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

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.