Dynamic crack branching in unsaturated porous media holds significant relevance in various fields, including geotechnical engineering, geosciences, and petroleum engineering. This article presents a numerical investigation into dynamic crack branching in unsaturated porous media using a recently developed coupled micro-periporomechanics paradigm. This paradigm extends the periporomechanics model by incorporating the micro-rotation of the solid skeleton. Within this framework, each material point is equipped with three degrees of freedom: displacement, micro-rotation, and fluid pressure. Consistent with the Cosserat continuum theory, a length scale associated with the micro-rotation of material points is inherently integrated into the model. This study encompasses several key aspects: (1) Validation of the coupled micro-periporomechanics paradigm for effectively modeling crack branching in deformable porous media, (2) Examination of the transition from a single branch to multiple branches in porous media under drained conditions, (3) Simulation of single crack branching in unsaturated porous media under dynamic loading conditions, and (4) Investigation of multiple crack branching in unsaturated porous media under dynamic loading conditions. The numerical results obtained in this study are systematically analyzed to elucidate the factors that influence dynamic crack branching in porous media subjected to dynamic loading. Furthermore, the comprehensive numerical findings underscore the efficacy and robustness of the coupled micro-periporomechanics paradigm in accurately modeling dynamic crack branching in variably saturated porous media.

翻译：非饱和多孔介质中的动态裂纹分叉在岩土工程、地球科学和石油工程等多个领域具有重要意义。本文利用最新发展的耦合微孔周力学范式，对非饱和多孔介质中的动态裂纹分叉进行了数值研究。该范式通过考虑固体骨架的微旋转，扩展了孔周力学模型。在此框架下，每个材料点具有三个自由度：位移、微旋转和流体压力。与Cosserat连续介质理论一致，与材料点微旋转相关的长度尺度被自然地集成到模型中。本研究涵盖以下几个关键方面：（1）验证耦合微孔周力学范式在可变形多孔介质中有效模拟裂纹分叉的能力；（2）研究排水条件下多孔介质中单一分叉向多分叉的转变；（3）模拟动态加载条件下非饱和多孔介质中的单一裂纹分叉；（4）探究动态加载条件下非饱和多孔介质中的多裂纹分叉。本文系统分析了数值结果，以阐明影响动态加载多孔介质中裂纹分叉的因素。此外，全面的数值结果突显了耦合微孔周力学范式在准确模拟变饱和多孔介质中动态裂纹分叉方面的有效性和鲁棒性。