This study is part of numerical simulations performed on an in-situ heating test conducted by the French National Radioactive Waste Management Agency (Andra) at the Meuse/Haute-Marne Underground Research Laboratory (URL) to study the hydromechanical behavior of the host Callovo-Oxfordian COx claystone in quasi real conditions through the international research project DECOVALEX. In this study, we present a numerical analysis of damage and cracking behavior due to gas effects on hydromechanical processes in unsaturated claystone, while considering the distribution of material heterogeneity. The proposed model is implemented in a finite element code designed to solve hydromechanical coupling problems under unsaturated conditions. The nucleation and propagation of cracks are described using an extended phase-field method, which takes into account the effects of gas and liquid pressure on the evolution of the phase-field. In particular, a macroscopic elastic model is determined using two steps of homogenization, which considers the effects of porosity and mineral inclusions. The spatial variability of these factors is modeled using the Weibull distribution function. Thus, the nucleation of cracks is directly influenced by the spatial distribution of material heterogeneity. The proposed model is applied to 3D benchmarks of gas injection in the context of radioactive waste disposal. The process, in which the overpressure-induced damage zone affects the behavior of the two-phase flow during gas injection, is well reproduced.

中文翻译：

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放射性废物处置背景下不饱和流体力学过程注气诱发裂纹的数值模拟

这项研究是法国国家放射性废物管理机构 (Andra) 在默兹/上马恩省地下研究实验室 (URL) 进行的原位加热测试数值模拟的一部分，旨在研究宿主 Callovo 的流体力学行为通过国际研究项目 DECOVALEX 获得准真实条件下的牛津 COx 粘土岩。在这项研究中，我们对非饱和粘土岩中气体对流体力学过程的影响造成的损伤和开裂行为进行了数值分析，同时考虑了材料非均质性的分布。所提出的模型在有限元代码中实现，该代码旨在解决非饱和条件下的流体力学耦合问题。使用扩展相场方法描述裂纹的成核和扩展，该方法考虑了气体和液体压力对相场演化的影响。特别是，宏观弹性模型是使用两步均质化确定的，其中考虑了孔隙度和矿物包裹体的影响。使用威布尔分布函数对这些因素的空间变异性进行建模。因此，裂纹的成核直接受到材料异质性的空间分布的影响。所提出的模型应用于放射性废物处理背景下气体注入的 3D 基准。过压引起的损伤区域影响注气过程中两相流行为的过程得到了很好的再现。