CPT-based method to determine the lateral capacity of monotonically loaded rigid piles in sand

Abstract

Monopiles are commonly used as foundations for offshore wind turbine generators (WTGs). Due to the rapid growth of the offshore wind energy sector, there is increasing demand for WTGs of larger capacities which evidently leads to demand for monopiles with larger diameter. An industry standard approach for assessing pile lateral response is the p-y method; however, this method was initially developed and empirically validated for long slender piles and thus its applicability to large diameter monopiles is doubtful.

The joint academia-industry project, Pile Soil Analysis (PISA) project resulted in an improved understanding of the lateral loading response of large diameter monopiles. Based on pile load test (PLT) data and numerical modelling, a method was developed to derive all soil reaction components from advanced finite element method (FEM) calculations to be used in a one-dimensional (1D) design framework.

Cone penetration test (CPT) based approaches have been shown to provide excellent predictions for the response of laterally loaded flexible piles where the p-y response dominates. In this thesis an approach to determine the additional components of the soil reaction curves for rigid monopiles, namely the side and base shear and base moment directly from the CPT is proposed. The results are compared to soil reaction curves are extracted from 3D FEM models, and compared to field tests on monopiles in sand