Numerical investigation of the monotonic drained lateral behaviour of large-diameter rigid piles in medium-dense uniform sand

This paper presents a numerical investigation of the monotonic lateral response of large-diameter monopiles in drained sand with configurations typical of those employed to support offshore wind turbines. Results from new centrifuge tests using instrumented monopiles in uniform dry sand deposits are first presented and used to illustrate the suitability of an advanced hypoplastic constitutive model to represent the sand in finite-element analyses of the experiments. These analyses are then extended to examine the influence of pile diameter and loading eccentricity on the lateral response of rigid monopiles. The results show no dependency of suitably normalised lateral load transfer curves on the pile diameter and loading eccentricity. It is also shown that, in a given uniform sand, the profile with depth of net soil pressure at ultimate lateral capacity is independent of the pile diameter because of the insensitivity of the depth to the rotation centre for a rigid pile. A normalisation method is subsequently proposed which unifies the load-deflection responses of rigid piles with different diameters at a given load eccentricity.