Arching Effect in Sand

[1967pradyot]

Hi

In case of determination of pile capacity in cohesionless soil generally it is considered that overburden increases linearly upto a depth of 15-20D (D being the pile diameter). Beyond which it's become constant. It is established from laboratory and field tests that this is happened due to "Arching" effect in sand.
I would like to know the fundatmental mechanism of "Arching" phenomenon in cohesionless soil in case of pile?

Thanks

 

[Focht3]

There isn't one - this is generally assumed to be a remnant of the installation process.

By the way this "assumption" is not universal in its' use -