由于径向向外的流体注入而产生的大孔隙弹性塑性形变
Large poroelasto-plastic deformations due to radially outward fluid injection
摘要：
颗粒材料的流动诱导破坏与广泛的地质力学应用有关。塑性是大多数粒状材料的固有失效机制，它使大的变形能够使线性模型失效。受井眼流体注入的影响，建立了厚壁、部分渗透、弹性-理想塑性带压环空大变形的稳态模型。我们占预先存在的压缩应力，将存在于地下，通过从我们的解决方案中减去压缩的初始状态，以提供额外的干扰，由于流体注入。我们还引入了一个简单的参数，允许从不可渗透材料（即，在内壁处受到机械载荷）到完全可渗透的材料（即，受到内部孔隙压力梯度的影响），这与涂层钻孔和渗透率极低的材料有关。我们专注于多孔弹性和多孔弹性塑性形变之间的差异，运动学和本构非线性的作用，以及从不可渗透到完全渗透的过渡。我们发现，塑性可以使更大的变形，而预测小得多的应力。前者使得模型选择在塑性区变得越来越重要，而弹性区对这些变化保持不敏感。我们还发现，对于一个固定的总应力在内壁，材料经历更大的变形和一般更大的应力，因为它们从不可渗透的过渡到完全渗透。
英文摘要：
Flow-induced failure of granular materials is relevant to a broad range of geomechanical applications. Plasticity, which is the inherent failure mechanism of most granular materials, enables large deformations that can invalidate linearised models. Motivated by fluid injection into a borehole, we develop a steady-state model for the large deformation of a thick-walled, partially-permeable, elastic--perfectly-plastic annulus with a pressurised inner cavity. We account for pre-existing compressive stresses, as would be present in the subsurface, by subtracting a compressed initial state from our solutions to provide the additional disturbance due to fluid injection. We also introduce a simple parameter that allows for a smooth transition from an impermeable material (i.e., subject to mechanical loading at the inner wall) to a fully permeable material (i.e., subject to an internal pore-pressure gradient), which would be relevant to coated boreholes and very-low-permeability materials. We focus on the difference between poroelastic and poroelasto-plastic deformations, the role of kinematic and constitutive nonlinearity, and the transition from impermeable to fully permeable. We find that plasticity can enable much larger deformations while predicting much smaller stresses. The former makes model choice increasingly important in the plastic region, while the elastic region remains insensitive to these changes. We also find that, for a fixed total stress at the inner wall, materials experience larger deformations and generally larger stresses as they transition from impermeable to fully permeable.
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