Formula of critical edge load of strip foundation under complex stress state

The critical edge load, which is defined as the load strength on the ground when the plastic region just appears at the foot of a strip foundation, was proposed based on Mohr-Coulomb strength criterion. A formula of the critical edge load is modified based on the twin shear stress strength criterion, which is a three-dimensional strength criterion expressed in a linear form and is used widely in China now. Compared with the original formula, bigger value of the critical edge load can be calculated by using the modified formula for the effect of intermediate principal stress is considered in plane strain condition.