Effect of soil remoulding on loss of embedment and bearing capacity of square plate anchors in clay

Abstract

This paper investigates the keying behaviour and capacity of square plate anchors in clay through three-dimensional large deformation finite element (LDFE) analysis. Strain rate dependency of the undrained shear strength and shear induced remoulding of clay (strain softening) are accounted for. The current LDFE results are first validated against existing centrifuge test data, theoretical and numerical results; with good agreement obtained. The soil remoulding effect on the anchor behaviour is then explored varying soil strength heterogeneity, soil sensitivity, anchor embedment ratio after installation, load eccentricity, and load inclination at the mudline. The clay surrounding the anchor undergoes significant remoulding during keying, resulting in a significant reduction of anchor embedment depth and capacity under subsequent loading. Design expressions and charts are proposed for assessing loss of embedment and ultimate bearing capacity. The keying behaviours of square plate anchors are compared with existing those of strip plate anchors. The square anchors show higher capacities and lower loss of embedment in both uniform and normally consolidated clays, which demonstrate that a simple shape factor cannot be applied from strip to square plate anchors.