路基土体“锅盖效应”的数值模拟分析

Simulation and analysis of pot-cover effect on moisture transport in subgrade soil

基于对道面下路基土体中"锅盖效应"形成机制的定性认识,依据非饱和土中气液传输及热传导多场耦合理论并考虑水的气液相转换,建议了对此问题进行分析的数学模型。采用有限元方法对道面下路基一维土柱进行模拟分析,揭示了土中水和水蒸气在变温作用下的运移及相变规律,分析了"锅盖效应"形成条件和影响因素。数值结果显示,土质和温度分布对路基土发生"锅盖效应"有较大影响。粉土路基较黏土或砂土路基更易形成水分聚集;路基顶部温度较路基深处温度低时,在温度作用下易引起路基土的"锅盖效应"。这些结果可为进一步研究道路工程中的"锅盖效应"提供参考。

Based on qualitative understanding of the so-called pot-cover effect on moisture transport in the road subgrade soil, a mathematical model is proposed to analyze multi-phase transportation, heat conduction, and water-vapor transition. A one-dimensional finite element model for subgrade soil column is developed to investigate moisture transport and phase change under temperature gradient, as well as the mechanism and influencing factors Of pot-cover effect. The numerical results indicate that the temperature profile and soil texture may have significant influence on pot：cover effect. Pot-cover effect is more likely observed in silt subgrade than in sand or clay subgrade. The temperature profile of lower temperature at the top subgrade more easily leads to the pot-cover effect. These results provide reference for further understanding the pot-cover effect in subgrade soil.