Rail transport industry often desires to increase the freight capacities for heavy-haul trains to transport more goods. However, this requires an increase in the axle loads, which results in the railway foundation being subjected to higher cyclic stress ratio (CSR), causing significant subgrade distress. Recent laboratory investigations indicate that addition of kaolin to low-to-medium plasticity soils can avert early softening and fluidization of the soil under increasing CSR, how the dynamic parameters such as the shear modulus (G) and the damping ratio (D_p) of soils may change consequentially to this modification needs appropriate quantification. Furthermore, while there are plenty of studies correlating shear strain and plasticity index (PI) with the dynamic properties of the soil, the role of loading parameters such as the CSR and number of cycles (N) has not been thoroughly investigated. Therefore, efforts have been made to characterise the dynamic parameters of moderately plastic silty-clay soils with varying kaolin content (c_K) and loading parameters. The results indicate that as CSR exceeds a critical level, G decreases rapidly whereas D_p was found to increase abruptly in few loading cycles. The paper also shows that when G diminishes about 20% from its initial value, any further loss in shear modulus would cause soil to turn into an unstable stage where the excess pore water pressure and shear strain begins to increase rapidly. Although varying the kaolin content does not alter the PI significantly, it causes a considerable effect on the dynamic parameters of the soil. Based on the current experimental findings, empirical models are proposed to estimate dynamic parameters of subgrade soils prone to mud pumping considering loading condition under heavy haul railways.

铁路运输行业通常希望增加重型火车的货运能力，以运输更多的货物。然而，这需要增加轴载荷，这导致铁路地基承受较高的循环应力比（CSR），从而导致严重的路基遇险。最近的实验室研究表明，在高CSR的情况下，向中低塑性土壤中添加高岭土可以避免土壤的早期软化和流态化，以及诸如剪切模量（G）和阻尼比（D _p）等动态参数的作用。）的土壤可能会随之改变，因此需要适当的量化。此外，尽管有大量的研究将剪切应变和塑性指数（PI）与土壤的动力特性相关联，但尚未全面研究诸如CSR和循环次数（N）之类的载荷参数的作用。因此，已努力表征具有变化的高岭土含量（c _K）和荷载参数的中等塑性粉质粘土的动力参数。结果表明，随着CSR超过临界水平，G迅速降低，而D _p被发现在几个加载周期中突然增加。该论文还表明，当G从其初始值减小约20％时，剪切模量的任何进一步损失都将导致土壤进入不稳定阶段，在该阶段中，多余的孔隙水压力和剪切应变开始迅速增加。尽管改变高岭土含量不会显着改变PI，但会对土壤的动力学参数产生相当大的影响。基于目前的实验结果，提出了在重载铁路下考虑荷载条件下易于抽泥的路基土壤动力参数的经验模型。