Determination of technological parameters of rock freezing systems based on the condition of maintaining design thickness of ice wall

Artificial freezing ensures the formation of a temporary ice wall around the shaft under construction, which prevents groundwater penetration into the shaft and increases the strength of rocks around the unsupported walls of the shaft until the permanent support is erected. The purpose of the study is to carry out thermotechnical calculation of ice wall with subsequent theoretical analysis of changing ice wall thickness with shifting to the passive freezing stage. The idea of the study is to determine these technological parameters based on the condition of maintaining the design ice wall thickness at the stage of passive freezing. The methodology and results of thermotechnical calculation of ice wall for the clay layer as applied to the case of the shafts under construction of a potash mine in the Republic of Belarus are presented. The thermal calculation of the ice wall was carried out numerically in the ANSYS software package using the finite element method. The findings of the numerical multiparameter modeling allowed theoretical analysis of ice wall thickness decrease with shifting to the passive freezing stage with higher brine temperature. The decrease in ice wall thickness was studied both during normal operation of the freezing station and at emergency operation mode caused by the failure of one of the freezing columns. Special attention in the analysis was paid to studying the influence of the duration of the active freezing stage and the distance between the columns on the decrease in the ice wall thickness. When analyzing changes in ice wall thickness at different distances between the freezing columns, it was found that the most common column spacing in the range from 1.1 to 1.3 m requires observing restrictions on the duration of active freezing to prevent a critical decrease in ice wall thickness during the passive freezing stage or decreasing the distance between the freezing columns. In this case, preservation of positive dynamics of ice wall thickness growth is ensured. For the clay layer considered in the study and the distance between the columns from 1.1 to 1.3 m, the minimum time of active freezing is also about 4.3 months. As a result of the analysis, the technological parameters of the freezing system (duration of the active freezing stage and the distance between the freezing columns) were determined, at which the ice wall thickness at the passive freezing stage did not become lower than the minimum permissible values calculated based on the strength and creep conditions.

1. Semin M. A., Levin L. Y., Pugin A. V. Analysis of earth’s heat flow in artificial ground freezing. Journal of Mining Science. 2020;56(1): 149–158. https://doi.org/10.1134/S106273912001659X

2. Olkhovikov Yu. P. Support in permanent workings at potash and salt mines. Мoscow: Nedra Publ.; 1984. 238 p. (In Russ.)

3. Andersland O. B., Ladanyi B. Frozen ground engineering. John Wiley & Sons; 2003.

4. Nasonov I. D., Resin V. I., Fedyukin V. A., Shuplik M. N. Underground structure construction technology. Special methods of construction. Мoscow: Nedra Publ.; 1992. 351 p. (In Russ.)

5. Semin M. A., Levin L. Y., Bogomyagkov A. V. Theoretical analysis of frozen wall dynamics during transition to ice holding stage. Journal of Mining Institute. 2020;(243):319–328. (In Russ.). https://doi.org/10.31897/pmi.2020.3.319

6. Zhang B., Yang W., Wang B. Plastic design theory of frozen wall thickness in an ultradeep soil layer considering large deformation characteristics. Mathematical Problems in Engineering. 2018. https://doi.org/10.1155/2018/8513413

7. Kostina A., Zhelnin M., Plekhov O., Panteleev I., Levin L. Creep behavior of ice-soil retaining structure during shaft sinking. Procedia Structural Integrity. 2018; 13:1273–1278. https://doi.org/10.1016/j.prostr.2018.12.260

8. Vyalov S. S. Rheological properties and bearing capacity of frozen soils. Мoscow: USSR Academy of Sciences Publ.; 1959. 192 p. (In Russ.)

