NUMERICAL MODELLING OF BEHAVIOR OF DRAG ANCHORS

WU XIAONI

Publication

NUMERICAL MODELLING OF BEHAVIOR OF DRAG ANCHORS

WU XIAONI

Abstract

Drag anchor is a commonly used economical anchor type in offshore engineering. Accurate prediction of the drag anchor trajectory is necessary and important for estimating the anchor final position and holding capacity reliably. The traditional yield envelope method of predicting the anchor trajectory used only the yield envelope from deep anchor behavior. The development of the method considering the shallow anchor behavior is still required as the anchor is actually dragged from shallow depth to deep depth. The current analyses focus on the anchor behavior under unidirectional and combined loading first. The effects of the anchor embedment depth ratio, anchor inclination angle, soil overburden pressure ratio, soil non-homogeneity and the anchor/soil interface condition on the unidirectional capacity and yield envelope are investigated. Based on the understanding of anchor behavior under combined loading, different ways of approximation of shallow anchor behavior are applied in the kinematic analyses to examine the effect of shallow anchor behavior on the prediction results. Comparison of results from kinematic analyses integrating shallow anchor behavior with the centrifuge results for two cases of drag anchor shows good agreement, which verified the importance of considering the shallow anchor behavior reasonably in the kinematic analysis.