Abstract:In permafrost regions,the construction of railway should keep the subgrade frozen permanently so as to maintain the stability of the frozen subgrade. The main factors that influence the temperature field of the frozen subgrade are presented. Using the self-made experimental equipment for simulating frozen subgrade which is supported by horizontal pipes placed in the embankment,two means of maintaining frozen subgrade are simulated in the laboratory. One method is controlling natural cold energy only,and the other is controlling natural cold energy accompanied with artificial refrigeration simultaneously. The experimental results indicate that the subgrade temperature can not go down below 0 ℃ until at least 2 years after completion when only using natural cold energy in winter,but it can be below 0 ℃ at the completion of construction when using natural cold energy in winter and artificial refrigeration in summer. The advantages of sufficiently using natural cold energy can gradually emerge after 2 years. However,the superiority of using artificial refrigeration becomes weaken after 4 years.