Minimum distance between the foundation for Passive Earth pressure

[allimuthug]

I have three Spread Footing Foundations FD1,FD2,FD3. The Height of the Foundations H = 1.5 meter.
The spacing between the Foundations are L1 and L2 = 0.5 meter.
My foundations are weak in sliding, hence I am taking the benefit of passive resistance of soil but you can see that the clear distance between the foundation is only 0.5 meter. Is it advisable to consider the passive resistance for each foundation as shown in the picture attached. Please give me the guideline for minimum distance between the foundations for considering passive resistance.

 

[fattdad]

from the lowest depth of the foundation, strike an angle that heads upwards at 45-phi/2. That's the soil influenced by Rankine passive pressure.

f-d

ípapß gordo ainÆt no madre flaca!

 

[oldestguy]

I'd give only the down movement foundations any passive resistance and add to that the sliding resistance of the whole block, foundations and soil between, assuming they are all tied together with a floor system..

 

[charliealphabravo]

A footing key can be added to increase sliding resistance if that is an option.