Piling through revetment quarry run
Piling through revetment quarry run
(OP)
Concept design is for a secant piled wall to construct a seawater intake structure on an offshore reclaimed island. bored cast in situ piling is prevalent in the region and more importantly the equipment is available at the remote site.
Contractor is unable at this time to provide a detailed methodology for how he will cast the piles in the area of the island revetments consisting of armour rock underlain by quarry run cobble-boulders.
His latest proposal is to insert a geomembrane inside the temporary casing before pulling the casing. I cant find anyone who has come across this approach and am asking the contractor for detailed MS and case histories. I wondered if any peers on here had experience of this or had alternative approaches.
We have constructed steel tube grouted piles for bridge foundations elsewhere on the island however this required specialist equipment and wouldn't be suitable where we're looking to construct the secant pile wall.
TIA
Contractor is unable at this time to provide a detailed methodology for how he will cast the piles in the area of the island revetments consisting of armour rock underlain by quarry run cobble-boulders.
His latest proposal is to insert a geomembrane inside the temporary casing before pulling the casing. I cant find anyone who has come across this approach and am asking the contractor for detailed MS and case histories. I wondered if any peers on here had experience of this or had alternative approaches.
We have constructed steel tube grouted piles for bridge foundations elsewhere on the island however this required specialist equipment and wouldn't be suitable where we're looking to construct the secant pile wall.
TIA





RE: Piling through revetment quarry run
RE: Piling through revetment quarry run
I've called the contractors sub-contractor to explain in detail this week.
RE: Piling through revetment quarry run
RE: Piling through revetment quarry run
RE: Piling through revetment quarry run
We have already drilled through revetment elsewhere, using bauer spezialtiefbau piling equipment however this work was installing steel column grouted piles. Obviously the steel column also acts as casing to retain the grout during casting.
However to install a secant pile wall we cannot use steel column piles as the boring of the secondary pile has to reem out the overlap with the primary piles. Therefore without the steel column acting as sacrificial casing how are we to bore and then cast the pile.
Bored cast in situ piles are usually cased through superficial deposits but the casing withdrawn almost immediately after concrete pouring, in our scenario that would allow the concrete to flow out through the quarry run. The current proposal is to line the temporary casing with a membrane to retain the concrete once the temp. casing is lifted, something I nor my colleagues have come across or like the sound of.......
hope that clarifies for those kind enough to be participating
TIA
RE: Piling through revetment quarry run
RE: Piling through revetment quarry run
Now if you drilling problem is solved, and I'm far from being convinced, limiting the overbreak can be achieved with pre-grouting ( rigidify the grout with sodium silicate to limit the quantities) or use a thin wall lost tube like COFRATOL )
With a geotextile you can't guarantee there won't be any necking in the pile.
RE: Piling through revetment quarry run
RE: Piling through revetment quarry run
I have no applicable experience, but it seems that you just need to know how strong the geotextile must be to contain the concrete across the biggest voids. You can estimate the void size as some fraction of the rock size and apply the formula for tension in a spherical pressure vessel, using the static head of the fluid concrete. Add a safety factor because the "bubbles" will not all be spherical. I think it is worth a try. Second question is whether the bit will cut the geotextile or try to pull it out when you drill the intermediate piers. You may need to wait a little longer before drilling.
A different approach might be to cast the pier with coarse, lean, zero-slump concrete and no steel, then re-drill it after the concrete sets.
RE: Piling through revetment quarry run
aeoliantexan, it is a secant pile wall. There will be no reinforcement in the female piles which are cast first.