Evolution of anisotropy with saturation and its implications for the elastoplastic responses of clay rocks
Evolution of anisotropy with saturation and its implications for the elastoplastic responses of clay rocks
复制标题
各向异性随饱和度的演化及其对粘土岩弹塑性响应的影响
DOI：
10.1002/nag.3289
复制
发表时间：
2021-11
影响因子：
4
通讯作者：
S. C. Ip;R. Borja
中科院分区：
文献类型：
--
作者：
S. C. Ip;R. Borja
许多粘土岩有明显的层面。实验研究表明，它们的机械性能随着饱和度（DOS）的变化而变化，干燥后通常具有更高的刚度和强度。对于横观各向同性岩石，饱和度的影响在垂直于岩层（BN）和平行于岩层（BP）的方向上可能不同，这会导致饱和度相关的刚度和强度各向异性。准确预测部分饱和条件下粘土岩石的力学行为需要能够捕捉到随DOS变化的弹性和塑性各向异性的数值模型。在这项研究中，我们提出了一个各向异性框架耦合固体变形-流体流动在非饱和弹塑性介质。我们将饱和度相关的强度各向异性纳入各向异性修正的Cam‐Clay（MCC）模型，并考虑弹性和塑性响应中的各向异性。该模型进行了校准，从三轴试验的实验数据，以证明其在捕获强度各向异性在不同的饱和度水平的能力。通过数值模拟，我们展示了不断变化的刚度和强度各向异性的粘土岩石的力学行为中的作用。平面应变模拟的三轴压缩试验也进行了演示材料的各向异性和DOS的力学和流体流动响应的影响。
Many clay rocks have distinct bedding planes. Experimental studies have shown that their mechanical properties evolve with the degree of saturation (DOS), often with higher stiffness and strength after drying. For transversely isotropic rocks, the effects of saturation can differ between the bed‐normal (BN) and bed‐parallel (BP) directions, which gives rise to saturation‐dependent stiffness and strength anisotropy. Accurate prediction of the mechanical behavior of clay rocks under partially saturated conditions requires numerical models that can capture the evolving elastic and plastic anisotropy with DOS. In this study, we present an anisotropy framework for coupled solid deformation‐fluid flow in unsaturated elastoplastic media. We incorporate saturation‐dependent strength anisotropy into an anisotropic modified Cam‐Clay (MCC) model and consider the evolving anisotropy in both the elastic and plastic responses. The model was calibrated using experimental data from triaxial tests to demonstrate its capability in capturing strength anisotropy at various levels of saturation. Through numerical simulations, we demonstrate the role of evolving stiffness and strength anisotropy in the mechanical behavior of clay rocks. Plane strain simulations of triaxial compression tests were also conducted to demonstrate the impacts of material anisotropy and DOS on the mechanical and fluid flow responses.