The Undrained Capacity of Shallow Two-Foundation Systems Acting in Consort Under Three-Dimensional Loading

Two-footing systems are used in the offshore industry to support a variety of subsea structures. This paper presents a three-dimensional numerical analysis of the undrained capacity of rigidly connected two-footing systems using a finite element approach. The model was validated against available relationships for uniaxial capacities and failure envelopes. The model was then used to investigate the behaviour of rigidly connected two-footing systems at various separations under general three-dimensional loading. It was observed that the uniaxial vertical, horizontal and longitudinal moment (My) capacity of two-footing systems is slightly affected by varying the spacing between footings. However, transverse moment (Mx) and torsion capacity oftwo-footing systems were significantly enhanced by increasing the spacing between footings.