Thermal monitoring of railway subgrade in a region of ice-rich permafrost, Yakutia, Russia

Abstract

This article presents the results of geocryological investigations conducted in the ice-rich permafrost section of the railway during the geotechnical exploration, design and construction stages, as well as prior to its permanent operation.Changes in the thermal regime of the subgrade and embankment soils have been quantified associated with the wide use of thermosyphons and insulation materials. The observations indicate rising of the permafrost table and cooling of the subgrade under high and low embankments, and active-layer deepening and ground temperature warming on the right-of-way along the railroad. Where a zero-slope fill is placed with removal of the active layer, perennial thaw bulbs have developed in the subsoil. Degradation of ice-rich permafrost is observed on the cut slopes and ditches in the cut sections. Thermosyphons on the berms in combination with Penoplex insulation have shown a cooling effect on the subgrade and permafrost table. Overhanging snow sheds on the embankment slopes have also proved to be beneficial in reducing subgrade temperatures.