The interaction of thin metal plate and circular rigid boulder in undrained clay: 2D physical and numerical models

Progressive buckling of thin-walled open-ended piles can occasionally occur during installation, especially when the pile penetrates through hard materials, or where there are subsea obstructions, typically in clays, such as boulders. The distortion initiated at the pile tip due to a boulder collision can propagate and lead to premature refusal of the pile as the installation proceeds, which can be expensive to remediate. The reliability of numerical simulations of such problems requires further consideration, due to the lack of test cases for validation. This paper presents plane-strain laboratory-scale physical modelling for the validation of numerical models relevant to progressive pile buckling problems, with the plate-boulder-soil interaction revealed by particle image velocimetry (PIV) analysis. A corresponding 2D numerical model employing the coupled Eulerian-Lagrangian (CEL) method in the software package Abaqus is used to simulate the experiments. This 2D model does not represent the pile buckling phenomenon directly but provides a benchmark for a numerical modelling procedure. The consistency of results between the physical modelling and the 2D numerical modelling gives confidence that, with the use of appropriate model properties, full 3D simulations would be capable of capturing progressive buckling phenomena for the advancing large-diameter monopiles that are used to support offshore wind turbines.