中文摘要：

根据冻土学基本理论推导寒区隧道围岩的季节冻结深度和季节融化深度计算公式。根据传热学的热流连续定律,分别计算隧道围岩的热流量及含隔热层和衬砌隧道围岩的热流量;采用当量换算法推导出寒区隧道隔热层厚度及导热系数的计算公式。以青藏铁路风火山隧道为例,采用推导的隔热层厚度及导热系数公式进行计算。结果表明：隧道DK1 159＋046断面在2004年需要的隔热层厚度为4.1 cm,导热系数为0.03 W·（m·℃）^-1;考虑未来50年升温2.6℃,全隧道铺设厚度为5 cm、导热系数为0.03 W·（m·℃）^-1的隔热层,在前20年基本保证围岩不融化,在之后的30年围岩可能会融化。隧道实际的隔热层厚度为5 cm,导热系数为0.03 W.（m.℃）-1,2004年实测地温资料表明隧道围岩没有融化。此计算公式在寒区隧道设计的初始阶段,可用于指导隧道隔热层厚度和导热系数的参数设计。

英文摘要：

The formulae for calculating the seasonal frozen depth and seasonal thawing depth of the surrounding rock of cold region tunnel are derived according to the basic theory of geocryology. According to the heat flow continuous law of heat transfer theory, the heat flow of the surrounding rock inside the sea- sonal frozen or thawing depth and the heat flow of lining with insulation layer are calculated. Using equivalent conversion method, the calculation formulae of the thickness and conduction coefficient of the insulation layer are gained. The parameter calculation formulae of the thickness and conduction coefficient of the insulation layer are applied to Fenghuo Mountain tunnel on Qinghai-Tibet Railway. The ealeulation results show that the insulation layer, whose thickness is 4.1 cm and conduction coefficient is 0.03 W · （m ·C）^-1, is needed in the section DK1 159＋046 lining in 2004; considering the rise in climatic tem- perature of 2.6 ℃ in the future 50 years, laying the insulation layer with 5 cm in thickness and 0.03 W · （m·C）^-1 in conduction coefficient in the lining of the whole tunnel, the surrounding rock of tunnel will not thaw in the first 20 years, but with the climate changing warm, the surrounding rock of tunnel may be likely to thaw in the later 30 years. The actual thickness of insulation layer was 5 cm and the actual con- duction coefficient was 0.03 W · （m ·C）^-1 in Fenghuo Mountain tunnel, the actual observation records of the surrounding rock temperature of Fenghuo Mountain tunnel show that the surrounding rock did not thaw. The calculation formulae can be used to guide the thickness and the conduction coefficient design of the insulation layer of cold region tunnel in its preliminary design stage.