cut (CC) and the Access Adit (AA) have been completed. The Platform tunnel section between the AA and CC is completed. Last week the last parts of temporary side walls were removed.
Proof drilling was carried out to check the quality of the joints in the invert. Results were showing good concrete quality and the necessary thickness. Monitoring results during demolition of the sidewall drifts were closely watched, but all remained stable.
CTSC has started to prepare the area between the CC and AA for the waterproofing and final lining works. SEM excavation of the platform tunnel continues to the west and east from the AA and the CC respectively.