青藏铁路管道通风试验路基地温变化及热状况分析

基于青藏铁路北麓河试验段管道通风路基在2个冻融循环周期内的地温监测资料，分析了路基温度的发展、温度场分布特征及多年冻土的热流量变化．结果表明：通风管埋设于路堤中部的路基温度变化和发展情况与一般路基类似，路基在施工后的2个冻融周期内仍处于整体升温的过程；通风管埋设于路堤下部的路基，虽然前2个冻融循环周期内土体温度与原始状态相比同样有所升高，但开始出现逐渐降低的趋势，同时地温场的分布在横向上的对称性也比较好，在热交换方面，一般填土路基和通风管位于路堤中部的路基在施工后的前2个冻融循环周期内一直处于吸热过程，而通风管位于路堤下部的路基在经历了第1个周期的持续吸热过程后，在第2个冻融循环周期内已经开始放热。

Analysis of Ground Temperature Change and Thermal Process in the Testing Duct-ventilated Embankment of the Qinghai-Tibet Railway

Ground temperature was monitored for two years in the Beiluhe Testing Section of the Qinghai-Tibet Railway, where a field-testing embankment was constructed and observed. Based on the monitoring, the ground temperature change, thermal regime and thermal process are discussed. It is found that the ground temperature change and thermal process of duct-ventilation embankment with ducts posited at half height of the embankment are similar to those of normal embankment. The temperature of the roadbed roundly increases during the first two freezing-thawing circles after the embankment complicated. Both of the normal embankment and the high-posited duct ventilation embankment are passive in protecting permafrost. However, the duct-ventilated embankment with deep-posited ducts shows a striking difference. The ground temperature of the roadbed soon decreases during the second freezing-thawing circle, though it increases during the first circle. The underlying permafrost begins emission after the first circle. Such process indicates that the ventilating ducts are active in cooling the underlying permafrost when they are laid deeply in the embankment.