In the late 1990s there has been a dramatic increase in the number of mathematical models developed to tackle geomechanics problems, largely as a result of the increasing availability and power of computers and the parallel evolution of versatile numerical techniques. This text examines the experimental and theoretical aspects of the pre-failure and post-failure behaviour of geomaterials within the frame of bifurcation theory. Coverage includes basic continuum mechanics for dry and fluid infiltrated porous media, bifurcation and stability analyses applied to layered geological media and granular materials, and theories for generalized continua (Cosserat and gradient theories) as applied to materials with microstructure and in relation to strain localization phenomena. This volume will be a source of reference for researchers and practitioners in soil and rock mechanics, and foundation engineering, and engineers, geologists and structural, civil and geotechincal engineers.