G-PFEM Numerical Assessment of Rock Anchor Interface Properties on Pull-Out Capacity for Renewable Offshore Applications

With the challenges faced by tidal stream generator application, it is necessary to develop a new generation of Rock Anchors (RAs) that are easy to install and efficient, with accurate, robust, and realistic design procedures. The harsh marine environment requires efficient anchoring solutions capable of sustaining the complex loading conditions experienced. Current RA technologies require simple and robust design methods to overcome the conservatism adopted in classical procedures. Therefore, advanced numerical methods have a crucial role to play in the enhancement of the RA design process. The Geotechnical Particle Finite Element Method (G-PFEM) is an open-source numerical tool suitable for large strain problems and is used herein to investigate the influence of steelrock interface properties on RA pull-out. A large deformation constitutive model for structured materials, calibrated to replicate the behavior of calcarenite and sandstone, is used to simulate the RA response under axial loading. The Contact Domain (CD) technique is described and was adopted for this work. The parametric analysis considering various combinations of steel-rock interface friction angle (δ), the inclination of the lateral face of the anchor (α) and contact parameters was performed. The results highlight how interface friction affect performance in soft and hard rocks. Due to the large deformation capabilities and the non-local formulation of the numerical approach the RA failure mechanism is realistically investigated.