Genealogy of hypoplasticity and barodesy

This article is an attempt at providing an insight into the development of hypoplasticity (including barodesy, which is a recent development of hypoplasticity) as a theory elaborated since 1977, when the first version was published by the first author, until present. The multiplicity of the many versions published since then is hard to overlook. This article presents a review and insight into the evolution of a theory and the struggle to formulate a satisfactory constitutive law. Among the many proposed versions, we focus on those ones that can be seen as changes of paradigm. Copyright © 2016 John Wiley & Sons, Ltd.     

Sand eddies induced by cyclic tilt of a retaining wall

The cyclic tilt of a retaining wall induces a peculiar motion in the backfill (sand), which exhibits closed trajectories (eddies). In this paper, the motion of the backfill has been optically traced and analyzed by means of particle image velocimetry, also known as digital image correlation. The results are of importance for cyclically loaded structures (e.g, piles for off-shore structures) and can also serve to test numerical simulations of large deformation.     

Cavity expansion in cross‐anisotropic rock

Schistous rock can be considered—in a first approximation—as cross‐anisotropic linear elastic material. The determination of the corresponding material constants on the basis of the laboratory investigation of rock samples often fails, as the extraction of appropriate cores proves to be unfeasible (the cores disintegrate if the schistosity is pronounced). In this paper a new method is presented to determine the material constants of a linear elastic cross‐anisotropic rock on the basis of cavity expansion field tests, e.g. with a radial jack. To this purpose, an analytic approximation for the deformation of a hydrostatically loaded cylindrical cavity in cross‐anisotropic rock is derived which serves to the inverse analysis of the material parameters. Copyright © 2010 John Wiley & Sons, Ltd.     

Incompatible deformation in rock mechanics

Compatibility, i.e., continuous displacement field, is often taken for granted but experience teaches that rock deformation is in most cases discontinuous. The relation between incompatible deformation and continuous distribution of dislocations is established since long and is recalled in this paper. Contrary to several applications of Cosserat theory to already laminated (jointed) rock, the main goal of this paper is to give an explanation for the formation of discontinuities (joints) in rock as a result of a particular type of buckling which leads the body outside of the Euclidean space of its original configuration.     

Computer-aided design of constitutive laws

In this paper a method is presented which helps to develop and to check constitutive laws by means of computer experiments. The exposition has been carried out along the formalism of hypoplasticity, which has been introduced as a generalization of hypoelasticity. Several results of computer experiments are graphically represented.     

Proportional stress and strain paths in barodesy

Asymptotic behaviour of soil deserves particular attention: If soil is deformed with a proportional strain path, the resulting stress path approaches asymptotically a proportional stress path. In this arcticle, we review existing experimental evidence on this phenomenon and discuss it in the frame of barodesy. Here, the presented relation is a modification of a barodetic expression and includes Jáky's relation, inhibits tensile stress and is able to predict asymptotic stress ratios based on experimental findings. The proposed relation is compared with experimental data as well as with the so‐called stress‐dilatancy relations and other constitutive relations proposed so far. Copyright © 2015 John Wiley & Sons, Ltd.     

Barodesy: a new hypoplastic approach

It is shown that the asymptotic mechanical behaviour (i.e. stresses asymptotically obtained with constant deformation rates) determines the entire mechanical behaviour of granular materials, such as soil. In this paper, a constitutive model, or rather a new theoretical framework, for sand is derived in terms of rational mechanics. The new theory, called ‘barodesy’, has an outstanding simplicity and comprises previously introduced concepts of Soil Mechanics: critical states and barotropy (i.e. power law dependence of stiffness on stress). Copyright © 2011 John Wiley & Sons, Ltd.