Adhesion between concrete and soil

[salman85]

Hi everyone,

i have a confuse while checking foundation analyse made by our consultant..
the foundation will be construct above sand layer, is there any adhesion between concrete and sand?
if i'm not wrong, adhesion only consider when foundation support by cohessive soil..
Some engineer neglected the adhesion factor, some engineer calculate this with reduction factor..

 

[Mccoy]

Salman, as far as I know usually adhesion is contemplated in lieu of the fricitonal term sigma*tan_phi when cohesive soil is underneath the base of the foundation (to check for the lateral displacement ultimate limit state).
So, as you say, adhesion should be equalled to zero if a purely frictional soil lays underneath the foundations.
Besides, even with phi-c soils, in lateral displacement ULS analyses much often the cohesion term is ignored.
The above if there is no ambiguity on the term 'adhesion'.

 

[Ron]

There is no adhesion, but there is friction if you are considering lateral movement of the foundation.

 

[salman85]

thanks Mccoy and Ron, you both right