Title:
Chemo-Mechanical Damage and Healing of Granular Salt: Micro-macro modeling
Chemo-Mechanical Damage and Healing of Granular Salt: Micro-macro modeling
Author(s)
Xianda, Shen
Zhu, Cheng
Arson, Chloé
Zhu, Cheng
Arson, Chloé
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Abstract
A micro-macro chemo-mechanical model of damage and healing is proposed to predict the evolution of salt stiffness
and deformation upon micro-crack propagation, opening, closure and rebonding, which is the result of pressure solution. We
hypothesize that at a given grain contact, the surface area of the contact dictates which mechanism dominates the rate of healing.
Based on thermodynamic equations of dissolution, diffusion and precipitation, we establish a formula for the critical contact area
that marks the transition between diffusion-dominated kinetics and dissolution-precipitation-dominated kinetics. We relate the
change of contact area to the change of solid volume in the Representative Elementary Volume, and we define net damage as the
sum of the mechanical damage and the chemical porosity change. A continuum-based damage mechanics framework is used to
deduce the change of salt stiffness with net damage. A stress path comprising a tensile loading, a compressive unloading, a creep–
healing stage and a reloading is simulated. Stiffness degradation and residual strain development are observed with the evolution of
damage under tensile loading. Unilateral effects of crack closure can be predicted by the model upon compression. Our micromacro
model also allows predicting the evolution of the probability distribution of contact areas upon healing, as well as the
consequent decrease of net damage and recovery of stiffness. The proposed modeling framework is expected to shed light on
coupled healing processes that govern microstructure changes and subsequent variations of deformation rate, stiffness and
permeability in salt rock, and to allow the assessment of long-term behavior of geological storage facilities in salt.
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Date Issued
2016-06
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