The present study evaluates the effect of stress history and loading conditions on dynamic behavior and failure characteristics of low plasticity cohesive soil. A series of two-way strain controlled cyclic triaxial tests were performed on soil samples collected from seismically active region of Gujarat (India). The effect of stress history and loading conditions on low plasticity soil was evaluated for OCR values of 1–4 and cyclic axial strain amplitude ( $$\varepsilon_{{\text{a}}}$$ ε a ) variation of 0.5%, 1%, 1.5%, and 2%, respectively. The low plasticity soil was observed to undergo liquefaction even at lower amplitude and higher OCR. Liquefaction resistance of soil was observed to increase with the increasing OCR (1–4) and decrease with the increment in cyclic strain amplitude (0.5%—2.0%). The rate of stiffness degradation exhibited bilinear response when pore pressure ratio ( r u ) was observed to be 0.85. This indicated the generation of cyclic instability prior to flow liquefaction in low plasticity cohesive soil. Two-staged failure response was observed due to the subsequent transition from cyclic instability behavior to flow liquefaction. The low plasticity cohesive soil was found to experience first ‘clay-like behaviour’ due to commencement of cyclic instability and then ‘sand-like behaviour’ due to initiation of flow liquefaction. The low plasticity cohesive soil was observed to experience cyclic instability between 0.85 < r u < 0.95, and then, flow liquefaction at r u > 0.95.

中文翻译：

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低塑性粘性土的动力行为及破坏特征响应

本研究评估应力历史和加载条件对低塑性粘性土的动力行为和破坏特征的影响。对从古吉拉特邦（印度）地震活跃地区采集的土壤样品进行了一系列双向应变控制循环三轴试验。应力历史和加载条件对低塑性土壤的影响被评估为 1-4 的 OCR 值和循环轴向应变幅度 ($$\varepsilon_{{\text{a}}}$$ ε a ) 变化为 0.5%，分别为 1%、1.5% 和 2%。观察到即使在较低振幅和较高 OCR 下，低塑性土壤也会发生液化。观察到土壤的液化阻力随着 OCR 的增加（1-4）而增加，并随着循环应变幅度的增加（0.5%-2.0%）而降低。当观察到孔隙压力比 (ru) 为 0.85 时，刚度退化率表现出双线性响应。这表明在低塑性粘性土中流动液化之前产生了循环不稳定性。由于随后从循环不稳定行为转变为流动液化，观察到两阶段失效响应。由于循环不稳定的开始，低塑性粘性土首先经历“粘土状行为”，然后由于流动液化的开始而经历“沙状行为”。观察到低塑性粘性土在 0.85 < ru < 0.95 之间经历循环不稳定，然后在 ru > 0.95 处流动液化。这表明在低塑性粘性土中流动液化之前产生了循环不稳定性。由于随后从循环不稳定行为转变为流动液化，观察到两阶段失效响应。由于循环不稳定的开始，低塑性粘性土首先经历“粘土状行为”，然后由于流动液化的开始而经历“沙状行为”。观察到低塑性粘性土在 0.85 < ru < 0.95 之间经历循环不稳定，然后在 ru > 0.95 处流动液化。这表明在低塑性粘性土中流动液化之前产生了循环不稳定性。由于随后从循环不稳定行为转变为流动液化，观察到两阶段失效响应。由于循环不稳定的开始，低塑性粘性土首先经历“粘土状行为”，然后由于流动液化的开始而经历“沙状行为”。观察到低塑性粘性土在 0.85 < ru < 0.95 之间经历循环不稳定，然后在 ru > 0.95 处流动液化。由于循环不稳定的开始，低塑性粘性土首先经历“粘土状行为”，然后由于流动液化的开始而经历“沙状行为”。观察到低塑性粘性土在 0.85 < ru < 0.95 之间经历循环不稳定，然后在 ru > 0.95 处流动液化。由于循环不稳定的开始，低塑性粘性土首先经历“粘土状行为”，然后由于流动液化的开始而经历“沙状行为”。观察到低塑性粘性土在 0.85 < ru < 0.95 之间经历循环不稳定，然后在 ru > 0.95 处流动液化。