A laboratory system for single-point multidirectional loading and 3D motion reconstruction

Publication Title
A laboratory system for single-point multidirectional loading and 3D motion reconstruction

Abstract

This paper describes a specialised laboratory system that enables single-point multidirectional loading with real-time three-dimensional displacement monitoring. The rig combines a load cell, a low-friction 360° self-aligning swivel pulley, a rigid measurement platform, and three linear displacement transducers, and attaches to an XYZ rectilinear actuator. In operation, the XY axes are used to position the Z-axis in plan relative to the foundation, and a single loading line running from the Z-axis around the rotating swivel applies general cyclic loading, via feedback control, to the foundation. Three-dimensional anchor head displacements are reconstructed via spherical-intersection (trilateration) applied to the linear displacement transducer data. System verification activities are presented, including (i) micrometre-imposed steps with 20 µm graduations and (ii) replication of a prototype anchor head trajectory derived from finite-element analysis scaled to centrifuge conditions. In both cases, reconstructed motions closely match the reference values with sub-0.03 (mm) errors. The apparatus provides a compact, line-of-sight-independent solution for enclosed soil boxes and centrifuge testing, enabling reproducible multidirectional loading and accurate 3D motion reconstruction. This technology is relevant to shared anchor design in floating offshore wind and other geotechnical challenges involving multidirectional cyclic loading.

Authors
Amin Rashidi Mehrabadi; Qiang Li; Jorge Mendoza-Ulloa; Benjamin Cerfontaine; David White; Susan Gourvenec

Published In

11th International Conference on Physical Modelling in Geotechnics (ICPMG2026)

Theme

Session 1: New facilities, new equipment, and measuring techniques