A thermomechanical damage approach to constitutive models for rate-independent dissipative geomaterials
This paper builds the formulations of hyperplastic damage theory for rate-independent geomaterials to describe the bulk and the likely damage behavior of granular materials. Using 2 kinematic internal variables and the conjugates, dissipative and yield function can be reasonably introduced. A systematic constitutive presentation of 32 possible ways within the thermodynamical damage framework is presented, which entirely formulates the constitutive behavior through two scalar thermodynamic potentials. Combining the four common thermodynamical energy functions, two independent kinematic internal variables and the accordingly generalized stress are introduced to describe the damage behavior and structural rearrangement of the granules for any bulk deformation. A few Legendre transformations are used to establish the links between energy functions so that the complex incremental response of geomaterials can be entirely established from these four energy functions. The constitutive relations are built with the thermodynamics laws, which account for the important structural aspects of geomaterials. Some examples are provided in the appendix to validate the applicability and implementation of the framework. This theory is based on previous work by Houlsby et al., and extends to the multi-mechanisms description. This framework paves a way in developing models for specific geomaterials with an examinable basis.
Key wordsthermomechanical damage approach hyperplastic energy dissipation
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