EXPLICATION OF PROGRESS FAILURE IN SLOPE STABILITY AND ITS ANALYSIS WITH STRAIN-SOFTENING CONSTITUTIVE EQUATION

由软岩或超固结粘土组成的边坡破坏可以认为是渐进式破坏的结果，即局部破坏是由边坡内部某一局部点的应力非均匀分布引起的，并逐渐扩展到边坡的其他部位。首先，通过三轴试验等试验，研究了软岩和超固结粘土的时变特性以及物理化学裂隙特性对应变硬化-软化特性的影响。在试验结果的基础上，对首席研究员等人提出的硬化-软化型本构方程进行了扩展，使之能够同时描述边坡的时变行为和物理化学裂隙行为。第二步，将扩展后的本构方程应用于边坡破坏现象并建立其分析模型，讨论了边值问题。采用多种方法对边坡破坏模型进行了模拟，得到了描述渐进破坏现象的最佳模拟方法。第三步，利用离心机进行模型试验。在试验中，虽然在离心力场中尝试了开挖边坡和天然边坡的渐进性破坏现象，但直到现阶段才得到结论，并将继续进行研究，将研究成果不仅应用于边坡的合理设计、施工和维护，还将应用于边坡破坏的预测。

The slope failure, composed by the soft rock or over-consolidated clay, can be considered to be induced as the results of the progressive failure in which the local failure is generated by non-homogeneous distribution of stress at a local point inside the slope at the start, and it progressively propagates to other parts in the slope. We tried to obtain an analytical model with which the slope failure can be simulated as a progressive failure phenomenon.At the first step of the research, we investigated the time-dependent behavior of soft rock and over-consolidated clay and the effects of physicochemical fissure behavior to the strain-hardening-softening behavior through some experiments such as the triaxial tests. The hardening-softening type of the constitutive equation, which had been proposed by the head investigator, et al., was extended, on the base of the experimental results, to be able to express both the time-dependent behavior and the physicochemical fissure behavior.At the second step, the boundary value problem was discussed by applying the extended constitutive equation to the slope failure phenomenon and creating the analytical model for it. Some model cases of the slope failure were simulated by a few methods and the optimum simulating method was obtained to express the progressive failure phenomenon.At the third step, the model experiments were carried out by using centrifuge. In the experiments, though the progressive failure phenomenon of both the excavated and natural slope was tried to reproduce the progress failure in a centrifuge force field, the conclusive results have not been obtained yet until the current stage.The continuous research will be carried out to apply the results of the research not only to the rational design, construction and maintenance of slopes but also to the prediction of the slope failure.