Modelling soil-water interaction with the Material Point Method. Evaluation of single-point and double-point formulations

Many problems in geotechnical engineering involve large deformations and soil-water interactions, which pose challenging issues in computational geomechanics. In the last decade, the Material Point Method (MPM) has been successfully applied in a number of large-deformation geotechnical problems and multi-phase MPM formulations have been recently proposed. In particular, there exist two advanced coupled hy-dro-mechanical MPM approaches to model the interaction between solid grains and pore fluids: the single-point and the double-point formulation. The first discretizes the soil-water mixture with a single set of ma-terial points (MP) which moves according to the solid velocity field. The latter uses two sets of MP one for the fluid phase and the other for the solid phase and they move according to the respective velocity field. The aims of this work is to present and compare the two theories, to emphasize their limitations and poten-tialities, and to discuss their applicability in the geotechnical field. To this end, the results of two numerical examples carried out by using both formulations are presented: a 1D-consolidation problem and a saturated column collapse problem.