Differential Settlement for Foundation Design

[ivanga7]

Hi all. I'm working on a project where I have to design masonry site walls. The geotechnical report for this development states that "a total settlement of 2.4 inches and differential settlement of 1.2 inches over a 30-foot horizontal distance should be considered for foundation design." What exactly should I be designing for? The walls don't really carry any load other than their self weight, however, 1.2 inches of differential settlement seem a lot. Thank you for your help.

 

[Agent666]

Is the differential settlement due to a significant change in soil properties across the width/depth of the building? Or an offshoot of the possible differences in loading and foundation types? Each dealt with or considered quite differently!

 

[ivanga7]

It's due to the "moderate collapse potential in the underlying alluvium"

 

[Agent666]

Stepping back for a second to look at the big picture, I'd think for a retaining wall and the bearing forces being not constant across the width of the footing (as it resists overturning) I'd think any settlement of the ground would equate to rotation of the wall. Perhaps a significant amount of rotation which if acting away from the retained soil has the significance of allowing for significant settlement of the ground being retained.