The interaction between rainfall and train vibration load is easy to cause uneven settlement of subgrade. Analyzing effects of different soaking processes on deformation characteristics of soil is beneficial to evaluate the ride comfort of subgrade after heavy haul train capacity expansion transformation. The dynamic tri-axis instrument was used to conduct tri-axis tests of different soaking processes to analyze effects of soaking process on wetting deformation,hysteretic curve and softening index. The results showed that soaking process significantly affects wetting deformation,and wetting deformation is larger,but it is faster to be stable after the capacity expansion of the soaking bed in the early stage,while the changing trend of wetting deformation is larger,but it is hard to reach a stable state after the capacity expansion of the unflooded bed in the early stage; the softening index drops faster and the soil softening tendency is larger after the capacity expansion of the unflooded bed in the early stage; the softening index quickly tends to be stable and the soil softening tendency is not obvious after the capacity expansion of the soaking bed in the early stage; under the same soaking process, wetting deformation increases with increase in axle load; when the axle load is more than 30 t,wetting deformation is a control factor to affect subgrade's ride comfort.%降雨与列车振动荷载相互作用易引起基床不均匀沉降,分析动力作用下不同浸水过程对土体变形特性的影响有利于评价重载列车扩能改造后基床的平顺性.利用动三轴仪,进行了不同浸水过程的动三轴试验,分析浸水过程对湿化变形、滞回曲线以及软化指数的影响.结果表明:浸水过程对于湿化变形有显著影响,前期浸水基床扩能改造后湿化变形较大但稳定较快,前期未浸水基床扩能改造后湿化变形趋势较大,不易达到稳定状态;前期未浸水基床在扩能改造后软化指数下降较快,土体软化趋势较大,浸水基床在扩能改造后软化指数很快趋于稳定,软化趋势不明显;在相同的浸水过程下,湿化变形随轴重的增加而增加,轴重在超过30 t后,湿化变形将是影响路基平顺性的控制因素.
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