Embedded localization band in undrained soil based on regularized strong discontinuity—theory and FE-analysis

Abstract

The paper presents a novel approach to the analysis of a developing localization zone in undrained soil considered as a mixture of a solid skeleton and fluid-filled pores, where the solid phase is considered as elastic-plastic. The basic feature is the concept of regularized displacement and pore pressure discontinuities, which are assumed to occur across an internal discontinuity surface. In this respect the present developments are extensions of those suggested by Simo et al. (1993), Comput. Mech.12, 277–296, and, more recently, by Larsson and Runesson (1995), J. Engng Mech. ASCE (in press). A finite element formulation is proposed on the basis of a mixed variational formulation in the spirit of the “enhanced strain” concept by Simo and Rifai (1990), Int. J. Numer. Meth. Engng29, 1595–1638. In this fashion, the localization zone is embedded into a “base” element for the ordinary analysis of the (non-localized) mixture problem.