Machinery Outrigger on soil and gravel

[aschaefers]

My client requires me to provide analysis of a machinery outrigger on two types of surfaces, a 3 layer gravel road, and drained soil. He is not specific as to the makeup of the road, or they type of soil, as he is looking for a general performance range for his device. I'm assuming that as more compressive load is applied to the outrigger, at some point the soil will begin to shear around the edges of the outrigger. I'm not sure how to characterize the failure on gravel. I'm looking for a reference to help me with the failure criteria in both of these situations. I would appreciate any advice you have for me.

 

[chicopee]

Crane outrigger pad block should be 3X the area of the pad. Also see my attachment for aditional information.