Sunday, 7 June 2015

T206 Excavation

Excavation works are now in full swing across all 4 structures within the T206 project.

The integral north launch shaft, along with a section of the cut and cover tunnel have been shored and excavated down to the S2 layer. The first STEC EPB TBM for the project had just passed its factory acceptance at the end of May and will subsequently be delivered to the launch shaft. Pre-assembled gantry crane segments are also laid beside the shaft.

2 telescopic excavators deployed at the Sembawang Airbase C&C tunnel
Pre-assembled gantry crane segments (in yellow)
Launch shaft openings (From left to right: Changi Bound, RT2, RT1, Woodlands Bound)
The launch shaft will see 4 individual TBM launches, first of its kind ever carried out in Singapore
Factory acceptance of the first STEC EPBM on May 28 (Photo cr: STEC)

Escape Shaft 2
The sheet pile for the structure has been completed and likewise have commenced excavation works.

Escape Shaft 2 across the SBAB
Excavation at S1

Tunnel route from SBAB to WDS

Launch Shaft 1 & 2
Excavation of the 38m LS2 have reached down to about 35m of depth. The specialist team is now carrying out blasting and shotcrete works for the crown of the 21m adit tunnel opening, required to allow space for the TBM assembly. Once the adit has reached its required length, the remaining 2.5m depth of rock will be blasted till the formation level. The first Herrenknecht Slurry TBM arrived at the launch shaft in mid-April, and is scheduled to be lowered down in 1-2 months time. The gantry crane has been assembled at the LS2.

Rock blasting works at the 22m LS1 had just commenced this week after the team encountered granite upon excavation of the 4.5m topsoil. Repeated blastings will be carried out along the remaining 17m until the formation level is reached.

Launch shaft site
Assembled gantry crane

Launch Shaft 2
Herrenknecht TBM delivered to the launch shaft (wrapped in blue)

Assembled STP
Rock encountered at Launch Shaft 1 at 4m of depth

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