青藏铁路冻土区块石护坡路基热传递特性

块石护坡路基是青藏铁路建设中一种有效的冷却地基保护冻土工程措施.考虑高原夏季夜间冷空气对块石护坡路基温度场的影响,对青藏铁路北麓河块石护坡试验路基夏季某一整天的温度场、热流量和热流密度进行了分析,研究块石护坡路基昼夜间热传递特性.结果表明:块石护坡路基在夏季白天吸收热量,在夜间冷空气的作用下路基释放一部分热量,说明夏季夜间存在一定的降温效果.另外考虑一年内冷暖季块石护坡的热传递差异,对块石护坡路基冷暖季的温度场、热流量和热流密度变化情况进行研究,探讨其冷暖季热传递特性,结果显示:块石护坡路基暖季处于吸热状态,冷季处于放热状态;从一年的热流量变化看,块石护坡路基冷季的放热量大于吸热量,路基储存冷能有利于保护冻土.

Heat Transfer Characteristics of the Embankment with Crushed-Rock Slope Protection in Permafrost Regions along the Qinghai-Tibet Railway

The embankment with crushed-rock slope protection is a main measure for cooling the permafrost under the Qinghai-Tibet railway.Considering the nocturnal cooling effect on the Qinghai-Tibet railway embankment in summer,numerical analyses about the temperature field,heat flux and thermal flow of the railway embankment with crushed-rock slope protection were conducted.The results show the embankment absorbing heat during daytime and releasing some heat during nighttime under the influence of cool wind.These indicate that the embankment with crushed-rock slope protection has some cooling effect on permafrost during nighttime.In addition,considering the difference of the heat transfer during cold season and warm season,the year-round characteristics of heat transfer was studied.The results show that the embankment keeps in a status of absorbing heat during warm season and releasing heat during cold season.The annual released heat in cold reason is larger than the absorbed heat in warm season,which is helpful for protecting permafrost.