Constitutive Model for Multi-laminate Induced Anisotropic Double Hardening Elastic-plasticity of Sand

A constitutive multi-laminate based elastic-plastic model developed to be capable of accounting induced anisotropic behavior of granular material such as sand. The fabric feature or grain orientation characteristic effects through medium are considered in a rational way under any complex stress path, including cyclic loading. The salient feature of the developed model is a non-associative on plane plasticity with biaxial hardening as a function of plastic shear strain components. Generalized form of multi-laminate framework employed to sum up the non-symmetric plastic compliance matrices of sampling planes to build up the main compliance matrix. Two normal translation rules of yield boundary are specified upon the components of plastic shear strain on every sampling plane. The constitutive model is capable of describing expansion of two yield functions upon two predefined coordinate axes. The hardening parameters affect the plastic strain tensor uponthe contribution of twenty-six different sliding orientations through any point in medium. This contribution makes a powerful representation of strain hardening due to fabric effects in behavior of material. The comparison of experimental test results with model results represents that this model is more capable in cyclic behavior of porous media such as sand.