a b s t r a c tGeotechnical applications often involve large displacements of structural elements, such as penetrometers or footings, in soil. Three numerical analysis approaches capable of accounting for large deformations are investigated here: the implicit remeshing and interpolation technique by small strain (RITSS), an efficient Arbitrary Lagrangian-Eulerian (EALE) implicit method and the Coupled Eulerian-Lagrangian (CEL) approach available as part of commercial software. The theoretical basis and implementation of the methods are discussed before their relative performance is evaluated through four benchmark cases covering static, dynamic and coupled problems in geotechnical engineering. Available established analytical and numerical results are also provided for comparison purpose. The advantages and limitation of the different approaches are highlighted. The RITSS and EALE predict comparable results in all cases, demonstrating the robustness of both in-house codes. Employing implicit integration scheme, RITSS and EALE have stable convergence although their computational efficiency may be low for high-speed problems. The CEL is commercially available, but user expertise on element size, critical step time and critical velocity for quasi-static analysis is required. Additionally, mesh-independency is not satisfactorily achieved in the CEL analysis for the dynamic case.

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Monopiles used as foundations for offshore wind turbines can be installed using different methods including jacking, vibratory driving and impact driving. Significant research efforts have been dedicated to the characterisation of monopile−soil interaction under lateral loading, mainly using p–y curves. There has also been extensive research in quantifying the effect of different installation methods on the axial response using numerical modelling and physical modelling techniques. Little attention has been paid to the effect of the installation method on the subsequent lateral response of a monopile under the in-service condition. In this paper, a purpose-designed apparatus is described that allows in-flight installation using different installation methods followed directly by lateral loading without stopping the centrifuge and thus retaining the installation-induced stress state. Test results from three lateral loading tests are discussed, with the piles either jacked at 1g and Ng or impact driven at Ng into a dry medium dense sand, allowing the effect of the installation method on the initial stiffness and ultimate capacity to be examined. The successfully conducted tests illustrate the capabilities of the new apparatus for centrifuge testing of laterally loaded driven piles.

Les études en laboratoire de la réponse de fondations peu profondes n'ont jusqu'ici pris en compte que la charge planaire. Cet exposé décrit les travaux expérimentaux effectués en utilisant un dispositif de charge qui applique une charge générale à deux modèles de fondations peu profondes. La charge, qui met en oeuvre les six degrés de liberté [verticale (V), horizontale (H 2 , H 3), torsion (Q) et moment de retournement (M 2 , M 3)], a été appliquée à une fondation plate circulaire de 150 mm de diamètre dans un sable de silice sec et meuble. Nous décrivons brièvement les aspects de cette installation mais ce qui importe vraiment est la présentation des résultats expérimentaux. Ceux-ci fournissent une preuve en faveur de la généralisation des modèles existants de plasticité durcissant à froid des conditions de charge planaire sous condition de charge générale. Cette preuve est utilisée pour élargir un modèle numérique existant au cas de liberté de six degrés ; les résultats de la simulation sont comparés aux résultats expérimentaux.

Incidents of unpredicted, and often adverse, jack-up foundation performance continue to occur regularly, while the safety records of other jack-up activities, such as towing, drilling, structural fatigue, collision, fire and blow-outs have improved significantly. Even with comprehensive site assessment procedures in place, and at a time when the jack-up industry is increasingly focused on the control of risks, foundation incidents continue to occur.