Graham Sutherland: Laying the foundations
Graham Sutherland, our Head of Production, has been documenting our Building Redevelopment. In this extract from his latest blog, he tells us about the progress made in recent months. With demolition now complete, the team have been preparing the ground and putting in foundations, ready for construction to commence.
Preparing The Ground
With the demolished buildings removed, the leftover basement areas were scraped out, filled in with hardcore, and levelled to create a piling mat. This provides a solid, flat, level surface that the piling rig can work on top of to put the piles into the ground that will support the new structure.
|Demolition along the south side of the building complete
|Building before work started. Area in red now demolished ready for new build.
|Design for new building. New foundations to go into the areas in blue.
The area to the north-west of the building uses mini-piles; short piles that are driven into the ground. Once it is in far enough it is filled with steel rebar and concrete.
In the main areas to the West and South of the building much larger CHD piles are used. Instead of hammering these into the ground an auger is used, sort of like a giant drill bit, to screw them in, causing much less disturbance to the adjacent historic building.
|On the right a CHD pile is put into the ground, on the left a pile is filled with concrete from a huge articulated arm
Shuttering and rebar
|Steel rebar is prepared, ready to go in on top of the piles, with polycarbonate shuttering built up around it.
|Rebar and shuttering going in at the east end of the site under the new construction workshop area
Concrete starting to go in
|North-West area filled in with concrete – four bolts now covered in yellow caps
The concrete is poured with just the bolts sticking out (now protected and highlighted with yellow caps). These bolts will be used to connect the steel frame that makes up the bulk of the structure of the new building. Bolt cones are used to create a cavity around the top of each bolt to provide bit of wiggle room so there is a bit of play when it comes to aligning the pre-fabricated steel elements to the bolts later on.
Some areas of the new foundations are a couple of levels underground. To make it possible to dig down this far, massive sheet piles are used to hold back and support the ground around the excavation area. In the image below you can see articulated sheets of interlocking metal that have been rammed deep into the ground.
|Sheet piles are used to hold back earth for deeper excavation
This area will eventually form the access to the historic stage machinery under the stage, some basement storage areas, and will also house the goods/passenger lift that runs from basement to the second floor.
|Here is a ring beam that will support the bottom of the new lift shaft. The black door above is at stage level so you can see the new foundations are a good couple of storeys under the ground.
|In the this picture you can see the sheet piles have been cut down to size and staggered to step down into the deepest areas, ready for the concrete to be poured for the new foundations
With the external foundations completed, we are really starting to get a sense of the new footprint of the building. At the front of the building some steel work has already arrived and started to go up. It will be fantastic to start to see the three dimensions of the new building taking shape.
|Foundations for the new studio theatre
|(L): The first steelwork going up in the north-west area next to the rehearsal room. (R): steelwork lying ready where the new foyer will be.