Method of Calculating Frost Penetration Depth for Railway Subgrade Considering Thermal Characteristics of Multilayer Materials

摘要

In severely cold regions of Japan, a conventional countermeasure against frost heaving is to replace the silt and loam layers with a non-frost material. The depth for replacement is determined by the frost penetration depth obtained from one-dimensional analysis using only the freezing index based on the annual average air temperature. This means that the thermal characteristics of the materials comprising the railway track-bed are not taken into consideration. This paper examines the applicability of advanced Berggren's method as a new technique to determine the freezing penetration depth. This method makes it possible to take into account the thermal characteristics of multilayer materials. We also introduce experiments for the determination of thermal characteristics.