弹塑性多孔介质流固耦合新理论:混合耦合理论

New theory of Elasto-Plastic porous media Hydro-Mechanical coupling:Mixture Coupling Theory

在全球气候变化和双碳政策的大背景下,多孔介质中固体的变形和流体的输运问题变得尤为重要。然而,在多孔介质中建立流固耦合模型仍面临的挑战之一是需要考虑跨越宏观尺度到纳米尺度的耦合作用。本文利用基于非平衡热力学的混合耦合理论,提出了一个弹塑性多孔介质流固耦合新模型,在同一个理论框架内研究了弹性变形、塑性变形和液体渗流之间跨尺度的耦合,考虑了耗散过程中的熵产,并利用Helmholtz自由能连接宏观尺度上的力学变形和纳米尺度上的液体输运之间的相互作用。在应力-应变关系中采用了弹塑性刚度系数以反映塑性的影响。同时,经典的达西定律扩展为可考虑固体的塑性变形。通过与文献中模型的比较,验证了该模型的有效性。最后,数值分析表明在多孔介质的流固耦合中塑性变形具有比较显著的影响。

Due to global climate change and the Dual Carbon policy,the deformation of solids of and the transport of fluids in porous media have become particularly important issues.However,one of the challenges in establishing a Hydro-Mechanical coupling model for porous media is to consider interactions across macro-scale to nano-scale.This paper utilizes the Mixture Coupling Theory based on non-equilibrium thermodynamics to establish a new Hydro-Mechanical coupling model for elastic-plastic porous media.Within this framework,it investigates the coupling between elastic deformation,plastic deformation and liquid seepage,taking into account entropy production during dissipation process and using the Helmholtz free energy to connect the interaction between mechanical deformation(at the macroscopic scale)and liquid transport(at the nano-scale).The model incorporates elastic-plastic stiffness coefficients in the stress-strain relationship to account for plasticity.At the same time,the classical Darcy’s law has been fundamentally extended to consider the plastic deformation of the solid.The effectiveness of this model is verified by comparison with models in the open literature.Finally,numerical analysis shows that plastic deformation has a significant impact on HM coupling for porous media.