青藏铁路多年冻土区热棒路基的冷却效果三维有限元分析

3-D finite element analysis of cooling effect of Qinghai-Tibet Railway embankment with thermosyphons in permafrost regions

为研究热棒对多年冻土区路基的冷却效果,根据青藏铁路试验段的路基设计资料及青藏高原的气候条件,分别对热棒间距为3,4,5和6 m的热棒路基进行了三维数值计算。根据计算结果,对以上4种条件下的热棒路基地温场分别在竣工后第1年、第10年和第30年的10月份沿路基横向和纵向的分布规律行了对比分析,并对在气候升温条件下的地温场发展趋势进行了预测,在以上分析基础上研究了间距4 m的热棒对路基的有效冷却范围。结果表明,热棒对路基有明显的降温作用,且在长期运营中热棒可以保证路基的稳定;随着热棒间距的增大,热棒对周围土体的整体冷却效果逐渐减弱,对于青藏高原试验段中的地质气候条件和热棒类型,其有效冷却半径约为2.0 m左右,热棒之间合理间距不应超过4.0 m。

To study the cooling effect of the embankment with thermosyphons, based on the design data of Anduo trial sector of Qinghai-Tibet Railway embankment and the climate data of Tibetan Plateau, three-dimensional finite element analysis is conducted to simulate the influence of different spacings of thermosyphons in the following 30 years. The spacings of thermosyphons used in the calculation are 3, 4, 5 and 6 m respectively, and the diameter of the thermosyphons is 89 mm. According to the calculated results, the horizontal and vertical distributions of temperature fields of the embankment are discussed on October 1st after 1 year, 10 years and 30 years of its construction respectively, and the development of temperature fields is predicted under the global climate warming. Finally, the cooling effects of the thermosyphons are analyzed when their spacing is 4 m. The results indicate that the thermosyphon can reduce the soil temperature obviously, and its long-term operation can maintain the stability of the embankment. Its cooling effect decreases for with the increase of the spacing. For the similar geological conditions, the effective operating radius of this type of thermosyphon is about 2.0 m, and the reasonable spacing between thermosyphons should be less than 4.0 m.