Institute of Integrated Mineral Development – IPKON, Russian Academy of Sciences, Moscow, Russia:

A. L. Karchevsky, Leading Researcher, Doctor of Physico-Mathematical Sciences
L. A. Nazarova, Leading Researcher, Doctor of Physico-Mathematical Sciences, lanazarova@ngs.ru
V. N. Zakharov, Director, Corresponding Member of the Russian Academy of Sciences
L. A. Nazarov, Leading Researcher, Doctor of Physico-Mathematical Sciences

Seismic monitoring is an integral element of a hard mineral mining technology. The seismic data interpretation is possible with various approaches (statistical, deterministic, integrated) and is aimed to obtain information on geomechanical conditions of rocks. This article suggests the method to recover stress field in coal and rock mass based on inverse problem solution. Within a two-dimensional linearly elastic model of coal bed deformation under mining, the authors formulate and prove resolvability of an inverse problem on the conditions in horizontal contact zones based on the data on distribution of normal octahedral stress s(х):
• using acoustic probing or tomography, the velocity V(x) is determined in the middle section of a coal bed;
• based on the lab test data on rocks in the bed under mining, the empirical relation V = F(s) is obtained.
Using the results, the input data s(х) = F^–1(V(x)) are calculated for the inverse problem to determine the boundary conditions and, thus, to recover the stress–strain state in the coal bed. The mechanism of initiation and development of an outburst has been proposed and theoretically validated: the presence of areas with low cohesion in the contact zones between coal bed and enclosing rock mass conditions formation and expansion of horizontal tensile stress zones at the coal bed edges in the course of heading, which induces the risk of splitting-off of coal due to its low tensile strength.
The study has been supported by the Russian Science Foundation, Project No. 16-17-00029.

1. Zakharov V. N. Seismoacoustic forecasting and control of state and properties of rocks during the coal deposit mining. Moscow : IGD imeni A. A. Skochinskogo, 2002. 172 p.
2. Zakharov V. N., Malinnikova O. N., Averin A. P. Modeling mining-induced vibrations in production face area in coal-rock mass. Gornyi Zhurnal. 2016. No. 12. pp. 28–32. DOI: 10.17580/gzh.2016.12.06
3. Turchaninov I. A., Iofis M. A., Kasparyan E. V. Basis of rock mechanics. Second edition, revised and enlarged. Leningrad : Nedra, 1989. 488 p.
4. Seidle J. Fundamentals of Coalbed Methane: Reservoir Engineering. Oklahoma : PennWell Corporation, 2011. 401 p.
5. Mining encyclopedia. Ed.: A. E. Kozlovskiy. Moscow : Sovetskaya entsiklopediya, 1991. Vol. 5. USSR – Yashma. 541 p.
6. Mironov K. V. Reference book of geologist-collier. Moscow : Nedra, 1982. 311 p.
7. Dorokhov D. V., Sivokhin V. I., Podtykalov A. S., Kostyuk I. S. Technology of underground mining of stratified mineral deposits : tutorial. Donetsk : DonGTU, 1997. 344 p.
8. Shkuratnik V. L., Nikolenko P. V. Methods of definition of stress-strain state of rock mass. Moscow : Gornaya kniga, 2012. 112 p.
9. Kocharyan G. G. Geomechanics of faults. Moscow : Geos, 2016. 423 p.
10. Baklashov I. V. Geomechanics. Moscow : Izdatelstvo MGGU, 2004. Vol. 1. Basis of geomechanics. 208 p.
11. Nazarova L. A., Nazarov L. A., Protasov M. I. Reconstruction of 3D stress field in coal-rock mass by solving inverse problem using tomography data. Fiziko-tekhnicheskie problemy razrabotki poleznykh iskopaemykh. 2016. No. 4. pp. 12–21.
12. Atkin R. J., Fox N. An Introduction to the Theory of Elasticity. Dover Publications, 2013. 256 p.
13. Cao A., Dou L., Cai W., Gong S., Liu S. et al. Case study of seismic hazard assessment in underground coal mining using passive tomography. International Journal of Rock Mechanics and Mining Sciences. 2015. Vol. 78. pp. 1–9.
14. Al Heib M. Numerical and Geophysical Tools Applied for the Prediction of Mine Induced Seismicity in French Coalmines. International Journal of Geosciences. 2012. Vol. 3, No. 4. pp. 834–846.
15. Nazarov L. A., Nazarova L. A., Yaroslavtsev A. F., Miroshnichenko N. A., Vasileva E. V. Evolution of stress fields and induced seismicity in operating mines. Fiziko-tekhnicheskie problemy razrabotki poleznykh iskopaemykh. 2011. No. 6. pp. 6–13.
16. Karchevskiy A. L. Calculation of stresses in a coal seam in presence of gas diffusion. Sibirskiy zhurnal industrialnoy matematiki. 2016. Vol. 19, No. 4. pp. 31–43.
17. Khalilov S. A. About a set of coordinate functions for solving the boundary-value problems of plate and shell theory. Flying vehicles’ design strength : collection of scientific proceedings. Kharkov : KhAI, 1977. Iss. 4. pp. 60–65.
18. Farmer I. Coal Mine Structures. Springer, 1985. 287 p.
19. Bulat A. F., Zvyagilskiy E. L., Lukinov V. V., Perepelitsa V. G., Pimonenko L. I. et al. Coal-rock massif of Donbass as a heterogeneous environment. Kiev : Naukova dumka, 2008. 411 p.
20. Westman E., Luxbacher K., Schafrik S. Passive seismic tomography for three-dimensional time-lapse imaging of mining-induced rock mass changes. The Leading Edge. 2012. Vol. 31, No. 3. pp. 338–345.
21. Morcote A., Mavko G., Prasad M. Dynamic elastic properties of coal. Geophysics. 2010. Vol. 75, No. 6. pp. E227–E234.
22. Shkuratnik V. L., Nikolenko P. V., Koshelev A. E. Stress Dependence of Elastic P-Wave Velocity and Amplitude in Coal Specimens under Varied Loading Conditions. Fiziko-tekhnicheskie problemy razrabotki poleznykh iskopaemykh. 2016. No. 5. pp. 48–53.
23. Vasilev F. P. Numerical methods for extremum problem solving. Moscow : Nauka, 1988. 550 p.
24. Dyadkov P. G., Nazarov L. A., Nazarova L. A. Numerical modeling of stress state of the Earth’s crust and conditions of dynamic instability of seismic-active fractures during rifting. Geologiya i geofizika. 1997. Vol. 38, No. 12. pp. 2001–2010.
25. Shtumpf G. G., Ryzhkov Yu. A., Shalamanov V. A., Petrov A. I. Physical and technical properties of rocks and coals of Kuznetsk basin : reference book. Moscow : Nedra, 1994. 447 p.
26. Physical properties of rocks and minerals. Second edition, revised and enlarged : reference book. Ed.: N. B. Dortman. Moscow : Nedra, 1984. 455 p.
27. Khristianovich S. A., Kovalenko Yu. F. About the measurement of gas pressure in coal layers. Fizikotekhnicheskie problemy razrabotki poleznykh iskopaemykh. 1988. No. 3. pp. 3–24.