Static Load Test for bored piles 2

[AhmedJ.J.]

Hello everyone,

We have a structure with a basement of 4m under the surface level. The raft is obviously at -4m. The situation is that we want to test a test pile from the ground surface not from -4m. How could I neglect the effect of the skin friction or any other effects arising from the 4m which will then be excavated?

Thanks in advance.

 

[PEinc]

You could to install the test pile through a temporary casing that extends from original grade to -4m. Do not fill the casing with concrete. However, you now would need to consider the 4m unbraced length of the pile or add some centralizers in the casing pipe to laterally support the pile without causing any frictional resistance.

http://www.PeirceEngineering.com

 

[EireChch]

This is not an ideal situation. The main reason is that based on the laws of soil mechanics, your load test will not reflect the actual response of the pile when you remove the 4m for the basement!

Doing a load test with the 4m of soil in place will increase your effective stress which will increase your end bearing and skin friction. This is only applicable to granular soils.

For cohesive the effect will be only minor.

However, regardless of soil you will have 4mn of elastic shortening that you need to also consider.