PSI - Issue 32

M. Zhelnin et al. / Procedia Structural Integrity 32 (2021) 238–245 M. Zhelnin/ Structural Integrity Procedia 00 (2021) 000–000

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thermal, hydraulic and mechanical processes is provided thorough the Clausius-Clapeyron equation, constitutive relations of the Coussy poromechanics, volume heat and mass source terms, convective term and empirical equations for describing a change of soil properties with temperature. Also in the model a volumetric inelastic strain is included to describe a volumetric expansion of the soil due to frost heave. The equations of the model were implemented in the Comsol Multiphysics software and solved using the finite element method. The proposed model was applied for numerical simulation of artificial freezing process of a soil stratum for a vertical shaft sinking. An analysis of the mesh convergence was shown that a use of the developed numerical scheme allowed one to obtain a convergent numerical solution of the equations of the model. Results of the performed numerical simulation demonstrated that the model is able to describe a frozen wall formation with considering such important phenomena such as water migration to the freezing front, frost heave in frozen zone and the soil consolidation in the unfrozen zone. It was shown that due to water migration an intensive frost heave evolves in the frozen zone. The frost heave leads to a rise of the porosity and inelastic volumetric expansion of the freezing soil. A water outflow from the unfrozen zone to the frozen zone contributes to soil consolidation near the sides of the frozen wall and in the region adjusting to the middle plane. After a closure of the frozen wall an increase in its thickness causes an abrupt rise of the pore water pressure in the unfrozen soil inside the wall due to a mechanical impact of the frozen soil. Nevertheless, during the freezing a strong cryogenic suction induces water migration to the inner side of the wall as a result the pore pressure decreases. Acknowledgements The reported study was funded by RFBR, project number 19-31-90107 References [1] Levin, L., Golovatyi, I., Zaitsev, A., Pugin, A., Semin, M., 2021. Thermal monitoring of frozen wall thawing after artificial ground freezing: Case study of Petrikov Potash Mine. Tunnelling and Underground Space Technology 107, 103685. https://doi.org/10.1016/j.tust.2020.103685 [2] Kostina, A., Zhelnin, M., Plekhov, O., Panteleev, I., Levin, L., Semin, M., 2020. An Applicability of Vyalov’s equations to ice wall strength estimation. Frattura ed Integrità Strutturale 14(53), 394–405. https://doi.org/10.3221/IGF-ESIS.53.30 [3] Harlan, R.L., 1973. Analysis of coupled heat ‐ fluid transport in partially frozen soil. Water Resources Research 9(5), 1314 – 1323. https://doi.org/10.1029/WR009i005p01314 [4] Kurylyk, B.L., 2013. Watanabe, K. 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