A self-adaption horizontal thermosyphon technology in uneven thermal control of roadway embankments in sub-arctic permafrost regions

Most roadways have differential solar absorption across the embankment in cold regions due to the slope-facing problem or the difference in slope surface conditions, which can cause uneven thermal distribution and result in longitudinal crack. How to efficiently adjust the uneven geotemperature is key. In this study, a field experiment was firstly performed to reveal the uneven temperature distribution in an embankment in Alaska. To solve the problem, a self-adaption horizontal thermosyphon technique was proposed. Series of laboratory tests were conducted to evaluate the heat control performance of the novel technique. The results indicate that the technique can effectively adjust the asymmetric geotemperature distribution and reduce the uneven deformation of the embankment. The difference in the horizontal geotemperature along the bottom of the embankment can be reduced by 86 %. Meanwhile, the lateral heat control distance of the horizontal thermosyphon can nearly reach 0.5 m in the model tests. The working performance is resulted from the self-adaption partial circulations of the working fluid within the horizontal thermosyphon. In addition, the novel technique has better adaptability for the roadway with any side-slope faces and severe environment than the existing techniques. The results of the research could contribute to the improvement of theory for a horizontal thermosyphon and provide a novel idea in heat control.