Foundations
The is a new apartment block going up not far from my house, and only about 150m from the rivers edge.
Because the water table is not very far below the surface, and it is likely to be just metres, the ground is really quite soft.
If you doubt it, then during rainy periods, I see moisture breaking through the bitumen street surface.
So here you see a large excavation which will be for the underground carpark. Then in come the pile drivers.
The timber poles you see here would be about 8-9m long and are treated hardwood. The treatment is done under pressure and heat (I think) and the liquid penetrates the timber to varying degrees, and protects the wood from both white ant attack and rot.
While I watched, the pile driver lifted a pole vertically, the flat end (no pointy ends) is rested on the right position on the ground, a steel cap placed on the top of the pole, and then the machine has that heavy steel weight that gets lifted and dropped constantly banging the pole into the ground.
The pole penetrates the ground by about 300mm initially, then when the top is at ground level, a circular sleeve is placed on top with a knife action mid-bar, and another pole then lifted into place, and on the first bang the poles butt together with the joiner.
As the depth increases, the amount of penetration reduces.
This single foundation point took 3 and half poles before the bottom of the first was making the ground under my feet rumble a bit, meaning solid ground. So it would have been roughly 28m or about 90 feet down to solid ground.
This foundation would take hundreds of foundation points multiplied by 3-4 poles each and weeks to complete.
Then the poles are resting on solid ground and cut off low, and the concrete basement is laid resting on all the pole tops, so that (hopefully) the building doesn't sink.
See the ACTION up close.
Foundations
The is a new apartment block going up not far from my house, and only about 150m from the rivers edge.
Because the water table is not very far below the surface, and it is likely to be just metres, the ground is really quite soft.
If you doubt it, then during rainy periods, I see moisture breaking through the bitumen street surface.
So here you see a large excavation which will be for the underground carpark. Then in come the pile drivers.
The timber poles you see here would be about 8-9m long and are treated hardwood. The treatment is done under pressure and heat (I think) and the liquid penetrates the timber to varying degrees, and protects the wood from both white ant attack and rot.
While I watched, the pile driver lifted a pole vertically, the flat end (no pointy ends) is rested on the right position on the ground, a steel cap placed on the top of the pole, and then the machine has that heavy steel weight that gets lifted and dropped constantly banging the pole into the ground.
The pole penetrates the ground by about 300mm initially, then when the top is at ground level, a circular sleeve is placed on top with a knife action mid-bar, and another pole then lifted into place, and on the first bang the poles butt together with the joiner.
As the depth increases, the amount of penetration reduces.
This single foundation point took 3 and half poles before the bottom of the first was making the ground under my feet rumble a bit, meaning solid ground. So it would have been roughly 28m or about 90 feet down to solid ground.
This foundation would take hundreds of foundation points multiplied by 3-4 poles each and weeks to complete.
Then the poles are resting on solid ground and cut off low, and the concrete basement is laid resting on all the pole tops, so that (hopefully) the building doesn't sink.
See the ACTION up close.