Deformation and localization analysis of partially saturated soil
Deformation and localization analysis of partially saturated soil
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DOI：
10.1016/j.cma.2003.09.026
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发表时间：
2004-07
影响因子：
7.2
通讯作者：
W. Ehlers;T. Graf;M. Ammann
中科院分区：
文献类型：
--
作者：
W. Ehlers;T. Graf;M. Ammann
变形和局部化分析是一个至关重要的问题，因此在过去的几十年中得到了深入的研究。然而，与固体力学问题相比，岩土工程应用不仅涉及单一的固体材料，土壤，但它们也影响孔隙流体，水和空气，因此，固体变形与孔隙流体流动的耦合。因此，变形和局部化分析都必须应用于由土骨架、孔隙水和孔隙气体组成的三相材料，在岩土工程中称为非饱和土或部分饱和土。基于连续介质力学方法，非饱和土可以在多孔介质理论（TPM）的良好基础框架内描述，因此包括饱和土（固体基质和孔隙水）以及空土（固体基质和孔隙气体）作为特殊情况。本文的目的是研究非饱和土的变形和局部化行为，并揭示固流耦合对局部化分析的影响。在三相理论框架下，非饱和土被看作是一个被两种粘性孔隙流体饱和的不可压缩的弹塑性或弹粘塑性骨架，即不可压缩的孔隙流体和可压缩的孔隙气体。假设准静态的情况下，数值计算进行从整体三相材料的动量平衡与孔隙流体的质量平衡方程和达西的渗流速度的关系的弱配方。其结果是，一个系统的强耦合微分代数方程（DAE）的发生，这是通过使用有限元工具PANDAS解决。特别是，各种初始边值问题的时间和空间自适应方法的基础上处理，从而证明了整体制定的效率。此外，孔隙气体成分对部分饱和土的材料特性的影响进行了研究，相对于流体流动模拟或路堤和边坡破坏问题。
Deformation and localization analysis is a crucial issue and has thus been intensively investigated in the last decades. However, in contrast to solid mechanical problems, geotechnical applications do not only concern a single solid material, the soil, but they also affect the pore-fluids, water and air, and, consequently, the coupling of the solid deformation with the pore-fluid flow. As a result, both the deformation and the localization analysis must be applied to a triphasic material consisting of the soil skeleton, the pore-water and the pore-gas, which, in geotechnical engineering, is known as unsaturated or partially saturated soil. Based on a continuum mechanical approach, unsaturated soil can be described within the well-founded framework of the Theory of Porous Media (TPM), thus including saturated soil (solid matrix and pore-water) as well as empty soil (solid matrix and pore-gas) as special cases. It is the goal of the present contribution to investigate the deformation and the localization behavior of unsaturated soil and to exhibit the influence of the solid–fluid coupling on the localization analysis. In the framework of a triphasic formulation, unsaturated soil is considered as a materially incompressible elasto-plastic or elasto-viscoplastic skeleton saturated by two viscous pore-fluids, a materially incompressible pore-liquid and a materially compressible pore-gas. Assuming quasi-static situations, the numerical computations proceed from weak formulations of the momentum balance of the overall triphasic material together with the mass balance equations of the pore-fluids and Darcy-like relations for the seepage velocities. As a result, a system of strongly coupled differential-algebraic equations (DAE) occurs, which is solved by use of the FE tool PANDAS. In particular, various initial boundary-value problems are treated on the basis of time- and space-adaptive methods, thus demonstrating the efficiency of the overall formulation. Furthermore, the influence of the pore-gas constituent on the material behavior of partially saturated soil is studied with respect to fluid-flow simulations or embankment and slope failure problems.