Shear strength - Pile Testing Hi

[Simon G]

Shear strength - Pile Testing

Hi, Not a Geotech Engineer but looking at some results. Im just wondering if any relationship can be drawn between the results gained from doing a shear vane test (or Scala Penetrometer) to the results you might get in an uplift pile test (affected by soil type, skin friction and surface area)

Is there a graph that could be created that shows some correlation (even if rough) between geotech results and what uplift results you could expect, for a specific surface area of a pile?

From the the geotech results, this graph would guide how deep to to drive the pile before testing it, recognising you could always drive the pile deeper and retest.

Thanks in advance

 

[geotechguy1]

It sounds like you are in NZ. How long are your "Piles". I've found alot of people call a 1m long post here a 'pile' here which is a bit disingenous.

 

[EireChch]

There are no graphs per say, but vane shear tests would give you undrained shear strength which can be used to calculate skin friction. Depending on soil strength, skin friction is approximately 0.4-0.6 times Cu (from memory, check a text book).

As you are in tension you need to take approximately 70% of your skin friction calculated in compression.

Scala / dcp to get skin friction is very crude. You need a geotech to advise on a correlation that is safe to use.

 

[Simon G]

Hi guys

the piles are 4m long with about 2.5m to 3.5m in the ground depending on the results.
thanks for your comments.