John, I thought it easier to send the photos like this as I could do a little explination to each set!
The copyright comes from my software but it should really be Soletanche Bachy! If your guy wants any of the photos then I would have to seek permission and change the copyright info !
The pipe walled tunnels were in several locations:
1. Under Beach Road : the big tunnel for the MRT (the end of the cross-over was here which is why it was wide) and then a smaller tunnel above for a future pedestrian link.
2. Under Queen Street the tunnel was smaller as the tracks were side by side.
There were several horizontal pipe walls too...
3. Under the existing Bugis Station using the existing base slab as the roof
4. In the main gallery linking the existing station with the new station below an existing station entrance so a Diaphragm Wall was not possible and similarly at the Bugis Junction side to create an entrance to the shopping centre (where the KB scaffolding collapsed)
Ground Treatment in the soft marine clays
The ground treatment for the tunnels under the roads (Beach Road and Queen Street was by Jet Grouting (which was too well specified by the Engineer, so we had to claim).
The ground improvement under the existing structures was using the Spingsol technique - these were horizontal, sub-horizontal and I think some vertical for lateral support without the hassle of JGP. In the main a fibre rebar rod was inserted into the soil mix on completion of the drilling.
SPRINGSOL
Horizontal Pipe Walls
The pipes were driven using a pneumatic hammer, from recollection in some locations we needed to auger out the soil to facilitate the driving (I think because the JGP was too highly specified!) These pipes then needed to be filled with concrete before excavation.
I'm afraid these are all a bit pell-mell but you will get the drift !
The large gallery before going under the existing Bugis Station
Beach Road Tunnel
Beach Road Tunnel
Beach Road Tunnel
Finished Tunnel under Beach Road
Upper Pedestrian Link
