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管道通风路基在多年冻土地区是一种良好的主动保护冻土工程措施,但在应用数值方法研究其长期效果中,对边界条件的选取存在着困难,已有的计算结果也缺乏实体工程的验证.基于青藏铁路北麓河实体试验工程,对通风管中气温以及管壁温度进行了分析和拟合.结果表明:通风管中气温年平均值普遍高于环境气温,平均高出1.6~1.8℃,但在正温期管中气温与环境气温的最高值相差不大(<1℃),而负温期相差较大(达到2℃);路基阳坡面下0.5 m深度地温高于阴坡面3.5~5.5℃.普通路基填筑后在抬升多年上限的同时,也升高了上限附近的地温,且地温场在整个范围内表现出横向上显著的不对称性.通风路基可以对下伏多年冻土起到良好的主动保护作用,表现为冻土上限的抬升和地温的降低.但通风管埋设位置较高的情况下,路基地温场横向不对称范围涉及到原地面以下.降低通风管的埋设高度的情况下,边坡面换热导致的温度横向不对称范围被限制在通风管以上的土体中,而下部土体温度场横向不对称性将得到极大改善.
In the permafrost region, pipeline ventilation subgrade is a good measure to proactively protect permafrost. However, it is difficult to select the boundary conditions by applying numerical method to study its long-term effect. The existing calculation results are also lack of physical engineering The results show that the average temperature of the air in the ventilation pipe is generally higher than the ambient air temperature and the average is 1.6-1.8 ℃, but the difference between the maximum temperature and the ambient air temperature in the positive temperature period is less (<1 ℃), while that in the negative temperature period is larger (up to 2 ℃) The slope surface is 3.5-5.5 ℃ .At the same time when the embankment is lifted, the ground temperature near the upper limit also increases, and the ground temperature field shows significant lateral asymmetry in the whole range. The volcanic permafrost plays an active protective role, which is manifested by the uplift of the upper limit of permafrost and the decrease of the ground temperature.When the position of the ventilation pipe is high, the lateral asymmetry of the ground temperature field is below the original ground surface. Ventilation duct The height of the case is buried, the surface temperature of the heat transfer due to lateral slope range is restricted asymmetric vent tube above the soil, and the soil temperature under a transverse field asymmetry will be greatly improved.