Numerical investigation of pullout capacity for inclined strip plate anchors in sand

Plate anchors have been widely regarded as one of the most efficiency solutions for offshore structures in deep sea. Most of previous studies focus on the vertical or horizontal plate anchors embedded in sand. However, after the caisson foundation is withdrawn, the vertical plate anchor rotates to a certain angle from the horizontal plane in the process of resisting tension, which makes the analysis of pullout capacity of inclined plate anchors in sand relatively complex. This study, by using two dimensional finite element (2D-FE) method, takes a deep insight on the behaviour of strip plate anchors with different inclinations in loose to dense sand. A modified soil model is adopted to explore the hardening and softening behaviour of medium dense and dense sand. The FE results show a good agreement with previous numerical results and centrifuge test data. A series of FE cases are conducted to explore the effect of embedment ratios, plate inclinations and sand relative densities on the pullout capacity of inclined strip plate anchors. A new equation is proposed to estimate the ultimate pullout capacity of strip plate anchors with different inclinations in different relative densities of sand, which serves as a guidance for engineering design of inclined strip plate anchors in sand.