PSI - Issue 32

S. Yu. Devyatkov et al. / Procedia Structural Integrity 32 (2021) 56–63 S. Yu. Devyatkov / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 4. Subsidence of the soil along the benchmark, for various values of the coefficient of decreasing strength properties of the caved rocks relative to the enclosing rocks: Curve 1 shows data from mine surveying observations; Curve 2 – 0.200; Curve 3 – 0.067; Curve 4 – 0.040; Curve 5 – 0.029; Curve 6 shows a gradual decrease from 0.200 to 0.031. It can be assumed that softening of the caved rocks does not occur instantly to the final values of the deformation properties, but instead changes more slowly over time. If we take this into account by varying the properties of the caved rocks, we can achieve good agreement between the estimated subsidence and field observations of the displacement of the earth surface (Fig. 4, Curve 6). Our geomechanical model of the undermined mass can therefore be said to reflect the processes that are actually taking place. 4. Conclusions Our geomechanical model of the rock mass during a longwall face advance takes into account the main features of the mass structure and the technological parameters of mining. The model includes caving of the roof of the mined seam and the opening of clay contacts in the salt stratum, making it possible to study changes in the SSS of the undermined salt mass and revealing the laws governing the geomechanical processes that occur in this case. We have shown that it is possible to achieve agreement between the computational results for subsidence and field observations of the displacement of the earth surface by varying the properties of the caved rocks that form during the longwall face advance. This allows us to predict the displacement of the earth surface caused by stoping.

Acknowledgements The work was supported by the state task N0422-2019-0148-C-01. References

Baryakh, A. A., Fedoseev, A. K., 2011. Sinkhole formation mechanism. Journal of Mining Science. Vol. 47, 404 – 412. Baryakh, A. A., Shumikhina, A. Y., Toksarov, V. N., Lobanov, S. Y., Evseev, A. V., 2011. Criteria and features of failure in stratified roof of stopes in mining at Upper Kama potash salt deposit. GornyZh. Vol. 11, 15 – 19. Baryakh, A. A., Dudyrev, I. N., Asanov, V. A., Pan’kov, I. L., 1992. Interacti on of layers in salt deposit. Part I: Mechanical properties of joints. Journal of Mining Science. Vol. 28, no. 2, 145 – 149. Fadeev, A. B., 1987. Metodkonechnykhelementov v geomekhanike/Finite element method in geomechanics. Moscow: Nedra, pp. 221.