Design Standard for Thermal Insulation and Drainage Facilities of Railway Tunnels in Cold Regions（寒区铁路隧道保温排水设施设计标准研究）

Targeted to the issue of lacking of systematic design standards for thermal insulation and drainage facilities of railway tunnels in cold regions, the authors propose the method of design division of railway tunnels in cold regions based on the division of cold regions, the current technical status of thermal insulation and drainage in tunnels, and the investigation on some tunnel freezing damage cases in northeastern China and the northern part of North China. Through analyzing the application conditions of the thermal insulation and drainage facilities and combining the measured temperatures in the operating tunnels and drainage facilities, the authors propose the suggested length for the thermal insulation and drainage facilities of tunnels in cold regions in different divisions. The results show that: (1)railway tunnels in cold regions may be classified into 5 divisions based on annual average temperature and average temperature in the coldest month; (2)the elevated thermal insulation ditch only adapts to the cold regions with a higher temperature; (3)an effective measure for thermal insulation and drainage in cold regions is to embed ditches into structures within a certain range from the portal; (4)the ditches may be arranged in structures for the trunk section of long tunnels equipped with thermal insulation measures; (5)for the tunnels with the necessary conditions available, the double spur grade and a steep gradient in the longitudinal slope may be applied, which is beneficial to improving drainage conditions and preventing the ditch from freezing.