Penetration of dynamically installed anchors in clay

TLDR

The study uses centrifuge data to investigate how dynamically installed anchors penetrate normally consolidated clay. An analytical embedment model, calibrated with centrifuge data and incorporating strain‑rate‑dependent shear resistance and fluid‑mechanics drag, was developed to predict anchor penetration. Anchors without flukes embed two to three times their length at 30 m/s, with depth mainly governed by anchor density; total energy provides a robust metric for comparing different anchor designs, and the calibrated model predicts field embedment within 4 %.

Abstract

This paper utilises centrifuge data to explore the penetration response of dynamically installed anchors in normally consolidated clay. The data indicate that for anchors with no flukes, expected anchor tip embedment depths are two to three times the anchor length for impact velocities approaching 30 m/s, with a strong dependence on the net density of the anchor and smaller dependence on the impact velocity. Total energy, defined as the sum of the kinetic energy of the anchor at the mudline and the potential energy released as it penetrates the seabed, is shown to be a useful quantity for comparing the embedment depth of anchors with markedly different geometries and mass, impacting the soil at different velocities. The centrifuge data were used to calibrate an analytical embedment model, based on strain-rate-dependent shearing resistance and fluid mechanics drag resistance. The merit of the anchor embedment model has been demonstrated by predicting the final embedment depths for a series of offshore field trials to within 4% of the measurements.