Pile freeze

[chaslupe]

I am being told by the geotech engineer for a deep foundation project that by driving reaction piles near a driven test pile (that has been assumed to have experienced freeze over 2+ weeks) that the freeze was broken by driving these reaction piles thus causing the test pile to fail during the static load test. Does this make sense?

 

[eric1037]

How long after driving the reaction piles was the load test performed? If it was a short time, it is possible that pore pressures had not dissipated and the test pile was affected.

In clay soils, I have also experienced a phenomenon in which the adjoining piles heave up the test pile. This is especially true for displacement piles such as pipe piles.

 

[chaslupe]

We are using a montube pile which is a fluted pile. The load test was performed three days after the reaction piles were driven.

 

[GeoPaveTraffic]

It is possible that the capacity of the test pile was influenced by driving the reaction piles. The only way to know for sure is to do another load test.

 

[MRM]

I agree that driving the reaction piles could affect the test pile capacity (i.e. cancel pore pressure dissapation already completed, cause test pile heave/movement). The amount of capacity reduction would definately depend on the soil type. It's usually best to install the reaction piles and test pile at the same time. All piles can then set-up together.

 

[chaslupe]

Thanks all....as a result we are driving the additional test piles at the same time as the reaction piles to avoid this issue.

 

[eric1037]

You may also want to install the test pile last to reduce heave issues.

 

[DRC1]

You should be able to let the pile set and retest the pile rather than drive new piles and build a new load test. I would also check your load test set up and data to eliminate any other causes. If you do drive new piles I would moniter with a PDA to et a preliminary result.

 

[eric1037]

If you re-use the existing piles, I would recommend retapping them.