The behavior of granular materials is characterized by strong nonlinearity and irreversibility. If the definition of a proper constitutive model is of concern, an accurate experimental investigation of the nature of the incremental response is recommended, at least in order to allow for a selection among the several classes of constitutive relationships that can deal with such leatures. ln parallel with laboratory tests, discrete particle methods can be employed, as it was first suggested by Bauntr Sc PnouanT [l989]. ln this paper, the incremented behavior of granular soils is investigated by nume-

rically simulating stress probing experiments on a BD Distinct Element model consisting of a random assembly of spheres.

The reliability of such a model as a substitute for real granular materials is first discussed by reproducing experimental results presented by Rorrs & Dorint! [1998]. Then, the incremental behavior of the numerical model is studied by performing a series of axisymmetric stress probes of varying direction. Different initial states are considered, in terms of stress and previous loading history. The results obtained when starting from a virgin state show that classical plasticity with a single plastic mechanism is able to describe the increntental behavior quite satisfactorily. On the contrary, stress probing from a preloaded state indicates major deviations of observed response from the paradigm of both classical and Bounding Surface plasticity.

    The behavior of …

AUTORI: Calvetti F., Viggiani G., Tamagnini C. RIG ANNO: 2002 NUMERO: 3 Numero di pagina: 11



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