Analysis of Pile in Group

[L4Legit]

Hi All.

I would like to hear your opinions regarding the above subject. The situation is as below:-

1) During piling, by chance eccentricity occurs which exceeds the allowances specified by the Engineer and as a result, in a group of piles, for examples 9 piles, one or two piles exceeded their working load. Is adding additional pile the only option to rectify?

2) When this kind of eccentricity occurs, is it really the fault of Contractor? What if the cause is because of the machine or the site? How could we decide the cost of rectification shall be bear by Contractor?

3) Refer to (1) what if the Engineer choose to go with adding pile, however, due to additional cost the Head did not allow to add pile, instead to just go with adding additional rebars etc. As the Engineer stay firm with his decision to adding pile, would it be right for him to ask to Head to ask other Consultants to propose another solution - to design, to sign and to stamp their proposal?

This is what I usually heard happened in the industry in my area. To prevent additional cost or of course, they want to keep the Client happy, they disregard Engineer's proposal.

Thank you for your input.

 

[SlideRuleEra]

These are my comments:

1) - If the problem is discovered while the pile driver is still working on the job, adding a pile is usually both the least expensive and best technical solution.

2) - Negotiate a settlement (include the Contractor in the negotiations). There can be combination of reasons for the problems. If so, split the extra cost among the parties.

3) - This "mess" may have been avoided if the Contractor had been asked what he wanted to do. A reputable Contractor will sometimes accept the extra cost just to keep work moving. It is very expensive for a Contractor to "sit around" while others squabble over what to do.

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[msquared48]

If they disregarded my solution to the problem and there no other valid solutions, I would seriously consider removing myself as the EOR.

Mike McCann, PE, SE (WA)

 

[hokie66]

There may not be a viable solution "with adding additional rebars, etc". Any chance the column can be shifted closer to the centroid of the pile group?

 

[TLHS]

On a nine pile group, it would surprise me if you can't eat a little extra eccentricity with minor redetailing. If the issue is the capacity of the pile itself, load redistribution will likely take care of it. It depends on what the system looks like, though. If the piles are at structural capacity, or on bedrock you might not get redistribution. If they're on bedrock, though, you can also probably call up the geotech and get them to sign off on a bit of extra capacity. If piles are going to slip, then you'll likely redistribute loads.

There are definitely cases where you can't make it work, though. It also might be more expensive to stop and figure out if you can make it work than to just put another pile in. The incremental cost of a pile is going to be cheaper than the engineering cost of rechecking things, plus the standby cost for the contractor to stand around waiting for people to work things out.

Whether it's the contractor's cost will depend heavily on the contract stipulations, information available to the contractor prior to the start of work, and actual field conditions. Not a lot we can tell you about those.