Study on shear strength property of re-slide type landslide and failure mechanism

为研究滑坡的特性，对粘性土进行了常偏应力作用下的孔隙水压力加载试验。通过对土样的观测，得到了土样变形的两个临界孔隙水压力值。一个是屈服点，另一个是失败点。通过与实验结果的比较，表明次加载面模式本构方程能够很好地表达这些阈值。通过数值模拟，研究了孔隙水压力重复加载的阈值大小的变化。针对孔压荷载的重复作用，绘制了破坏点的破坏预测线，表达了重复荷载作用下状态变量的变化过程。并通过实验对所得到的失效曲线进行了检验。证明了失效分界线的存在，但也观察到了模拟与实验之间的差异。有人指出， ...更多信息 l实验标本。试件中元素性质的损失是实验研究理想破坏应力的一个严重问题。详细的讨论留待以后再讨论.孔隙水压力作用下，土样的破坏过程是渐进的。从土力学的角度分析，滑坡的缓慢破坏是一种渐进性破坏。在实验中还测量了所谓的第二蠕变行为。这一现象可以从土水耦合的概念中得到解释。在孔隙水压力加载过程中，土体表现出两种相反的效应：一种是由于孔隙水压力的增加而产生的应变软化效应，另一种是由于孔隙水压力的减小而产生的固结效应。在反复荷载作用下，两种相反效应的平衡对粘土的强度影响很大。在本研究中，边坡稳定性的方法，包括预滑移线也发展。采用刚塑性本构方程。少

Pore water pressure loading test on clay under constant deviator stress was conducted to investigate the behavior of landslide. From the observation on soil specimen, two threshold magnitudes in pore water pressure for deformation were obtained. One was a yield point and the other was a failure point. It was shown that the constitutive equation of sub-loading surface mode could express these threshold magnitudes through the comparison with experiments. The change in threshold magnitudes for repeats of pore water pressure loading was investigated with simulation. The failure envelopment line was drawn for failure points against the repeats of pore water pressure loading, which expressed the change process of state variable for repeated loads. The obtained failure envelopment line was examined with experiments. The existence of failure envelopment line was proved, however, the discrepancy between simulation and experiment was observed. It was pointed out to the progressive failure of soi … More l specimen in experiment. The lost of element property in specimen was a serious problem to investigate the ideal failure stress in experiment. The detailed discussion was left to future problem. Time dependent behavior of soil specimen for pore water pressure loading was observed due to progressive failure. It suggested that the slow failure of landslide was due to progressive failure from the viewpoint of soil mechanics. The so-called second creep behavior was also measured in experiment. This phenomenon would be clarified from soil-water coupling concept. In pore water pressure loading cycle, two opposite effects were observed: one was a strain softening for increase in pore water pressure and the other was a consolidation for decrease in pore water pressure. The balance of two opposite effects much affected the soil strength of clay for repeated loads. In this study stability method for slope including the preformed slip line was also developed. Rigid plastic constitutive equation was employed. Less