Bored piles are large-diameter (1 to 2 m) concrete foundation elements that are cast in-situ and can be installed up to great depths. Very suitable for transferring large concentrated loads (20 MN is feasible) into the soil. These piles are produced using a heavy-duty rig with a rotary drill that rotates a telescopic kelly bar with an auger or bucket drill. The stability of the bore hole is maintained by applying bentonite or water depending on depth and circumstances. To guide the drilling equipment and protect the pile head, an auxiliary the topsoil over the first couple of metres. After cleaning the rebar cage can be positioned and concrete can be poured. This is done using a tremie pipe in order to fill the bore hole from the bottom. During the pouring the tremie pipe is shortened and the bentonite is pumped away. Before curing of the concrete can occur the casing is removed from the top of the pile.
These piles are used for transferring large concentrated loads at larger depths, such as for tall office buildings, silos, bridges and viaducts. They can also be used as a substitute for multiple piles underneath a column base.
Top-down construction is possible by combining bored piles with prefab concrete columns.
The (auxiliary) equipment that is needed and the resultant footprint are relatively large. These include a bentonite plant, vehicles for transporting the concrete to the pile, and storage for the rebar cages.
|
Name of project |
Client |
|
Rotterdam Maasvlakte, Construction pit Electrabel powerplant |
Visser & Smit Bouw |
