Failed Driven Pile

[186]

I have a group of 4 piles driven for a square pile cap. One of the piles failed as proven by a PDA test( Pile Driving Analysis) conducted on that particular pile.

How should I rectify the problem? Should I drive two extra piles and redesign the pile cap?Could anyone suggest any textbooks that address this kind of problem.

 

[Ron]

Since only one of the 4 piles failed, it would be necessary to determine the probable cause of the failure. Which was it in the driving sequence? If last, I would worry about the others as well. Perhaps you punched a lense and weakened the group. Have you considered a load test of the whole cap?

As for you other questions, this is a "real" situation that usually doesn't appear in textbooks, though some of the older ones might contain it (Winterkorn and Fang, Terzhagi and Peck, Sowers, etc.). If you don't want to go through additional testing, then re-design the cap with a one or more additional piles to accommodate the deficiency.

I still think you should find the cause of failure first, though.

 

[austim]

186,

In addition to Ron's suggestions, have a very close look at the pile driving records for all four piles to see if the 'failed' pile behaved differently during driving.

'Failed' means different things to different people. To the pile testing fraternity it may mean "did not achieve the required test result". To construction engineers it may mean 'clearly broken'.

If the test merely says that the computed pile capacity is less than specified, try a re-test, and thoroughly examine the design calculations to see whether the design engineer has been unreasonably conservative.

Have any other piles on your project been tested? Is it possible that the actual PDA testing procedure has imposed an excessive load on your pile? If your piles are bearing on hard rock, an over-enthusiastic PDA tester (intending to generate some movement at the pile toe) can quite easily break a perfectly sound pile.

Good luck.