Keyword: «frozen soil»

Main pipelines are subjected to various exogenous processes in the permafrost area. The behavior of underground pipelines in permafrost soils is one of the main factors that affect their reliability. Frost heaving is one of the most dangerous processes that recur annually and can lead to pipeline bends in the vertical plane, sagging of individual sections, displacement, or loss of longitudinal stability. The article shows that the long-term monitoring of the planned-high-altitude position of the main gas pipeline revealed a section of the shore slope on the Khatasskaya channel of the river Lena, where intense deformations occur twice a year. The survey procedure is presented, and the graphs of their positions are provided. The changes in the planned-high-altitude position of the pipeline reach one meter. Thus, our hy-pothesis is confirmed.

The article presents data on the planned and high-altitude position of the pipeline for the period of November 2024 – April 2025. The measurements were conducted in April, when the pipeline is in frozen soil, and in November, when the soil around the pipeline is thawed. It has been confirmed that the processes of freezing and thawing of the soil around the main gas pipeline on the main terrace of the floodplain zone and on the channel are uneven. The changes in the high-altitude position of the pipeline can reach up to 2.0 m.

The paper presents the results of the development and testing of a technique for non-invasive monitoring of pore moisture dynamics in a dispersed material (sand) under freezing conditions. The technique is based on the use of a specialized cylindrical capacitance sensor, which allows reconstructing the spatial distribution of dielectric permittivity correlated with moisture content. Laboratory experiments involved unidirectional freezing of soil samples with different initial moisture contents. Based on a series of measurements, a three-dimensional reconstruction of the dielectric constant was performed. The technique was verified by comparison with data from the reference gravimetric method. Satisfactory quantitative agreement between the moisture distributions obtained by the capacitance and gravimetric methods is demonstrated, confirming the adequacy of the proposed approach.