Large-Scale Monotonic and Cyclic Testing of Gravel for Offshore Applications

Abstract

At a scale where particle size effects and specimen fabric are more realistically represented, the current concept provides insights that are otherwise difficult to obtain for coarse gravel materials. The present concept is demonstrated on a campaign including three monotonic and nine cyclic large-scale consolidated anisotropically drained triaxial tests conducted in a 50 × 50 cm triaxial cell. Monotonic tests are used to establish mobilized shear strength and stress–strain behaviour across a wide strain range and define a reference shear stress for cyclic testing. Cyclic tests capture stiffness degradation and strain accumulation under loading regimes relevant to offshore wind turbines. The paper demonstrates how representative parameters can be measured, and how the applied testing procedures influence the outcome of the testing. The applicability of hypothesis-confirmation testing in place of full investigative programs is addressed in the light of reducing uncertainty in parameters and improving confidence in the assessment of gravel beds supporting offshore wind gravity-based foundations.