Modelling combined loading of piles with local interacting yield surfaces

The current design practice for piles subjected to inclined loads is to consider the axial and lateral pile behaviour separately. Each of these directions is represented by a separate differential equation that is solved independently. However, this procedure does not consider the combined effects of the different load directions. In this paper these differential equations are coupled using a concept of local interacting plasticity models and are thus solved simultaneously to determine the behaviour of a pile subjected to combined loading. The coupling is introduced using the concept of local elasto-plasticity yield surfaces, simulating the interaction between the soil responses in the two perpendicular directions. At this stage of the work elliptical yield surfaces have been incorporated. Although an ellipse may not be the ideal shape, it still enables several well-known physical observations to be captured. This model can be refined in the future to represent the local response of soil more accurately. © 2005 Taylor & Francis Group.