Pile Construction

[faisal45]

Dear All,
i designed a pile which dia is 20", length = 50'-0".
but the problem is when site engineer is doing construction caving occurs.
he told me caving length is almost 5'-0". they use 11 bags cement instead of 18.5 bags.
what should i do now? cancel it and design another pile??

Faisal

 

[dik]

What is the soil type? Can the pile be sleeved? and is there a geotekkie involved? why is the pile caving?

Dik

 

[faisal45]

soil type is gray color dense to very dense coarse to very fine sand & trace silt.
well dik you can take it as mismanagement & insufficient construction experience of site engineer.
these problems has been solved.
Thank you.
Faisal

 

[Ron]

faisal45...please describe your issue a bit more clearly.

Is this an augered concrete pile? How does he know that the caving length is 5'?

Should you abandon the pile? How many piles are there? Is this one pile in a group or is this a single pile? What is the soil profile? As dik asked, is there a geotech involved? What type of monitoring was done?

When you say 11 bags of cement vs 18.5 bags, I'm confused...are you saying the mix design contains 11 bags of cement? If so, that's a lot of cement in a mix design.

 

[Zambo]

Is it 11 "batch" of cement not 18.5? If so what volume is a batch?

 

[faisal45]

For ALL,
Its a cast -in-situ pile and we are using wash boring method.
caving length 5'-0" is approximate. they couldn't drive casing in full length.they just assume by this. in my opinion when they faced casing driving problem, they should pull up the casing & do boring properly again. but unfortunately they didn't. so my question is what should be the solution now as they did the casting.
There are 4 piles under one pile cap. 2 piles placed diagonally have caving problem. The construction is going on in a very rural area where no geotech is involved there.
Estimation report says that for one pile require 18.5 bags cement (considering mixing ratio 1:1.5:3). but in the field where caving occurred for those 2 piles they use 11 bags cement.
Feel free to ask me any kind of question.

Thank you.
Faisal

 

[Zambo]

Faisal45, I have never seen wash boring carried out for a pile of this diameter (in fact for any diameter of pile, I have only seen wash boring for soil invetsigation).

What is the process? I understand you have a full depth casing and you need to advance that (by wash boring) but what is the other system to advance the casing, do you use a hammer on the top of the casing or drop a baling bucket inside the casing?

But that is the point where I stop understanding. If using the wash boring technique then I think the casing has to be full depth and permanent. But then the cave in would be creating voids on tbe outside face of the casing (creating a problem with the friction capacity of tbe pile) but you are reporting a reduced amount of concrete which is a different problem.

It sounds as if the casing was just not driven deep enough.