Quantification of non-coaxiality in constitutive relationship of clays and its application to limit equilibrium problem

近年来，岩土材料的局部化变形问题引起了众多学者的关注，他们期望能对地基的渐进破坏和承载力的尺寸效应等现象给出合理的解释。本文建立了饱和土体初边值问题的数学模型，并在适当的初边值条件下，用有限元法进行了求解。土骨架采用弹塑性剑桥模型。在这项研究中，土/水耦合问题的理论框架扩展到有限变形场的初始边值问题的解可能会发生分歧。提出了控制方程的离散化方法。在检验了有限元格式的数值稳定性后，对平面应变条件下的粘土试件进行了三轴压剪试验模拟。结果表明，作为应变局部化现象的剪切带总是伴随着剪胀而发展的，可以称之为剪胀局部化。此外，本研究还探讨了这种非线性土/水耦合公式在工程实践中的适用性。

Recently, localized deformation in geo-materials has attracted many researchers with expecting rational explanation of phenomena such as progressive failure and size effect of footing on bearing capacity. The mathematical formulation of initial-boundary value problem for saturated soil mass is presented and the finite element technique is applied to solve it under appropriate initial and boundary conditions. The elastoplastic Cam-clay model is employed for the soil skeleton. In this study the theoretical framework for the soil/water coupled problem is extended to the finite deformation field where bifurcation of solutions in an initial boundary value problem may occur. The discretization for governing equations is proposed. After examining the numerical stability of the finite element scheme, the triaxial compression shear test of a clay specimen is simulated under the plane strain condition. It is revealed that the shear band observed as the strain localization in clay specimen always develops with dilation, which can be called the localization of dilatancy. Moreover is examined the applicability of such non-linear soil/water coupled formulation in the engineering practice in this study.