PSI - Issue 32

I S Lomakin et al. / Procedia Structural Integrity 32 (2021) 117–123 I S Lomakin, A A Tsayukov / Structural Integrity Procedia 00 (2019) 000 – 000

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calculations were performed for the second calculation variant. As a result, it was found that the total caving thickness of the roof of the lower layer reached 0.7 m. At the same time, the degree of the interchamber loading here was 0.45 (an increase of 18 %), as for the interchamber loading of the pillar of the upper layer, it was 0.299 (an increase of 16 %). The contact opening depth is similar to the first variant. 4. Conclusion The geomechanical modeling of changes in the stress-strain state of the generalized two-layer chamber block showed that in case of the interlayer thickness of 3.9 m, the loading of the pillars on both layers turned out to be somewhat greater than being considered independently. This indicates that at such an interlayer thickness, there is an interconnected effect of the mined layers on the loading degree of the pillars. It is shown that the presence of thin clay interlayers at the top of the lower productive layer leads to a lamination and caving of the interlayer rocks. In accordance with the accepted criterion of the rock for the considered variants of the mining system, the total caving thickness was 0.6-0.7 m. The opening of the contacts reaches the base of the sylvinite bed in the interlayer. The maximum increase of the loading degree of the pillars of the productive bed zone was 25 % of the initial value when mining both productive layers using a combine having the largest cross-sectional area. Let us note that this model does not take into account the rheological properties of the salt rocks and there is no time factor. Also, the destruction of the walls of the mining and its relationship with the lamination of the interlayer was not considered. Thus, the obtained estimates have a preliminary nature, according to which it is possible to understand the lower limit of the increase in the loading degrees of the interchamber pillar. With a further development of the proposed model in order to improve it, it is expected that changes in the loading degree of the pillars will be even more significant. Acknowledgements The work was carried out with the financial support by the State Budgetary Assignment № 075 -03-2021-374 of 29.12.2020 «R esearch on deformation and failure pattern of quasi plastic rocks under complex loading Asanov, V.A., Evseev, A.V., Pankov, I.L., Toksarov, V.N., 2018. Investigation of deformation of rocks and elements of the pillar mining system. Mining Journal Vol. 6. Moscow: Ore and Metals, pp. 13-16. Asanov, V.A., Toksarov, V.N., Evseev, A.V., Bel’tyukov, N.L., 2012. Specific roof behavior in the southern wing of the Upper Kama potash salt deposit. Journal of Mining Science. Vol. 48, no. 1, pp. 71-75. Baryakh, A. A., Asanov, V. A., Pankov, I. L., 2008. Physical and mechanical properties of salt rocks of the Verkhnekamskoe potash deposit: textbook. Perm: Publishing house of Perm State Techical University. Baryakh, A.A., Dudyrev, I.N., Asanov, V.A., Pankov, I.L., 1992. Interaction of layers in salt massif. Part 1. Mechanical properties of contacts. Fiziko-TexhnicheskiyeProblemyRazrabbotkiPoleznykhIskopaemykh. no. 2, pp. 48-52. Baryakh, A.A., Samodelkina, N.A., 2007. To the calculation of pillar stability under condition of chamber mining. Journal of Mining Science. Vol. 43, no. 1, pp. 8-16. Baryakh, A.A., Fedoseev, A.K., 2011. Sinkhole formation mechanism. Journal of Mining Science. Vol. 47, no. 4, pp. 404-412. Fadeev, A.B., 1987. Finite element method in geomechanics. Moscow: Nedra. Goodman, R.E., 1974. The mechanical properties of joints. Advanced Rock Mechanics. Vol. 1, Pt. A, pp. 127-140. Groth, T., 1980. Description and applicability of the BEFEM code. Appl. Rock Mech. Mining. Proc. Conf. Lulea. 1 – 3 June, London, pp. 204 – 208. Kuznetsov, G.N., 1947. Mechanical properties of rock. Moscow: Ugletechizdat. Shevyakov, L. D., 1941. On the calculation of strength dimensions and deformations of pillars. Izv. USSR Academy of Sciences, OTN. no. 7, pp. 3-13, no. 8, pp. 3-13, no. 9, pp. 43-58. Tournaire, 1884. Des dimensions a donner auхpilliers des carriers et des pressions aux quelles les terrains sontsoumis dans les profondeurs. Annales des mine, 8 series, T. V. Zienkiewicz, O.C., Taylor, R.L., Zhu, J.Z., 2013. The finite element method: its basis and fundamentals. 7th ed. Oxford: Butterworth-Heinemann. https://doi.org/10.1016/C2009-0-24909-9 conditions» References