PSI - Issue 17

Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2019) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2019) 000 – 000

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Procedia Structural Integrity 17 (2019) 316–323

ICSI 2019 The 3rd International Conference on Structural Integrity Numerical simulation of soil stability during artificial freezing Zhelnin M. a, *, Kostina A. a , Plekhov O. a , Panteleev I. a , Levin L. b a Institute of Continuous Media Mechanics of the Ural Branch of Russian Academy of Science, Perm 614013, Russia b Mining institute of the Ural Branch of Russian Academy of Sciences, Perm 614007, Russia ICSI 2019 The 3rd International Conference on Structural Integrity Numerical simulation of soil stability during artificial freezing Zhelnin M. a, *, Kostina A. a , Plekhov O. a , Panteleev I. a , Levin L. b a Institute of Conti uou Media Mechanics of the Ural Br ch of Russian Academy of Science, Perm 614013, Russia b Mining institute of the Ural Branch of Russian Academy of Sciences, Perm 614007, Russia Artificial ground freezing is an efficient method for construction of vertical mine shafts under hard geological and hydrological conditions. The present article is devoted to a numerical simulation of mechanical behavior of soils surrounding freezing wells during a shaft sinking with a use of the artificial ground freezing method. The numerical simulation is carried out on the basis of a thermo-hydro-mechanical model of freezing process in a water saturated rock mass. Constitutive relations are derived within framework of thermo-poromechanics in consideration of the phase transition. Description of the mechanical behavior of soils is performed in the elasto-plastic formulation. The model allows one to take into consideration an influence of frost heave and temperature change on strain of soils under freezing process. Plastic strain is estimated with a use Drucker-Prager criterion. The numerical simulation of artificial freezing of a rock mass has been carried out for two cases. In the first case a response of soils adjacent to freezing wells on an application of the AGF method and a shaft sinking has been analyzed. In the second case stress strain state in a neighborhood of the freezing well has been determined. It has been shown that the artificial freezing and excavation works leads to an increase of mechanical pressure in near-wellbore domains. Frost heave and temperature deformation induced by the artificial freezing cause displacement of soil in the vertical and horizontal directions. Artificial ground freezing is an efficient method for construction of vertical mine shafts under hard geological and hydrological conditions. The present article is devoted to a numerical simulation of mechanical behavior of soils surrounding freezing wells during a shaft sinking with a use of the artificial ground freezing method. The numerical simulation is carried out on the basis of a thermo-hydro-mechanical odel of freezing process in a water saturated rock mass. Constitutive relations are derived within framework of thermo-poromechanics in consideration of the phase transition. Description of the mechanical behavior of soils is performed in the elasto-plastic formulation. The model allows one to take into consideration an influence of frost heave and temperature change on strain of soils under freezing process. Plastic strain is estimated with a use Drucker-Prager criterion. The numerical simulation of artificial freezing of a rock mass has been carried out for two cases. In the first case a response of soils adjacent to freezing wells on an application of the AGF method and a shaft sinking has been analyzed. In the second case stress strain state in a neighborhood of the freezing well has been determined. It has been shown that the artificial freezing and excavation works leads to an increase of mechanical pressure in near-wellbore domains. Frost heave and temperature deformation induced by the artificial freezing cause displacement of soil in the vertical and horizontal directions. Abstract Abstract

© 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers.

Keywords: artificial ground freezing, numerical simulation, frost heave, thermo-hydro-mechanical model Keywords: artificial ground freezing, numerical simulation, frost heave, thermo-hydro-mechanical model

1. Introduction 1. Introduction

Elaboration of potash deposits is frequently accompanied by geotechnical construction problems related to presence of groundwater and weak, unstable soil stratums in a rock mass. The artificial ground freezing (AGF) Elaboration of potash deposits is frequently accompanied by geotechnical construction problems related to presence of groundwater and weak, unstable soil stratums in a rock mass. The artificial ground freezing (AGF)

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

2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. 2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers.

2452-3216  2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. 10.1016/j.prostr.2019.08.042