This book presents contributions to the 9th International Workshop on Bifurcation and Degradation in Geomaterials held in Porquerolles, France, May 23-26, 2011. This series of conferences, started in the early 1980s, is dedicated to the research on degradation and instability phenomena in geomaterials.

The volume gathers a series of manuscripts by brilliant international scholars reflecting recent trends in theoretical and experimental research in geomechanics. It incorporates contributions on topics like instability analysis, localized and diffuse failure description, multi-scale modeling and applications to geo-environmental issues.

This book will be valuable for anyone interested in the research on degradation and instabilities in geomechanics and geotechnical engineering, appealing to graduate students, researchers and engineers alike.

Inhalt
Preface.- Introduction.- Instability and bifurcation for inelastic geomaterials, by R. Chambon.- Part 1 Micromechanical origins and multiscale analysis of instabilities in geomaterials .- Deciphering D'Alemberts dream: new tools for uncovering rules for self-organized pattern formation in geomaterials, by A. Tordesillas and D. M. Walker.- Microscopic origins of shear strength in packings composed of elongated particles, by E. Azéma, F. Radjai.- Multi-Scale Analysis of Instability in Sand, by C. S. Chang, Z.-Y. Yin and P-Y. Hicher .- Observation of Microstructural Changes and Strain Localization of Unsaturated Sands Using Microfocus X-ray CT, by Y. Higo, F. Oka, S. Kimoto, T. Sanagawa and Y. Matsuhima.- Signature of Anisotropy in Liquefiable Sand under Undrained Shear, by J. Zhao & N. Guo.- Friction and localization associated with non- spherical particles, by A.V. Dyskin and E. Pasternak.- Length scales for nonaffine deformation in localized, granular shear, by A. L. Rechenmacher, Sara Abedi;Discovering community structures and dynamical networks from grain-scale kinematics of shear bands in sand, by A. Tordesillas, D. M. Walker, A. Rechenmacher and S. Abedi.- Slip and dislocation in crystalline solids as precursors to localized deformation, by R. I. Borja, H. Rahmani, F. Liu.- Part 2 Geo-environmental applications.- A Chemo-Thermo-Mechanically Coupled Behavior during Gas Hydrate Dissociation and its Numerical Analysis, by S. Kimoto, F. Oka, Y. Miki, T. Fukuda and H. Iwai.- Stability of nail reinforced boreholes, by E. Papamichos .- Stability analysis of creeping faults: the role of chemical decomposition of minerals, by J. Sulem, N. Brantut.- Onset of immersed granular avalanches by DEM-LBM approach, by J.-Y. Delenne, M. Mansouri, F. Radjai, M. S. El Youssoufi, A. Seridi.- Multi-scale periodic homogenization of ionic transfer in cementitious materials, by K. Bourbatache, O. Millet, A. Aït-Mokhtar .- Chimney of fluidization and sandboil ina granular soil, by P. Philippe and M. Badiane.- Experimental study of contact erosion at a granular interface, by R. Beguinabc, P. Philippe and Y-H. Faure.- Numerical modeling of hydrofracturing using the damage theory, by A. Guest and A. Settari.- Polydisperse segregation down inclines: towards degradation models of granular avalanches, by B. Marks, I. Einav and P. Rognon.- Numerical Modelling of Interaction between Snow Avalanche and Protective Structures, by M. Wawra, Y. Wang, W. Wu.- Crack propagations on the rock face at Glacier Point of the Yosemite National Park after the 1999 rockfall, by K.T. Chau and P. Lin.- Soil Machine Interaction: Simulation and Testing, by M. Alsaleh .- Part 3 Numerical modeling of failure and localized deformation in geomaterials.- Multiscale Semi-Lagrangian Reproducing Kernel Particle Method for Modeling Damage Evolution in Geomaterials, by J. S. Chen, P. C. Guan, S. W. Chi, X. Ren, M. J. Roth, T. R. Slawson, M. Alsaleh.- Tunnel excavation modeling with micromechanical approaches, by S. Levasseur, F. Collin, R. Charlier, D. Kondo.- Coupling discrete elements and micropolar continuum through an overlapping region in one dimension, by Richard A. Regueiro and Beichuan Yan.- On the numerical implementation of a multi-mechanism cyclic plasticity model associated to a dilation second gradient model aiming strain localization mitigation, by A. Foucault, F. Voldoire and A. Modaressi.- 2 D and 3 D modelling of geomaterials using a second gradient dilation model, by R. Fernandes, B. Ducoin and R. Chambon.- Local second gradient models for thermo-hydro-mechanical coupling in rock like materials, by Y. Sieffert, F. Marinelli, R. Chambon .- Two scale model (fem-dem) for granular media, by M. Nitka, G. Combe, C. Dascalu and J. Desrues.- Finite element modelling of material instability via an enriched elastoplastic model, by R. Wan and M. Pinheiro.- Comprehensive DEM study of the effects of rolling resistance on strain localization ingranular materials, by M. Gutierrez and M. Abdalsalam.- Modeling porous granular aggregates, by R. Affes, V. Topin, J.-Y. Delenne, Y. Monerie and F. Radjai.- Comparative modelling of shear zone patterns in granular bodies with finite and discrete element model, by J. Tejchman .- Influence of weak layer heterogeneity on slab avalanche release using a finite element method, by J. Gaume, G. Chambon, M. Naaim and N. Eckert.- Part 4 Failure, localization and multi-physical couplings.- Coupled mechanical-hydrological-chemical problems in elasto-plastic saturated soils and soft rocks using escript, by A. Mohajeri, H. Muhlhaus, L. Gross and T. Baumgartl.- Analytical evidence of shear band bifurcations for softening materials, by D. Caillerie, R. Chambon and F. Collin.- Shear banding in cross-anisotropic sand tests with stress rotation, by P. V. Lade.- Instability of Unsaturated Soil during the Water Infiltration, by F. Oka, E. Garcia and S. Kimoto .- A revisit to undrained shear banding in water-saturated s...