A small-scale physical model for evaluating the axial response of Rock Anchors for offshore renewable applications

Rock Anchors (RAs) are a cost-effective solution to the expanding demand of renewable energy in the context of various deep-water applications. Novel anchoring systems designed for rocky seabeds require the development of simple installation procedures and reliable design methods under demanding loading conditions. In this work, a small-scale 1g physical test was developed to model the axial RA behaviour by means of pre-stressed anchor bolts installed in calcarenite rock. The load was applied through an UTM INSTRON machine, whilst a simple steel beam structure was adopted preventing vertical displacement of the calcarenite block. The failure mechanism and the load capacity under axial loading were experimentally assessed. The use of X-ray CT scans was found to be crucial in providing direct observations of installation effects and failure modes in the rock. The results presented in the paper can be used to validate the prediction of large-strain numerical models and develop rock-bolt interaction models to improve current design procedures.