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本文通过分析路基在冻结与融化时期水分场的变化规律,建立温度场与水分场的冻结融化模型试验,从而揭示路基病害的发生机理。对某冻土地区道路工程的研究结果表明:冻土路基温度场的季节活动深度为2~8m,路基深部土体的温度受外界温度的影响呈现滞后性;冻结与融化时期在路中以下2~4m深度范围内温度梯度较大;在路基融化时期的大气降水渗流过程中,路肩以下路基填土范围内的饱和度与地基的饱和度出现较大的差异,呈现出明显的分层现象;冻结时期土中未冻水向冻结锋面迁移导致路中以下2~3m深处含水率突增,冻结与融化时期路基总变形量较大。水热作用下路基产生的不均匀的冻胀与融沉变形是造成冻土路基病害的根本原因。
In this paper, by analyzing the variation law of the submerged ground during the freezing and thawing period, a freezing and thawing model test of the temperature field and the water field is established to reveal the mechanism of subgrade damage. The results of the study on road projects in a permafrost region show that the seasonal temperature of the temperature field in the frozen soil subgrade is 2 ~ 8m. The temperature of the soil in the subgrade is lagging behind by the external temperature. In the freezing and thawing period, In the process of atmospheric precipitation seepage during subgrade melting period, there is a big difference between the saturation in subgrade fill and subgrade under road shoulder, showing obvious stratification. During the freezing period, the unfrozen water in the soil migrates to the frozen front surface, causing the water cut in the depths of 2 ~ 3m below the road to suddenly increase. The total deformation of the roadbed during the freezing and thawing periods is larger. Under hydrothermal action, uneven frost heave and thaw settlement caused by subgrade are the basic causes of the damage of the permafrost embankment.