PSI - Issue 32

Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2021) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2021) 000 – 000 Available online at www.sciencedirect.com ScienceDirect

www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia

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Procedia Structural Integrity 32 (2021) 101–108

© 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the XXIIth Winter School on Continuous Media Mechanics” Abstract Blasting and drilling operations during shaft sinking assume switching off the freezing columns which can lead to stability loss of a frozen wall and inrush of thawed soil into the stope. This work assesses safety of shaft sinking when freezing columns are turned off for a period of four days. It is assumed that the frozen wall loses its bearing capacity when displacement of its unfixed section exceeds 10 cm. Calculations are carried out for silt and sand stratums. Simulation was performed in finite-element software Comsol Multiphysics. Displacements of internal wall were obtained for two initial thicknesses of the frozen wall. In the first case the soil was frozen to the boundary of the future shaft, in the second case initial thickness corresponded to project documentation. It has been shown that frozen wall in silt stratum does not lose its bearing capacity even for complete defrosting. For sand stratum calculated time was equal to 85 days for the first thickness and 24 days for the second thickness of frozen wall. © 2021 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license ( https://creativecommons.org/licenses/by-nc-nd/4.0 ) Peer-review under responsibility of the scientific committee of the XXIIth Winter Scho ol on Continuous Media Mechanics” XXIIth Winter School on Continuous Media Mechanics Numerical simulation of stress-strain state in frozen wall during thawing A. Kostina a, *, M. Zhelnin a , O. Plekhov a , L. Levin b a Institute of cont uou media mechanics of the Ural branch of Russian academy of science, Ac.Koroleva st.,1, Perm, 614013, Russia b Mining institute of the Ural branch of Russian academy of science, Sibirskaya st.,78a, Perm, 614007, Russia Abstract Blasting and drilli g operations during shaf sinking assume switching off th freezing colum s ich can lead to stability loss of a rozen wall and inr sh of thawed oil into the stope. This work asses es s fety of shaft sinki g when fre zing columns are turned off for a period of fo r day . It is ssumed that the froze wall lose its bearing capacity when d splacem nt of it unfixed secti n exceeds 10 m. Calculatio s are carried out for silt and sa d stratums. S mulat on wa per ormed in finite-element sof w r Comso Multiphysics. Displacements of internal wall were obtained for two n tial thicknesses of the frozen wall. In the first case the soil was frozen to the b undary of the futu e shaft, in the second cas initial thi kness corresponded o projec document tion. It has been shown that frozen wall in silt stra um does not lo e its bearing capacity even for complete defrosting. For sand stratum calculated time was equal to 85 days for the first thickness and 24 days for the second thickness of frozen wall. © 2021 The Authors. Published by ELSEVIER B.V. This is an ope access article under CC BY-NC-ND lic nse ( https://creativecommons.org/licenses/by-nc-nd/4.0 ) Peer-review under responsibility of the scientific committee of the XXIIth Winter Scho ol on Continuous Media Mechanics” XXIIth Winter School on Continuous Media Mechanics Numerical simulation of stress-strain state in frozen wall during thawing A. Kostina a, *, M. Zhelnin a , O. Plekhov a , L. Levin b a Institute of continuous media mechanics of the Ural branch of Russian academy of science, Ac.Koroleva st.,1, Perm, 614013, Russia b Mining institute of the Ural branch of Russian academy of science, Sibirskaya st.,78a, Perm, 614007, Russia

Keywords: AGF; vertical shaft sinking; coupled problems; thawing Keywords: AGF; vertical shaft sinking; coupled problems; thawing

1. Introduction Artificial ground freezing (AGF) is widely applied to the formation of a temporary waterproof shield which provides safe excavation activities intended for vertical shaft sinking. The technology is implemented by a series of 1. Introduction Artifici l ground freezing (AGF) is widely applied to the formation of a temporary waterproof shield which provides safe excavation activities intended for vertical shaft sinking. The technology is implemented by a series of

* Corresponding author. Tel.: +7-342-237-8317; fax: +7-342-237-8487. E-mail address: kostina@icmm.ru * Correspon ing author. Tel.: +7-342-237-8317; fax: +7-342-237-8487. E-mail address: kostina@icmm.ru

2452-3216 © 2021 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license ( https://creativecommons.org/licenses/by-nc-nd/4.0 ) Peer-review under responsibility of the scientific committee of the XXIIth Winter School on Continuous Media Mechanics 2452-3216 © 2021 The Authors. Published by ELSEVIER B.V. This is an ope acces article under CC BY-NC-ND lic nse ( https://creativecommons.org/licenses/by-nc-nd/4.0 ) Peer-review under responsibility of the scientific committee of the XXIIth Winter School on Continuous Media Mechanics

2452-3216 © 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the XXIIth Winter School on Continuous Media Mechanics” 10.1016/j.prostr.2021.09.015