PSI - Issue 28

A. Prokhorov et al. / Procedia Structural Integrity 28 (2020) 1579–1589 Author name / Structural Integrity Procedia 00 (2019) 000–000

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At the figure 7b we can see an inhomogeneous distribution of ice content thought the specimen length. Initial moisture of the specimen was about 80%. In the figure we can see that on the side which was contact with freezing module, ice content closes to 95%. On the another side of specimen this value is about 75%. It means that during the freezing water migrates from the unfrozen part of specimen to the frozen one. 5. Conclusion The analysis of the readings of the monitoring system performed on the basis of the results of numerical modeling allows us to conclude that the volumetric expansion of the saturated soil caused by the frost heave occurs during the entire freezing period at temperatures much lower than the temperature of the onset of the phase transition. The calculation results show that this feature is associated with the gradual transition of residual moisture to ice. The distribution of deformations in the soil is nonhomogeneous and changes as it freezes. Comparison of the readings of the thermocouple located in the center of the laboratory sample with the simulation results showed that the proposed model allows a fairly accurate description of the temperature evolution. The maximum deviation is 1.4 K and is observed when the temperature abrupt reduces after the dissipation of the main part of the latent heat of the phase transition. It follows that the presented thermo-hydro-mechanical model can be used for temperature compensation of readings of deformation optical fiber sensors. At the same time, the numerical curves of deformation changes differ from the readings of fiber-optic sensors more significantly. Despite the fact that the values of the calculated deformations are close to the experimental ones, their qualitative behavior is different. The reason for this difference remains unclear and may be associated with both the complex interaction of the soil and fiber-optic sensors during the freezing process, and the insufficiently accurate description of this process by the developed thermo-hydro-mechanical model. Acknowledgements The work was supported by the Russian Science Foundation (grant No. 17-11-01204). References Tsytovich N.A. Mekhanika merzlykh gruntov. — M: Vysshaya shkola, 1973. — 448 s. Buldovich S. N., Volokhov S. S., Garagulya L. S. et. al. Osnovy geokriologii CH.5. Inzhenernaya geokriologiya. Pod red Yershova E.D // MGU Moskva, 1999. — 526 s. Vyalov S.S., Gorodetskiy S.E. et. al. Prochnost' i polzuchest' merzlykh gruntov i raschety ledogruntovykh ograzhdeniy. — Izd-vo AN SSSR, 1962. — 254 s. Trupak N.G. Zamorazhivaniye gruntov v podzemnom stroitel'stve. – M: Nedra, 1974. – 280 s. Andersland O.B., Ladanyi B., An introduction to frozen ground engineering. –Dordecht, Springer Science & Business Media, 1994. – 213p Wen Z., Sheng, Y. Jin H., Li S., Li G., Niu Y. Thermal elasto-plastic computation model for a buried oil pipeline in frozen ground //Cold Regions Science and Technology. – 2010. – Vol. 64. – №. 3. – pp. 248-255. Li H., Lai Y., Wang L., Yang X., Jiang N., Li L., Wang C., Yang B. Review of the state of the art: interactions between a buried pipeline and frozen soil // Cold Regions Science and Technology. – 2018. Yang P., Ke J.M., Wang J.G., Chow Y.K., Zhu F.B. Numerical simulation of frost heave with coupled water freezing, temperature and stress fields in tunnel excavation // Computers and Geotechnics. – 2006. – Vol. 33. – №. 6-7. – pp. 330-340. Han L., Ye G.L., Li Y.H., Xia X.H., Wang J.H. In situ monitoring of frost heave pressure during cross passage construction using ground-freezing method //Canadian Geotechnical Journal. – 2015. – Vol. 53. – №. 3. – pp. 530-539 Cai H., Li S., Liang Y., Yao Z., Cheng H. Model test and numerical simulation of frost heave during twin-tunnel construction using artificial ground-freezing technique //Computers and Geotechnics. – 2019. – Vol. 115. – pp. 103-155. Zhelnin M. et al. Numerical simulation of soil stability during artificial freezing //Procedia Structural Integrity. – 2019. – Vol. 17. – pp. 316-323. Kostina, A., Zhelnin, M., Plekhov, O., Panteleev, I., & Levin, L. Numerical simulation of freezing pipe deformation during artificial ground freezing. // Procedia Structural Integrity, 2019 – Vol.18 – pp. 293-300. Zhang L. et al. Investigation of the pore water pressures of coarse-grained sandy soil during open-system step-freezing and thawing tests //Engineering geology. – 2014. – Vol. 181. – pp. 233-248. Zhang L. et al. An investigation of pore water pressure and consolidation phenomenon in the unfrozen zone during soil freezing //Cold Regions Science and Technology. – 2016. – Vol. 130. – pp. 21-32. Zhang M. et al. Water–heat migration and frost-heave behavior of a saturated silty clay with a water supply //Experimental Heat Transfer. – 2017. – Vol. 30. – №. 6. – pp. 517-529.