PSI - Issue 32

ScienceDirect StructuralIntegrity Procedia 00 (2021) 000 – 000 StructuralIntegrity Procedia 00 (2021) 000 – 000 Available online at www.sciencedirect.com Available online at www.sciencedirect.com Sci nceDire t Available online at www.sciencedirect.com ScienceDirect

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

Procedia Structural Integrity 32 (2021) 56–63

© 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 Stoping of potash seams during pillar mining is accompanied by deformations in underworked rock mass and the destruction of roof rocks and floors of mine workings in the extraction pillars of longwall faces. This type of mining can also cause sudden caving of the roof and seam floor in an extraction pillar of a longwall face, thus posing a threat to miners, leading to unplanned stoppages of mining operations and reducing the efficiency of mining. In addition, during the advance of a longwall face, subsidence of the soil surface occurs. It is therefore important to study the deformation of the soil surface and find ways of predicting this during the underground mining of potash seams. To evaluate the stress-strain state of the rock mass during longwall mining, a geomechanical model of potash seam mining was constructed under conditions of slice mining. This model took into account the main structural features of the underworked mass, and the caving of the roof of an underworked seam with filling of the worked-out longwall face and the opening of clay contacts in the salt stratum during mining operations. The results of mathematical modelling showed that a localised area of plastic deformation is formed in the soil, which is associated with the formation of opening mode fractures. At the same time, caving of the roof rock and simultaneous filling of the worked-out space take place, preventing further development of the rock jointing zones. The properties of the rocks from the caved roof determine the nature of this mass deformation. By varying these properties, we were able to achieve acceptable agreement between the estimated subsidence and field observations of the displacement of the earth surface. A comparative analysis of the estimated and actual subsidence shows that in order to yield an accurate description of the mass deformation, softening of the caved rocks should not take place immediately to give the final values of the deformation properties, but should change over time. © 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” Keywords: geomechanics; mathematical modeling; pillar mining; stress-strain state; earth surface deformations Abstract Stoping of potash seams during pillar mining is accompanied by deformations in underworked rock mass and the destruction of ro f rocks and floors of mine workings in the extraction pillars of longwall faces. This type of mining can also cause sudden caving of the roof and seam floor in an extraction pillar of a longwall face, thus posing a thr at to miners, leading to unplann d stoppages of mining operations and reducing the efficiency of mining. In addition, during the advance of a longwall face, subsidence of the soil surface occurs. It is therefore important to study the deformation of the soil surface and find ways of predicti g this during the underground mining of potash seams. To evaluate the stress-strain state of the rock mass during longwall mining, a geom chanical mo el of potash seam mining was constructed under conditions of slice mining. This model t ok into account the main structural features of the underworked m ss, a d the cavi g of the ro f of an underworked sea with filling of the worked-out longwall face nd the opening of clay cont cts i the salt stratum during mini g op rations. The results of mathematical modelling showed that a localised area f plastic deformation is formed in the soil, which is ass ciated with the for tion of opening mode fractures. At the same time, caving of the roof r ck and simultaneous filling of the w rked-out spac take place, prev ting further development of the rock jointi zones. The propertie of the rocks from the caved roof determin the natur of this mass deformation. By varying these properties, we w re able to achieve acceptable agreement between th estim ted subsidence and field observations of the displacement of the earth surface. A comparative nalysis of the estimat d and actual subsidenc shows that in order t yield an accurate description of the mass deform tion, softening of the caved rocks should not take place immediately to give the fin l values of the deformation properties, but should change over time. © 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” Keywords: geomechanics; mathematical modeling; pillar mining; stress-strain state; earth surface deformations XXIIth Winter School on Continuous Media Mechanics Estimation of earth surface deformations during pillar mining S. Yu. Devyatkov* Mining Institute of the Ural Branch of the Russian Academy of Science, 614007, Sibirskaya st., 78a, Perm, Russia XXIIth Winter School on Continuous Media Mechanics Estimation of earth surface deformations during pillar mining S. Yu. Devyatkov* Mining Institute of the Ural Branch of the Russian Academy of Science, 614007, Sibirskaya st., 78a, Perm, Russia

* Corresponding author. Tel.: +7-912-487-1588; fax: +7-342-216-7202. E-mail address: sd@mi-perm.ru * Corresponding author. Tel.: +7-912-487-1588; fax: +7-342-216-7202. E-mail address: sd@mi-perm.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 t he 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 t he 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.2021.09.009