斜坡渗流对青藏公路多年冻土路基温度场的影响

Influence of Slope Seepage on Thermal Regime of Qinghai-Tibet Highway in Permafrost Regions

为了定量研究斜坡渗流对冻土区公路路基温度场的影响,建立了考虑相变和水分对流传热的冻土导热数值模型,对青藏公路斜坡路基温度场进行了数值模拟,研究了不同土质、不同斜坡坡度水分对流对冻土路基温度场的影响。结果表明:活动层水分渗流对冻土路基的影响主要表现为人为上限下降以及深部冻土的升温,水分渗流对路基下坡脚、路基中心的影响最为显著;浅地表导水系数越高、坡度越大,水分流动对温度场影响越大;对于浅层地表渗透性高(Ks>4×10-7 m·s-1)、含水量接近饱和且坡度较大(>10%)的斜坡路段路基,水分渗流对冻土路基稳定性影响不可忽略。

To examine the influence of water flow on permafrost thermal dynamics, a heat transport model with water flow is presented, in which water phase change and its effect on soil permeability are considered. A series of simulation models with and without water flow for different soil types and different slope gradient are conducted. The results show that effects of the seepage in active layer lowered the artificial permafrost table of sloping subgrade and warm the permafrost. The seepage has a significant effect on the thermal regime of slope toe and the center of embankment. The higher saturated hydraulic conductivity and slope gradient are, the greater effect of water flow on temperature field is. When the saturated hydraulic conductivity is high （Ks〉4×10-7 m·s-1 ） and slope gradient is large （〉10 %） in wetting slope embankment, the effect of sloping seepage on the thermal regime of sloping subgrade embankment temperature should not be neglected.