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The now-abandoned project for a new international airport for Mexico City was located at a site on the former Texcoco Lake, where extremely difficult subsoil conditions prevail. The behaviour of one of the trial embankments built to test foundation solutions for the runways is analysed in this paper. Observational data were gathered over 50 months at the so-called reference embankment, where no special foundation or soil improvement techniques were adopted. The performance of this embankment was investigated through finite-element simulations in which an elasto-viscoplastic constitutive model was implemented in commercial software. The model incorporates key features such as time dependence, long-term deformation and an anisotropic flow surface. The results provide an assessment of the constitutive description adopted as well as the role of anisotropy in the simulation of the case study. [ABSTRACT FROM AUTHOR]

Due to the extensive use of one-dimensional equivalent linear analyses to determine the free-field response of nonlinear soil deposits, dynamic numerical simulations able to reproduce an analogous response to equivalent linear codes are of great value for practical engineering, particularly for dynamic soil-structure interaction problems. An appealing alternative, for problems not close to a failure condition, is to assume a linear elastic behaviour of the soil but with stiffness parameters derived from one-dimensional equivalent linear analyses, i.e. consistent with the level of deformation induced by the input motion. In this approach, energy dissipation has to be artificially incorporated through material damping formulations. In this work, local, Rayleigh, and hysteretic damping formulations in FLAC were assessed to emulate results from one-dimensional equivalent linear analysis. A main feature of the analyses is that they consider a site having a considerably stratified soil deposit, in which the shear wave velocity profile displays significant variations and where the selection of some parameters in the damping formulations is not a trivial task. Results provide relevant insights into the performance of the adopted damping formulations and the selection of material damping parameters to reproduce results of equivalent linear analyses. [ABSTRACT FROM AUTHOR]

The undrained stability of slopes in anisotropic fine-grained soils is studied in this paper using the finite element method (FEM). A constitutive model is presented, able to account for the observed variation of undrained strength with loading direction. The model is able to encompass the different strength distributions observed in normally, slightly overconsolidated and heavily overconsolidated soils. A series of stability analyses have been performed to explore the effect of the type of undrained strength anisotropy on the stability and failure mechanisms of slopes of different inclinations. In addition, a real case study of the failure of an underwater slope is analysed with the numerical approach presented. It suggests that, by considering undrained strength anisotropy, the failure can be satisfactorily explained. [ABSTRACT FROM AUTHOR]