9. Dorman Ya. А. Special methods of work in subway construction. Мoscow: Transport Publ.; 1981. 302 p. (In Russ.)

10. Levin L. Yu., Kolesov E. V., Semin M. A. Dynamics of ice wall under conditions of damaged freezing pipes when shaft sinking. Mining Informational and Analytical Bulletin. 2016;(11):257–265. (In Russ.). URL: https://giab-online.ru/files/Data/2016/11/257_265_11_2016.pdf

11. Semin M. A., Zaitsev A. V., Parshakov O. S., Zhelnin M. S. Substantiation of technological parameters of thermal control of the frozen wall. Bulletin of the Tomsk Polytechnic University. Geo Assets Engineering. 2020;331(9):215–228. (In Russ.). https://doi.org/10.18799/24131830/2020/9/2824

12. Alzoubi M. A., Madiseh A., Hassani F. P., Sasmito A. P. Heat transfer analysis in artificial ground freezing under high seepage: Validation and heatlines visualization. International Journal of Thermal Sciences. 2019;139:232–245. https://doi.org/10.1016/j.ijthermalsci.2019.02.005

13. Marwan A., Zhou M. M., Zaki Abdelrehim M., Meschke G. Optimization of artificial ground freezing in tunneling in the presence of seepage flow. Computers and Geotechnics. 2016;75:112–125. https://doi.org/10.1016/j.compgeo.2016.01.004

14. Trupak N. G. Freezing of soils in underground construction. Мoscow: Nedra Publ.; 1974. 280 p. (In Russ.)

15. Yao Z., Cai H., Xue W., Wang X., Wang Z. Numerical simulation and measurement analysis of the temperature field of artificial freezing shaft sinking in Cretaceous strata. AIP Advances. 2019;9(2):025209. https://doi.org/10.1063/1.5085806

16. Voller V. R., Prakash C. A fixed grid numerical modelling methodology for convection-diffusion mushy region phase-change problems. International Journal of Heat and Mass Transfer. 1987;30(8):1709–1719. https://doi.org/10.1016/0017-9310(87)90317-6

17. Schneider M. C., Beckermann C. A numerical study of the combined effects of microsegregation, mushy zone permeability and fllow, caused by volume contraction and thermosolutal convection, on macrosegregation and eutectic formation in binary alloy solidification. International Journal of Heat and Mass Transfer. 1995;38(18):3455–3473. https://doi.org/10.1016/0017-9310(95)00054-D

18. Alzoubi M. A., Nie-Rouquette A., Sasmito A. P. Conjugate heat transfer in artificial ground freezing using enthalpy-porosity method: experiments and model validation. International Journal of Heat and Mass Transfer. 2018;126:740–752. https://doi.org/10.1016/j.ijheatmasstransfer.2018.05.059

19. Del Giudice S., Comini G., Lewis R. W. Finite element simulation of freezing processes in soils. International Journal for Numerical and Analytical Methods in Geomechanics. 1978;2(3):223–235. https://doi.org/10.1002/nag.1610020304

20. Parshakov O. S. Review of emergency situations during construction of mine shafts by a special method of artificial freezing of rocks. Gornoe ekho. 2019;(2):89–92. (In Russ.). https://doi.org/10.7242/echo.2019.2.21

21. Palankoev I. М. Analysis of the causes of emergencies when sinking vertical shafts using artificial ground freezing. Bezopasnost’ truda v promyshlennosti. 2014;(2):49–53. (In Russ.).

22. Levin L. Y., Semin M. A., Zaitsev A. V. Adjustment of thermophysical rock mass properties in modeling frozen wall formation in mine shafts under construction. Journal of Mining Science. 2019;55(1):157–168. https://doi.org/10.1134/S1062739119015419

23. Sanfirov I. A., Yaroslavtsev A. G., Chugaev A. V., Babkin A. I., Baibakova T. V. Frozen wall construction control in mine shafts using land and borehole seismology techniques. Journal of Mining Science. 2020;56(3):3597–369. https://doi.org/10.1134/S1062739120036641

24. Hass H., Schaefers P. Chapter 54. Application of ground freezing for underground construction in soft ground. In: Kwast E. A., Bakker K. J., Broere W., Bezuijen A. (eds.) Geotechnical Aspects of Underground Construction in Soft Ground: Proceedings of the 5th International Symposium TC28. Amsterdam, the Netherlands, 15–17 June 2005. Pp. 405–412. URL: https://www.issmge.org/uploads/publications/6/11/2005_054.pdf

25. Parshakov O. S. Development of an automated system for thermometric control of ice walls. [Ph.D. thesis in Engineering Science]. Perm; 2020. 140 p. (In Russ.)