Soil is a matter of its own right, whose properties should be modeled as accurately and reliably as possible. Geoscientists and geotechnical engineers rely on models to describe the properties of soil for engineering purposes. Soils are complex in composition, state and behaviour. This complexity can be mastered using state limits and limit cycles. The author presents constitutive concepts of elastoplasticity and hypoplasticity. The first part of this book deals with constitutive relations. For sand-like soils (psammoids), state limits are introduced, described as attractors, constitutive relations represented by means of related strain and state paths, validated by means of oedeometer, triaxial, cuboidal, simple shear and torsion shear results. The second part deals with boundary value problems for soils which are no more homogeneous with respect to state and composition. The concept of related evolutions of state and shape works throughout more complex boundary value problems.
