We analyze statistical properties of quasi-statically sheared granular media by means of particle-scale numerical simulations. ln particular, we show the following: 1) The average contact direction does not always capture the directional organization of interparticle contacts which might involve several peaks in different directions; 2) The evolution of the granular micro-structure is strongly coupled to the mean coordination number. In particular, we find a saturation of contact grain in dense systems and a saturation of contact loss in loose systems; 3) The general incompatibility of a uniform strain field, applied at the boundaries or in the bulk, with mutual exclusions of the particles generates a fluctuating particle displacement field with a wide (stretched exponential) distribution at small strain increments; 4) These fluctuating displacements display multiscale correlations characterized by the power-law shape of their power spectra in space; 5) The contact forces are characterized by the occurrence ofa large number ofweala forces with a nearly uniform distribution and the exponential fall of the number of stronger forces; 6) By means of an additive decomposition of the expression of the stress and fabric tensors, we find that the weak contact set, comprising the contacts carrying a force below the average force, does not contribute to the transmission ofshear stresses and it tends to be perpendicular to the strong contact set.
We analyze stati …
AUTORI: Radjai F., Troadec H., Roux S. RIG ANNO: 2002 NUMERO: 3 Numero di pagina: 39
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