AI 中文总结
本研究针对孔隙弹塑性介质的相场模型，通过修正流动法则与自由能耦合项，提升了流固耦合响应精度，可再现两类典型断裂模式。
AI 中文摘要
即使在以拉伸为主的裂纹扩展过程中，多孔材料也可能在扩展裂纹附近发生塑性变形，这是多孔材料的常见特性。现有相场模型通常采用非关联塑性流动法则，以及基于应变和流体压力的亥姆霍兹自由能。本研究通过分析强度面和裂纹驱动力，重新审视了孔隙弹塑性介质断裂相场模型的流固耦合力学公式。分析表明，这类常用的流动法则和自由能选择会在拉压过渡处导致强度面不连续：非关联流动法则会在强度面处引入跳跃，而将流体压力（而非流体含量）作为亥姆霍兹自由能的自变量则会忽略相场驱动力中的耦合项，同样破坏连续性。引入关联Drucker-Prager流动法则和该遗漏的耦合项，可确保强度面连续且裂纹驱动力准确。与Kristianovich-Geertsma-de Klerk水力压裂基准的解析解相比，所提模型的流固耦合响应精度有所提升；对孔隙弹塑性介质的水力压裂和双轴压缩的数值模拟显示，该模型可再现机械扰动诱发的剪切主导型断裂，以及饱和多孔介质中流体注入驱动的拉伸主导型断裂。
英文摘要
Even for tension-dominated fracture propagation, porous materials may deform plastically adjacent to the propagating fracture. As is common for porous materials, existing phase-field models typically employ a non-associative flow rule for plasticity, and a Helmholtz free energy based on strain and fluid pressure. This work revisits the hydromechanically coupled formulation of the phase-field model for fracture in poro-elastoplastic media by analyzing the strength surface and fracture driving force. Our analyses show that these common choices of flow rule and free energy will lead to a discontinuous strength surface across the tension-compression transition. A non-associative flow rule introduces a jump at the strength surface, while treating fluid pressure-rather than fluid content-as the independent variable in the Helmholtz free energy omits a coupling term from the phase-field driving force, also breaking continuity. Incorporating an associative Drucker-Prager flow rule and this omitted coupling term ensures a continuous strength surface and the accurate fracture driving force. The proposed model exhibits improved accuracy in hydromechanical responses when compared against the analytical solution of the Kristianovich-Geertsma-de Klerk hydraulic fracturing benchmark. Numerical simulations of hydraulic fracturing and biaxial compression in poro-elastoplastic media show that the model can reproduce both shear-dominated fractures induced by mechanical disturbance and tension-dominated fractures driven by fluid injection in saturated porous media.
Comments34 pages, 14 figures
