When building the mine workings in the underground conditions the initial stress-deformed state of the rocks around the workings changes with changing the value and sign. At the same time the selection of the appropriate support becomes more complicated. With the development of computer science and technology the numerical method has been widely used in solving the geotechnical problems. The numerical method for Phase 2 program is used to calculate internal forces when selecting the mine working supports in Kuangnin Province, Vietnam.
To solve the geomechanical problem the following initial data were adopted: the depth of the mine working deposit is 100 m, the width of mine workings is 5 m, and the height is 4.5 m. The following options are considered: a) B/D = 5/2; b) B/D = 5/4; c) B/D = 5/8; d) B/D = 5/16, the mine working is in the center of the rock thickness; e) B/D = 5/16, the mine working is at the top of the rock thickness; e) B/D = 5/16, the mine working is at the bottom of the rock thickness (where B is the width of the mine workings, D is the thickness of the rocks).
The results of the study showed that the geological properties of rocks, the angle of gradient and the thickness of the rocks, and also the place of location of the workings significantly effect the stress-deformed state of the rocks around the workings. The values of the bending moments in the support are changing at different thicknesses of the rocks, the diagrams of the internal forces are not symmetrical.
Maximum values of bending moments in the support can be reduced to 80 % when using adjustable elements of the metal support. When locating workings in the isotropic rock massif and at the ratio of the width of the mine working and the thickness of the rock massif 5/8 and 5/16, the stress-deformed state is symmetrical, and the best results are shown in the theory of rock pressure of Protodyakonov and P.M. Tsimbarevich. If the ratio of the width of the mine working to the thickness of the rock mass is less than 5/16, in practice the theory of V.T. Glushko suits most of all.
Tran Tuan Minh, Lecturer Xuan Nam Bui, Dr. Sci. (Eng.), Prof., Deputy Principal Kuang Khieu Chan, Cand. Sci. (Eng.), Lecturer Hanoi University of Mining and Geology, Hanoi, Vietnam Nguyen Quang Huy, Research Associate Transport Scientific and Technological Institute, Hanoi, Vietnam V.I. Golik, Dr. Sci. (Eng.), Prof., firstname.lastname@example.org FGBOU VPO «NCSTU», Vladikavkaz, Russia
1. Baklashov I.V., Kartoziya B.A. Mechanics of rocks. Moscow: Nedra, 1975. 271 p. (In Russ.).
2. Bulychev N.S. Mechanics of the underground structures: Textbook for Institutions of Higher Education. Moscow: Nedra, 1994. 382 p. (In Russ.).
3. Najafi A.B., Saeedi G.R., Farsangi M.A.E. Risk analysis and prediction of out-of-seam dilution in longwall mining. International Journal of Rock Mechanics and Mining Sciences. 2014. Vol. 70. pp. 115–122.
4. Golik V., Komashchenko V., Morkun V., Gaponenko T. Improving the effectiveness of explosive breaking on the bade of new methods of borehole charges initiation in quarries. Metallurgical and Mining Industry. 2015. Vol. 7. № 7. pp. 383–387.
5.Chan Kuang Khieu, Buy Suan Nam, Belin V.A. Determination of the effect of the diameter of blasting holes on the coefficient of seismicity at mass explosions near the protected objects at the coal mine «Nuibeo» of Quang Ning province, Vietnam. Bezopasnost truda v promyshlennosti = Occupational Safety in Industry. 2017. № 7. pp. 15–18. (In Russ.).
6. Tran Tuan Minh. Research on stress state and deformation around big tunnels with excavation stages in bedding and non-homogeneous rock. Advances in mining and tunneling. Ha Noi: University of mining and geology, 2012. pp. 309–316.
7. Tran Tuan Minh. Information applycation for underground and mining construction, construction publishing house. Ha Noi, 2014.
8. Protosenya A.G., Kuranov A.D. Methods for forecasting the stress-deformed state of the mining massif at the combined development of Koashvinsk deposit. Gornyy zhurnal = Mining Journal. 2015. № 1. pp. 17–20. (In Russ.).
9. Yakovlev D.V., Tsirel S.V., Mulev S.N. Regularities of the development and methods of the operative assessment of the technogenic seismic activity at the mining enterprises and in mining regions. FTPRPI = FTPRPI. 2016. № 2. pp. 34–47. (In Russ.).
10. Anokhin A.G., Semenko K.A., Darbinyan T.P., Tsirel S.V., Mulev S.N. Methodology of accounting for the degree of influence of the ore-bearing massif displacement on seismic risk. Gornyy zhurnal = Mining Journal. 2014. № 4. pp. 19–24. (In Russ.).
11. Nguyen Quang Phich. Using numerical softwares for calculation underground constructions and mines. Ha Noi, 2007.
12. Dimitrios Kolymbas. Tunnelling and tunnel mechanics. Berlin: Springer - Verlag Berlin Heidelberg, 2005.
13. Haeri H., Shahriar K., Fatehi Marji M., Moarefvand P. Experimental and numerical study of crack propagation and coalescence in pre-cracked rock-like disks. International Journal of Rock Mechanics and Mining Sciences. 2014. Vol. 67. pp. 20–28.
14. Liang Z.Z., Xing H., Wang S.Y., Williams D.J., Tang C.A. A three-dimensional numerical investigation of the fracture of rock specimens containing a pre-existing surface flaw. Computers and Geotechnics. 2012. Vol. 45. pp. 19–33.
15. Protodyakonov M.M. The pressure of rocks and mine support. Part I. Pressure of rocks. Moscow–Leningrad: Gostekhizdat, 1931. 102 p. (In Russ.).
16. Tsimbarevich P.M. Mine support. Moscow–Kharkov: Ugletekhizdat, 1951. 608 s. (In Russ.).
17. Glushko V.T., Gavelya S.P. Assessment of the stress-deformed state of rock massifs. Moscow: Nedra, 1986. 221 p. (In Russ.).
18. Benardos A., Athanasiadis I., Katsoulakos N. Modern earth sheltered constructions: A paradigm of green engineering. Tunnelling and Underground Space Technology. 2014. Vol. 41. pp. 46–52.
19. Galvin J.M. Ground Engineering – Principles and Practices for Underground Coal Mining. Switzerland: Springer International Publishing, 2016. 684 p.
20. Jarvie-Eggart M.E. Responsible Mining: Case Studies in Managing Social & Environmental Risks in the Developed World. Englewood, Colorado: Society for Mining, Metallurgy and Exploration, 2015. 804 p.