Uniaxial Undrained Bearing Capacity of Gravity Framed Suction Anchor in Clays

The finite element calculations of the gravity framed suction anchors, a new type of anchorage foundation, are carried out by using commercial software Abaqus. The effects of the dimensions and burial depth of the foundation and the heterogeneity of soil strength on the bearing capacity are analyzed under different loading conditions. Meanwhile, the failure mechanism of gravity frame suction anchors in homogeneous and non-homogeneous clays is studied under the conditions of vertical, horizontal and bending moment loads, and the improvement of bearing capacity by the frame and skirt plate depth, relatively to that by the traditional tripod frame suction anchors, is quantified. The results indicate that the gravity framed suction anchor with shallow embedment depth can increase the vertical, horizontal and anti-overturning bearing capacities due to that its frame enhances the mutual restraint effect of the suction anchor modules. With the increasing in the embedment depth the hoisting effect of the frame reduces gradually. When the reduction of the hoisting effect is greater than 15%, the depth of skirt plate becomes a primary contributor to enhancing the bearing capacity. Furthermore, based on the stable proportional relationship between the uniaxial bearing capacity coefficients of hexagonal and circular suction anchors, a simplified method is proposed for estimating the undrained uniaxial bearing capacity of the gravity framed suction anchor, providing a technical basis for a wide application of the anchor.