A closed-form equation for the failure locus of pile groups subjected to generalized loading conditions

A closed-form solution for the failure locus of piled foundations in the force space is presented and discussed. Based on recent works published in the literature dealing with the problem of the bearing capacity of pile groups under inclined eccentric load, the expression of the failure locus is derived by combining a parabola in the vertical force – moment plane and a Granville egg in the vertical force – horizontal force plane. The complete three-dimensional failure surface requires only a few parameters that can be evaluated even by hand calculation through simplified methods existing in literature. The predictive ability of the proposed equation is validated against the data available from previous works on piled foundations subjected to inclined eccentric loads.