Coupled analysis of full flow penetration problems in soft sensitive clays

Abstract

This study describes the development and implementation of a numerical procedure for the analysis of coupled geotechnical problems involving finite deformations, changing boundary conditions, multiphase porous media and softening behaviour. The numerical scheme is first validated through a benchmark problem concerning the laying of an on-bottom offshore pipeline, and then some further highlights of the effects of soil softening are presented. The scheme is then specifically employed to study the penetration process of a full flow cyclic T-bar test in soft sensitive clay. An advanced soil constitutive model has been implemented to capture the effects of soil structure and its progressive de-structuring as well as soil fabric anisotropy. Accordingly, the changing soil resistance due to the combined effects of soil softening, remoulding and reconsolidation is illustrated, by considering a T-bar undergoing large amplitude cyclic sequences interspersed with consolidation periods. The results from the numerical simulations reveal the effects of soil softening on the soil deformation pattern, the evolution of shear bands, the generation of excess pore pressures and the process of soil reconsolidation.