Thanks for posting Frank, very interesting, I live over in Torero and am working as a Geotechnical Engineer so its right up my street! haha.
These look to be reinforced concrete cast in-situ piles which will ultimately transfer the loads of everything above (structural/environmental loads etc.) into the ground via the piles. Looks like they are now digging them out down to basement level and exposing the reinforcement, as Noel said above! That will then allow them to start casting pile cap (essentially a large concrete slab) on top, tied into the reinforcement, which everything else will then be built on top of. Essentially something like this:
This foundation is the most important part of the building (but I would say that, I'm geotechnical not structural haha) and soon it wont be able to be seen or appreciated, such is the career for a geotech engineer! .
Thanks again for the updates!