The dependence of rock behavior on the deformation rate is still not well understood. In salt rock, the fundamental mechanisms that drive the accumulation of irreversible deformation, the reduction of stiffness, and the development of hysteresis during cyclic loading are usually attributed to intracrystalline plasticity and diffusion. We hypothesize that at low pressure and low temperature, the rate‐dependent behavior of salt rock is governed by water‐assisted diffusion along grain boundaries. Accordingly, a chemo‐mechanical homogenization framework is proposed in which the representative elementary volume (REV) is viewed as a homogeneous polycrystalline matrix that contains sliding grain‐boundary cracks. The slip is related to the mass of salt ions that diffuse along the crack surface. The relationship between fluid inclusion‐scale and REV‐scale stresses and strains is established by using the Mori–Tanaka homogenization scheme. It is noted from the model that a lower strain rate and a larger number of sliding cracks enhance stiffness reduction and hysteresis. Thinner sliding cracks (i.e., thinner brine films) promote stiffness reduction and accelerate stress redistributions. The larger the volume fraction of the crack inclusions, the larger the REV deformation and the larger the hysteresis. Results presented in this study shed light on the mechanical behavior of salt rock that is pertinent to the design of geological storage facilities that undergo cyclic unloading, which could help optimize the energy production cycle with low carbon emissions.

中文翻译：

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循环荷载作用下盐岩速率相关行为的微力学建模

岩石行为对变形率的依赖性还没有很好地理解。在盐岩中，驱动不可逆形变累积，降低刚度以及在循环加载过程中产生迟滞的基本机制通常归因于晶体内的可塑性和扩散。我们假设，在低压和低温下，盐岩的速率依赖性行为受水辅助沿晶界扩散的支配。因此，提出了一种化学机械均质化框架，在该框架中，代表性的基本体积（REV）被视为包含滑动晶界裂纹的均质多晶基体。滑移与沿裂纹表面扩散的盐离子质量有关。流体包裹体尺度与REV尺度应力和应变之间的关系是通过使用Mori–Tanaka均质化方案建立的。从模型中可以看出，较低的应变速率和较大数量的滑动裂纹会增加刚度降低和滞后现象。较薄的滑动裂纹（即较薄的盐水膜）促进刚度降低并加速应力重新分布。裂纹夹杂物的体积分数越大，REV变形越大，磁滞也越大。这项研究提出的结果揭示了盐岩的力学行为，这与经历周期性卸载的地质存储设施的设计有关，这可以帮助优化低碳排放的能源生产周期。从模型中可以看出，较低的应变速率和较大数量的滑动裂纹会增加刚度降低和滞后现象。较薄的滑动裂纹（即较薄的盐水膜）促进刚度降低并加速应力重新分布。裂纹夹杂物的体积分数越大，REV变形越大，磁滞也越大。这项研究提出的结果揭示了盐岩的力学行为，这与经历周期性卸载的地质存储设施的设计有关，这可以帮助优化低碳排放的能源生产周期。从模型中可以看出，较低的应变速率和较大数量的滑动裂纹会增加刚度降低和滞后现象。较薄的滑动裂纹（即较薄的盐水膜）促进刚度降低并加速应力重新分布。裂纹夹杂物的体积分数越大，REV变形越大，磁滞也越大。这项研究提出的结果揭示了盐岩的力学行为，这与经历周期性卸载的地质存储设施的设计有关，这可以帮助优化低碳排放的能源生产周期。较薄的盐水膜）有助于降低刚度并加速应力重新分布。裂纹夹杂物的体积分数越大，REV变形越大，磁滞也越大。这项研究提出的结果揭示了盐岩的力学行为，这与经历周期性卸载的地质存储设施的设计有关，这可以帮助优化低碳排放的能源生产周期。较薄的盐水膜）有助于降低刚度并加速应力重新分布。裂纹夹杂物的体积分数越大，REV变形越大，磁滞也越大。这项研究提出的结果揭示了盐岩的力学行为，这与经历周期性卸载的地质存储设施的设计有关，这可以帮助优化低碳排放的能源生产周期。