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An approach for undrained geotechnical problems accounting for the development of partial saturation
No full textA mathematical programming approach is discussed for the finite element analysis of two-phase undrained problems in the field of geomechanics. This approach enables us to account for the possible development of partially saturated zones in the geotechnical medium, due to the attainment of a given lower limit in the
pore pressure distribution. Two alternative formulations are presented, both of them in terms of linear
complementarity and quadratic programming problems, and the computational advantages of one of them
are illustrated. The main characteristics of a step-by-step solution technique are presented. Finally, the solutions of some test problems are discussed and compared with those deriving from the traditional analyses in which the development of partial saturation is neglected
Numerical integration of an elastic-viscoplastic constitutive model for dry metamorphosed snow
No full textA constitutive model for dry metamorphosed snow is proposed, within the framework of elastoviscoplasticity, which is able to reproduce the most relevant features of the macroscopic behaviour of snow, particularly its time and rate dependency. The basic ideas for modelling stem from the conceptual forms proposed for bonded geomaterials, such as cemented soils or soft rocks. The high viscosity of snow is accounted for by adopting an overstress approach, suitably modified. An evolution law for the
curvature-driven process of sintering, by which intergranular ice necks form and grow, is established. The system of constitutive equations is then numerically integrated via a fully implicit time stepping scheme. Selected results from finite element simulations of laboratory tests, available in the literature, are presented
Condizioni analitiche per l'individuazione di punti critici e punti limite nel problema elastoplastico incrementale discreto
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