The fields of deformations and displacements of the marginal zone of the coal seam are determined on the basis of the associated law of plastic flow, in which the stress components are constructed within the framework of the previously developed model of the geomechanical state of the rock mass containing the coal seam and the workings passed through it. In this model, the stresses in the limiting zone of the seam are determined by the methods of mechanics of the bulk medium developed by the soviet scientist V.V. Sokolovsky.
The condition for the destruction of the part of the marginal zone of the coal seam, which, according to the Coulomb-Mohr criterion, passed into the limit state (without hardening), that corresponds to the idealized Prandtl diagram, is that it exceeds the limiting indicator of the intensity of plastic deformations corresponding to the deformations of the coal sample during its uniaxial destruction by compression. This indicator is determined by the results of laboratory experiments with coal samples, or on the basis of available reference information on the mechanical characteristics of coal seams. Destruction of the part of the seam may be accompanied by such a dynamic phenomenon as a rock burst.
Seam deformation in the extremely stressed zone is accompanied not only by a decrease in its thickness, but also by the movement of its edge into the goaf. With a significant size of the mined-out space, these displacements (bulging) can extend to several tens of centimeters.
2. Fisenko G.L. Limit states of rocks around workings. Moscow: Nedra, 1976. 272 p. (In Russ.).
3. Petukhov I.M., Linkov A.M. Mechanics of rock bursts and outbursts. Moscow: Nedra, 1983. 279 p. (In Russ.).
4. Guo H., Yuan L. An integrated approach to study of strata behaviour and gas flow dynamics and its application. International Journal of Coal Science & Technology. 2015. №. 2. pp. 12–21.
5. Winton J.G. A review of energy associated with coal bursts. International Journal of Mining Science and Technology. 2018. Vol. 28. Iss. 5. pp. 755–761. DOI: 10.1016/j.ijmst.2018.08.004
6. Cherdantsev N.V. A Certain Approach to Constructing the Solution to the Problem of Coal and Methane Outburst from a Marginal Seam Zone. Mechanics of Solids. 2022. Vol. 57. Iss. 8. pp. 2128–2150. DOI:10.3103/S0025654422080301
7. Bulychev N.S. Mechanics of the underground structures. Moscow: Nedra, 1994. 382 p. (In Russ.).
8. Protosenya A.G., Stavrogin A.N. Mechanics of the rocks deformation and destruction. Moscow: Nedra, 1992. 224 p. (In Russ.).
9. Galindo R.A., Serrano A., Olalla C. Ultimate bearing capacity of rock masses based of modified Mohr — Coulomb strength criterion. International Journal of Rock Mechanics and Mining Sciences. 2017. Vol. 93. pp. 215–225. DOI: 10.1016/ j.ijrmms.2016.12.017
10. Cherdantsev N.V. Approach to Constructing a Hydraulic Fracture Trajectory in a Rock Mass Near a Mine Working. Mechanics of Solids. 2020. Vol. 55. Iss. 8. pp. 1372–1391. DOI: 10.3103/S0025654420080063
11. Cherdantsev N.V. About One Version of the Stress State Calculation of the Seam Worked out by Face. Bezopasnost truda v promyshlennosti = Occupational Safety in Industry. 2020. № 8. pp. 23–28. (In Russ.). DOI: 10.24000/0409-2961-2020-8-23-28
12. Kachanov L.M. Fundamentals of the theory of plasticity. Moscow: Nauka, 1969. 420 p. (In Russ.).
13. Aleksandrov A.V., Potapov V.D. Fundamentals of the theory of elasticity and plasticity. Moscow: Vysshaya shkola, 1990. 400 p. (In Russ.).