Subgrade protection technologies in permafrost regions are the focus of long-term researches for frozen soil scientists. The cooling effects of the new mechanical coolingthermosyphon ( NMCT) and the ordinary two-phase closed thermosyphon ( TPCT) are compared and analyzed based on field tests. The results show that: (1) The NMCT can make up for the deficiencies of the ordinary TPCT during warm seasons and take away the caloric from the active layer. In addition, it can increase the cold storage capacity and effectively protect the permafrost in both the warm and cold seasons. (2) In the cold and warm seasons, the temperature of the NMCT is lower than the that of the ordinary TPCT by 2. 77 to 0. 39 ℃ and 1. 22 to 0. 13 ℃ respectively in active layers; 3. 24 to 0. 52 ℃and 0. 55 to 0. 12 ℃ in permafrost layers. The annual average temperature of the NMCT is lower than the annual average temperature of the ordinary TPCT by 0. 74 ℃ in both active layers and permafrost layers. (3) The accumulated temperature of the NMCT is 1. 4 times to 2. 1 times in the warm seasons and1. 4 times to 1. 8 times in the cold seasons as much as that of the ordinary TPCT, and the former is1. 9 times the latter in a whole year. The research results can provide theoretical basis for the application of the NMCT technology in permafrost thermal stability maintenance.%多年冻土区路基防护技术是冻土科研人员长期研究的重点.基于多年冻土区现场试验,对研发的新型机械式制冷热管与普通热管的制冷效果进行对比分析.结果表明:(1)机械式制冷热管可以弥补普通热管在暖季不能工作的缺陷,能在暖季和寒季同时带走活动层中的热量,增加冷储量,有效保护多年冻土;(2)分别在寒季和暖季,机械式制冷热管比普通热管的侧壁温度在活动层中低2. 77～0. 39℃、1. 22～0. 13℃,在多年冻土层2. 0～6. 0 m深度范围中低3. 24～0. 52℃、0. 55～0. 12℃,机械式制冷热管年均温度比普通热管年均温度在活动层和多年冻土层中均低0. 74℃;(3)分别在暖季和寒季,机械式制冷热管的积温是普通热管积温的1. 4倍～2. 1倍、1. 4倍～1. 8倍,机械式制冷热管的年积温是普通热管年积温的1. 9倍.研究成果可为新型机械式制冷热管技术在多年冻土热稳定维护中的应用提供理论依据.
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