Soil freezing is observed throughout almost the entire forested area of the Russian Federarion in winter. The effect of negative temperatures on dusty-clay soils causes a number of adverse processes that change the properties of the soils themselves. One of the most unfavorable of these processes is the accumulation of moisture in soils under the influence of the movement of the freezing front. When freezing, water-saturated clay soils increase dramatically in volume. This leads to the appearance of frost heaving in the active zone of the forest roadbed, which has an extremely adverse effect on the structure of the entire pavement and can lead to damage to the pavement with a sharp deterioration in the transport and operational qualities of forest roads. To combat frost heaving, it is necessary to study the patterns of changes in the water-thermal regime of road structures. The depth of freezing of the pavement and the roadbed is of the greatest importance for predicting frost heaving and developing measures to combat this phenomenon. The article describes the developed system for monitoring the temperature of the road structure to a depth of 3 m and the measurement results which allow us to evaluate the temperature change at different depths from the road surface and determine the freezing depth. A total of 32 sensors have been installed with a step of 10 cm. A numerical simulation of the freezing process of the pavement and the upper part of the roadbed of a forest road has been performed, with the results compared with the indicators of field observations. Good data convergence has been revealed. According to the results of experimental studies, the freezing value has been 173 cm, and according to the results of numerical simulation - 190 cm. The average error in the results of numerical simulation of the freezing process of the pavement and the upper zone of the forest roadbed has been 8-10 % compared to the experimental data.

Xing'anling-Baikal permafrost is located in the southern edge of the Northern Hemisphere permafrost, which is one of the most important regions of permafrost changes. Based on the monthly meteorological data and circumpolar active layer monitoring data in the last few decades, we analyzed the changes in the depth of seasonal freezing (DSF) and the thermal regime of Xing'anling-Baikal permafrost in China, and compared the state with that of the permafrost in Mongolia at the same latitude (LAT). The Xing'anling-Baikal permafrost in China was not connected in the section. The DSF changed between 0.78 and 3.25m. In the study area, DSF was the thickest in Tulihe and reduced to around. The change rate reached -16.0-4.9cm/a and decreased in most areas. The ground temperature raised at a rate of 0-0.41 degrees C/a, whereas that of other few areas decreased with a rate of -0.35 degrees C/a. Freezing duration spanned 141-176days. The changes were related to air temperature, altitude, LAT, and precipitation in the local area. Compared with the state of permafrost in Mongolia at the same LAT, the permafrost in China exhibited a faster rate of degradation. The permafrost in the Xing'anling area significantly responded to climate change. The results will aid in understanding the temporal and spatial variation in local permafrost and provide relevant verification for regional permafrost.