PSI - Issue 18

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

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Procedia Structural Integrity 18 (2019) 293–300

25th International Conference on Fracture and Structural Integrity Numerical simulation of freezing pipe deformation during artificial ground freezing Kostina A. a , Zhelnin M. 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 Abstract The present work is devoted to study of integrity of steel freezing pipes during artificial freezing of a rock mass and subsequent it thawing on the basis of a numerical simulation. To estimate pressure acting on the pipe by a surrounding soil, a thermo-hydro mechanical model is used. The constitutive relations of the model are derived within the framework of the linear theory of thermo poroelasticity under the assumptions that the rock mass is layered linear isotropic porous media that undergoes small deformation. The developed model allows one to take into account strain induced by frost heave and soil thawing. Strength analysis of the pipe is performed according to technical standard on the basis of the linear theory of elasticity. Several critical situations for pipe integrity such as nonhomogeneous distribution of the external pressure along the pipe wall and corrosion of the pipe wall is considered. 25th International Conference on Fracture and Structural Integrity Numerical simulation of freezing pipe deformation during artificial ground freezing Kostina A. a , Zhelnin M. a, *, Plekhov O. a , Panteleev I. a , Levin L. b a Institute of Cont 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 Abstract The prese t work is devoted to study of integrity of steel fre zing pip s during artificial freezing of a rock mass and subsequent it thawing on the basis of a numerical simulation. To estimate pressure acting on the pipe by a surrounding soil, a thermo-hydr - mechanical model is used. The constitutive relations of the model are derived within the framework of the linear theory of thermo poroelasticity under the assumptions that the rock mass is layered linear isotropic porous medi that undergoes small deformation. The developed m del allows one to take into account strain induced by frost heave and soil thawing. Strength analysis of the i is performed according to technical standard on the basis of the linear theory of elasticity. Several critical situations for pipe integrity such as nonhomogeneous distribution of the external pressure along the pipe wall and corrosion of the pipe wall is considered.

© 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo.

Keywords: artificial ground freezing; numerical simulation; pipe integrity; thermo-hydro-mechanical model Keywords: artificial ground freezing; numerical simulation; pipe integrity; thermo-hydro-mechanical model

1. Introduction The artificial ground freezing (AGF) technology has worldwide applications for a construction of a vertical mine shafts. Freezing of water in pores allows one to consolidate ground and to reduce its permeability. Therefore, AGF is used for stabilization of weak soils and prevent groundwater filtration into an excavation. The cooling system for AGF consists of a network of wells placed around a vertical mine shaft under construction. In the wells freezing pipes are installed that are connected to a refrigeration installation. Due to heat extraction 1. Introduction The artificial ground freezing (AGF) technology has worldwide applications for a construction of a vertical mine shafts. Freezing of water in pores allows one to consolidate ground and to reduce its permeability. Therefore, AGF is used for stabilization of weak soils and prevent groundwater filtration into an excavation. The cooling system for AGF consists of a network of wells placed around a vertical mine shaft under construction. In the wells freezing pipes are installed that are connected to a refrigeration installation. Due to heat extraction

2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. 2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. * Correspon ing 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 Gruppo Italiano Frattura (IGF) ExCo. 10.1016/j.prostr.2019.08.168