Pile Construction in Porous Rock
Pile Construction in Porous Rock
(OP)
I have a question about secant bored pile construction:
The secant piles (of 10-15m long) are supposed to be constructed in a layer of rock which is porous and low compressive strength. Another constraint is the water table is very high.
Does anybody know there is any method of keeping the borehole dry during concreting if bentonite is not allowed to use?
The secant piles (of 10-15m long) are supposed to be constructed in a layer of rock which is porous and low compressive strength. Another constraint is the water table is very high.
Does anybody know there is any method of keeping the borehole dry during concreting if bentonite is not allowed to use?





RE: Pile Construction in Porous Rock
RE: Pile Construction in Porous Rock
RE: Pile Construction in Porous Rock
I would say that for most contractors a 30 foot tall wall is approaching the limit for a high quality end product.
RE: Pile Construction in Porous Rock
RE: Pile Construction in Porous Rock
Why not use a pressure tremie that starts at the bottom.
RE: Pile Construction in Porous Rock
The casing "stiffens the drill string and limits bit wander.
I would be very careful using uncased secant piles to this depth. Very good drilling in an uncased hole would be expected to wander at least 1%. Therefore at 15m depth you should expect at least +/- 150mm wander from pile head. This results in the "windows" mentioned in previous posts.
On a recent project, we found a maximum horizontal wander of only 30mm between adjacent piles. This makes placing the walers a breeze, instead of cutting back, chocking and wedging. This was in sands overlying low strength sandstones.
Good luck.