Inclusion of small-strain stiffness in monotonic p-y curves for laterally loaded piles in clay

The small-strain performance of offshore wind turbine (OWT) pile foundations under lateral loading is critical for the foundation safety and the fatigue analysis of superstructure but is less explored in recent studies. This work presents p-y curve analyses of monopiles in marine clay that account for complete nonlinear soil stress-strain relationship. Based on a small-strain stress-strain relation, Total-displacement-loading Extended Mobilisable Strength Design (T-EMSD) analyses are performed to interpret the pile-soil interaction. On the basis, an analytical p-y curve model is proposed. An elastoplastic constitutive model with small-strain non-linearity is developed, and then p-y curve validation against finite element simulations is carried out. Furthermore, by comparing to centrifugal test observations and existing p-y models, good agreement and noticeable improvement are shown. This paper provides industry engineers with a timely and effective approach for OWT foundation design, allowing for inputting soil characteristics measured at in-situ site and laboratory.