多年冻土区铁路通风路基室内模型试验的温度场特征

Temperature Field Features in the Laboratory Experiment of the Ventilated Railway Embankment in Permafrost Regions

根据多年冻土区铁路通风结构路基室内模型试验的研究 ,分析了模型路基典型部位的温度随时间的变化情况 ,及整个路基 3个典型断面在冻结期结束和融化期结束时的温度场特征 .结果表明 :路基底部温度变化与气温变化趋势不一致 ;路基上部温度变化与气温变化趋势一致 ,但存在滞后现象 ;沿着风向方向 ,在冻结期 ,路基温度分布比较对称 ,但在融化期 ,就形成不对称分布 ;除了在通风管中部上方小部分有明显不同外 ,通过通风管中心轴断面的温度场特征与两通风管间断面的温度场分布特征在同一时刻是相似的 .

In this paper the laboratory experimental results of ventilated railway embankment in permafrost regions are presented. The model embankment is 1\^00 m high and 5\^13 m long at the bottom and 2\^13 m long at the top, and the slope is 1∶1\^5. The environmental temperature of the model embankment is changed according to a sine function \%T=-3\^5+12\%sin\%(2π15τ)\%, and the wind is about 3\^2 m\5s~ -1 at the inlet site of the ventilated duct and about 2\^37 m\5s~ -1 at the outlet. The test period is 15 days, including a freezing period of 8\^1 days and a thawing period of 6\^9 days. Three freezing\|thawing cycles are conducted. The filling of the embankment is sandy gravel.\;The temperature curves of some typical sites of the ventilated embankment are analyzed. The temperature fields of three typical sections (cross\|section, the symmetric axis section and section between two of the ventilated ducts) at two different moments (the end of the freezing period and the end of the thawing period) are analyzed too. Results show that at the bottom of the embankment temperature variation is not according to changing air temperature, but temperature near the embankment surface varies with air temperature. Along the wind direction, the distribution of temperature in the embankment is not symmetrical when the freezing period is over, but it is symmetrical when the thawing period is over. Temperature difference at different sites in the ventilated ducts is obvious during the temperature descending in the freezing period. The non\|symmetrical distribution of air temperature in the ventilated duct is accordance with the non\|symmetrical distribution of soil temperature of the embankment. The slope of the temperature curve is very small at the embankment bottom, where the temperature is close to 0 ℃.