Large deformation numerical analysis of the ultimate pullout capacity of plate anchors in sand

摘要

Plate anchors are commonly embedded deeply in the seabed toefficiently provide the pullout capacity. The ultimate pullout capacity(UPC) of the anchor is an important index in engineering. Reliableprediction of the UPC requires the failure mode of the anchor wellunderstood. Large soil deformations will occur when the anchor ispulled out of the soil. It is difficult for the classical finite elementmethod to simulate the pullout process due to a loss of accuracy andnumerical divergence. In the present work, the coupled Eulerian–Lagrangian (CEL) approach, which is one of most serviceable largedeformation finite element methods, is used to simulate the pulloutprocess of plate anchors. Considering the computational time andrelative simplicity compared to advanced constitutive models, theMohr-Coulomb constitutive model is chosen but modified to describethe sand behavior. For loose and dense sand, different functions areemployed to introduce evolutions of the friction angle and the dilationangle. The calculated results are compared to centrifuge tests andexisted load-displacement curves. It is demonstrated that the CELmethod combined with the modified Mohr-Coulomb constitutive modelcould successfully capture the uplift behavior of plate anchors in sand.The UPC of plate anchors is then determined by the maximumresistance criterion from the load-displacement curves. The failuremechanisms are also observed during the pullout process.