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Earth’s Cryosphere

2025 year, number 2

CALCULATIONS OF FROZEN SOIL THAWING AND REFREEZING PROCESSES NEAR DEVELOPMENT WELLS

J.B. Gorelik, I.V. Zemerov
Tyumen Research Centre, Siberian branch of the Russian Academy of Sciences, Earth Cryosphere Institute, Tyumen, Russia
Keywords: permafrost, well’s support, thawing, refreezing, calculation methods

Abstract

Calculation for examples of frozen soils with temperatures of -3 and -6 °C using both numerical and analytical methods demonstrated that for an analytical description of the frozen soil thawing during the well operation period, the problem statement in the Leibenson form can be used with the assignment of an exact solution for the temperature in an unlimited part of space. The solution for the thawing radius in such a problem is written in a form close to self-similar. An exact analytical solution is obtained for the equation describing the change in the talik size upon its refreezing. It is shown that the time of refreezing of the talik depends not only on its size but also on the history of its formation. It is established that there is a boundary soil temperature value, below which the talik refreezing time is less than the time of its formation. At a soil temperature above the boundary value, the relationship between these times is inverse. At the final stages of well support design, it is recommended to rely on the results of numerical calculations of the parameters of thawing and refreezing processes using high-quality software products. The accuracy of the analytical method does not fully meet the requirements for the accuracy of the forecast during design, but it allows for fairly reliable tracking of trends in the evolution of process parameters, preserves the order of the calculated values, and ensures a high speed of their assessment. This allows us to recommend the use of the analytical method for operational assessments of thawing and refreezing processes at the preparatory stages of surveys for construction and in the design of well support structures, in monitoring studies, as well as at the stages of debugging standard computing programs for a specific task.