The failure mechanism of pile foundations in non-cohesive soils

In 1920 Prandtl published an analytical solution for the bearing capacity of a centric loaded strip footing on a weightless in-finite half-space, based on a so-called Prandtl-wedge failure mechanism. Meyerhof and Koppejan extended the logarithmic spiral part of the Prandtl-wedge and presented this as the failure mechanism for the tip of a foundation pile in non-cohesive soils. The numerical calculations made in this article show however that the failure zone (plastic zone) below a pile tip, is far wider and deeper than the Prandtl-wedge and that there is failure both in and out of the standard x-y plane, but most of the failure is due to an out-of-plane, circumferential or cleaving failure mechanism. Therefore, this failure mechanism is differ-ent from the Prandtl-wedge failure mechanism. Around the pile tip, there are circular thin zones with no out-of-plane failure. In these thin zones, the tangential (out-of-plane)