封闭块碎石层最佳降温粒径的室内试验研究

对不同粒径块碎石层在封闭条件下的降温效果进行了系列室内试验研究,试验中块碎石层厚度为1.3 m,采用的4种块碎石平均粒径分别为8.3 cm、14.8 cm、22.1 cm和27.1 cm.结果表明:在顶部温度(平均温度为正)周期波动条件下,4种粒径块碎石层均有一定的降温效果,但平均粒径为22.1 cm的块碎石层降温效果最好.经综合分析确定,封闭块碎石层在本试验条件下的最优降温粒径范围为20~30 cm.在全球升温与人类工程活动的背景下,即使路基表面平均温度升为正,只要合理利用块碎石层的降温特性,就可以达到有效保护其下部多年冻土的目的.

Laboratory Study of Particle Size for Optimal Cooling Effect of Closed Crushed-rock Layers

A series of Laboratory studies were carried out on the cooling effects of closed crushed rock layers,whose thickness was 1.3m and average particle sizes were 8.3,14.8,22.1 and 27.1 cm,respectively.The experimental results indicate that,when the temperature fluctuates periodically,the crushed-rock layers with different particle sizes all have a certain cooling effect;however,the cooling effect of the crushed rock mass of the mean particle size of 22.1 cm is the best among them.From synthetical analyses,it is found that the optimized particle size range with better cooling effect of the closed crushed-rock layer is 20～30 cm under the experimental condition in this paper.The research shows that under the global warming and engineering construction conditions,even if the mean temperature at the surface of an embankment is above 0℃,the underlying permafrost can be protected effectively as long as the “thermal diode” effect of the crushed-rock layer is utilized efficiently.