A study of localized deformation pattern in granular media

Shear localization in granular materials are studied numerically and compared with experimental results. General agreements are shown for the localization pattern in granular body behind a retaining wall in active and passive limit state and under a strip footing. Quantitative agreement is also shown for the limit load in strip footing. Numerical simulations are based on a micro-polar (Cosserat) continuum approach. An extended hypoplastic model is used for constitutive description of granular media, which includes rotational degrees of freedom for material particles and takes into account the effects of grain size and inter-granular friction. For a more realistic modeling of material response, fluctuation in state variables are introduced based on physical argument. It is shown through numerical examples that realistic localized deformation pattern can be initiated with a fluctuation in initial density.