Efficient finite element techniques for limit analysis of suction caissons under lateral loads

This paper documents the use of finite element analyses techniques to determine the capacity of suction caisson foundations founded in soft clays under undrained conditions. The stress-strain response of the soft clay is simulated using an elasto-plastic model. The constitutive model employed is the classical von Mises strength criterion with linear elasticity assumed within the yield/strength surface. Both two- and three-dimensional foundation configurations are analyzed. The three-dimensionality of the failure surface of the actual caisson requires that computationally intensive three-dimensional models be used. Suggestions are given on how to improve computational efficiency by using quasi three-dimensional Fourier analyses with excellent results instead of true three-dimensional analyses. The finite element techniques employed the verified against available classical limit solutions. Results indicate that both hybrid and displacement-based finite element formulations are adequate, with the restriction that reduced-integration techniques are often required for displacement-based formulations.