Establishment of strain softening elasto-visco-plastic constitutive model and studies on the progressive failure of ground material

通过离心机模型试验和有限元分析，建立既能反映软岩和超固结粘土的应变软化行为又能反映时间相关性的本构模型，探讨由软岩和/或超固结粘土组成的边坡的稳定性，从而掌握渐进破坏的机理。此外，认为软岩的时变特性等同于有效应力随孔压的变化，将本构模型作为水耦合问题应用于边值问题。软岩和超固结粘土的显著力学行为表现为应力-应变关系中的应变硬化和软化，以及随应变软化而发生的正膨胀。在这个Re…中在此基础上，建立了以应力历史张量为屈服函数的应变软化弹塑性本构模型。在离心机模型试验中，模型地基为石膏-Fukakusa粘土混合地基。通过安装在模型地面上的目标的移动，观察和估计位移矢量和应变矢量，讨论边坡渐进破坏的机理，通过单元试验确定所提出的本构模型的各种参数，然后进行有限元土-水耦合分析来模拟边坡渐进破坏。最后，基于考虑应变软化的弹塑性本构模型，采用土-水耦合分析方法，对沉积泥岩路堑边坡的实际渐进破坏进行了模拟。将实际倒塌情况与数值计算结果进行对比，讨论了该模型的有效性和存在的问题。较少

By the centrifuge modeling tests and the finite element analyses, the purposes of this research work are to establish the constitutive model which can expresses both strain-softening and time dependency behavior of soft rock and over-consolidated clay, to discuss the stability of the slope which consists of soft rock and/or over-consolidated clay, and then to grasp the mechanism of the progressive failure. Moreover, it is considered that the time dependency behavior of soft rock is equivalent to the change of the effective stress with the change of pore pressure, the constitutive model is applied to the boundary value problem as the water-coupling problem. Then, the constitutive model with soil-water coupling is also applied to the collapse of the slope.The remarkable mechanical behavior of soft rock and over-consolidated clay can be presented by the strain hardening and softening in the stress - strain relation and the positive dilation with progressed the strain softening. In this re … More search work, the elasto-plastic constitutive model with strain softening whose yielding function is defined by the stress-history tensor are established.In the centrifuge modeling tests, the modeling ground makes of mixed Gypsum to Fukakusa clay. Displacement vectors and strain vectors are observed and estimated through the movement of the targets installed in the modeling ground, and then the mechanism of the progressive failure of the slope is discussed.Various parameters of the proposed constitutive model are determined through the element experiments, and then the finite element soil-water coupling analyses are carried out to simulate the progressive failure of the slope. As compared the numerical simulations with the experimental results, the progressive failure of the slope is discussed.Finally, actual progressive failure of cutting slope in the sedimentary mudstone is simulated by the soil-water coupled analysis based on the elasto-plastic constitutive model with strain softening. Compared the actual collapse with the numerical results, the validity and the problem of the proposed model are discussed. Less