Geomechanical research into surface coal mining in terms of geotechnical safety substantiation

Hysen Ahmeti¹, Edon Maliqi¹

¹University for Business and Technology, Pristina, Kosovo

Min. miner. depos. 2023, 17(3):22-31

https://doi.org/10.33271/mining17.03.022

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      ABSTRACT

      Purpose. The purpose of the present study is to determine the geomechanical parameters for calculating the stability of side slopes by partial and general angle in the working front to ensure the completeness of coal mining in accordance with geotechnical rules and standards based on the regulations (EC-7) of the Kosovo Energy Corporation, which is the state corporation, producing not only electricity in the Republic of Kosovo.

      Methods. In the course of the present study, 60 additional drillings were carried out to a depth of 150 m up to green clay contact to determine the coal thickness. It was realized using a Type EK-650 drilling machine and a drilling diameter of 145/101 mm. To determine the angle φ and cohesion C, two methods were used, such as the Direct test and the Triaxial test. To obtain the most accurate results, a mathematical model was used to derive geomechanical parameters for calculating the slope geometry for the design geometry, where coal is mined to achieve a safety factor according to geotechnical standards.

      Findings. The regularities of changes in surface gloss of facing stone after its chemical treatment have been specified. It has been proved that all chemical impregnations increases stone gloss; the lower the initial indices of the natural stone surface gloss are, the greater stone changes are observed. In turn, that is caused by the fact that each type of natural stone has its own gloss limit. The regularities of lightness changes and surface saturation of natural facing stone after chemical treatment have been defined. They indicate that all agents reduce lightness and increase saturation of the natural stone surface (except Impregnation agent 3). According to the identified regularities, it is possible to control quality indices of the natural stone surface with simultaneous provision of uniform colour shade of a stone-faced building. The main problem arising during the study of surfaces of natural stone samples by means of infrared spectroscopy was inhomogeneity of its mineral-chemical composition over the sample area. As a result, various spectra have been obtained that are difficult to identify without the prepared reference samples. Complete infrared spectra of the natural stone surfaces of Pokostivskyi granodiorite and Bukivskyi gabbro. Both Pokostivskyi granodiorite and Bukivskyi gabbro have different infrared spectra within the analyzed range of wavelengths that can be explained by the difference in mineralogical composition of both natural stone types.

      Originality. A large number of physical-mechanical parameters were analyzed, including a mathematical model, with which the slope geometry was calculated using the design profiles and 9 methods. This has given satisfactory results based on Eurocode EC-7 which can be implemented in the field.

      Practical implications. To analyze the numerical and analytical methods for the design slope geometry, geotechnical Eurocodes were used according to two standards: Eurocode EC7-1 for geotechnical designs and Eurocode EC7-2 for field verification. They were tested on two factors: Category of terrain and Category of objects (excavator), to remove the coal cover using technology in compliance with the conditions in the field, such as the presence of surface water, underground waters and tectonics. This whole analysis is time consuming, so a safety factor has been determined based on the numerical analysis data.

      Keywords: geomechanical parameters, geotechnical safety, Eurocode, coal mining

      REFERENCES

1. Krasniqi, I. (2020). Report on the production of electricity in Kosovo. Pristina, Kosovo: Academy of Sciences and Arts of Kosovo. Retrieved from: https://ashak.org/raporti-per-prodhimin-e-energjise-elektrike-ne-kosove
2. Mining strategy of the Republic of Kosovo for the period 2010-2025. (2011). Pristina, Kosovo: Ministry of Economic Development.
3. Ahmeti, H., Ahmeti, A., & Behrami, R. (2022). The impact of coal quality on reduction of environmental pollution researched through statistical analysis. Civil Engineering Journal, 8(08), 1596-1605. https://doi.org/10.28991/CEJ-2022-08-08-05
4. Kadriu, G., Krasniqi, A., & Ahmeti, H. (2017). Elaborati gjeologo-gjeomekanike. Prishtina, Kosovo: Institute INKOS Kastriot.
5. Geological-geomechanical drilling. (2010). Prishtina, Kosovo: Institute INKOS Kastriot-Obiliq.
6. Elezaj, Z., & Kodra, A. (2008). Gjeologjia e Kosovës. Prishtinë, Kosovo.
7. Karamata, S. (2006). The geological development of the Balkan Peninsula related to the approach, collision and compression of Gondwanan and Eurasian units. Geological Society, London, Special Publications, 260(1), 155-178. https://doi.org/10.1144/GSL.SP.2006.260.01.07
8. Dips. (2022). Graphical and statistical analysis of orientation data. Retrieved from: https://www.rocscience.com/software/dips
9. Surfer V21. (2022). User’s guide statistics. Retrieved from: https://www.goldensoftware.com/products/surfer
10. Ahmeti, H., Behrami, R., Hetemi, I., & Qorri, A. (2023). Formation of the geometry of the side slopes from the geotechnical aspect for the recultivation of the degraded area from coal mining. Journal of Ecological Engineering, 24(1), 195-204. https://doi.org/10.12911/22998993/156001
11. Das, B.M., & Sobhan, K. (2022). Principles of geotechnical engineering. Stamford, United States: Global Engineering, 766 p.
12. Frikha, W., Varaksin, S., & Viana da Fonseca, A. (2018). Soil testing, soil stability and ground improvement. Sustainable Civil Infrastructures. Cham, Switzerland: Springer, 251 p. https://doi.org/10.1007/978-3-319-61902-6
13. Hamad, J.T., & Almadhoun, Y.M. (2017). Soil mechanics laboratory manual. Lectures Notes. Retrieved from: http://site.iugaza.edu.ps/ymadhoun/teaching/soil-mechanics-laboratory-eciv3151/
14. Smith, I. (2014). Smith’s elements of soil mechanics. London, United Kingdom: Jonh Wiley & Sons, 176 p. https://doi.org/10.4324/9781315846484
15. Budhu, M. (2010). Soil mechanics and foundations. Hoboken, United States: Jonh Wiley & Sons, 784 p.
16. Anderson, R.D., Sweeney, J.D., & Williams-Rochester, A.T. (2003). Statistics for business and economics. Boston, United States: Thomson Learning, 1122 p.
17. Heumann, C., Schomaker, M., & Shalabh. (2016). Introduction to statistics and data analysis. Cham, Switzerland: Springer, 456 p. https://doi.org/10.1007/978-3-319-46162-5
18. Heiberger, R.M., & Holland, B. (2009). Statistical analysis and data display. New York, United States: Springer, 909 p. https://doi.org/10.1007/978-1-4939-2122-5
19. James, G., Witten, D., Hastie, T., & Tibshirani, R. (2021). An introduction to statistical learning. Springer Texts in Statistics, 15-57. https://doi.org/10.1007/978-1-0716-1418-1
20. Buß, J. (2022). Slope stability analysis and analysis of soil nailing and reinforced soil walls to DIN 4084 and EC 7. Steinfeld, Germany: Civilserve GmbH, 181 p.
21. Slide2. Slope stability. (2022). Verification manual. Toronto, Canada: Rocscience Inc.
22. SLOPE/W & SLOPE 3D. (2022). GeoStudio. Retrieved from: https://www.geoslope.com/products/slope-w
23. Ahmeti, H., Behrami, R., & Qorri, A. (2022). Re-cultivation of the area from the ecological aspect where limestone has been exploited in Pasomë village. Ecological Engineering & Environmental Technology, 23(6), 195-203. https://doi.org/10.12912/27197050/152957
24. Li, Q., Guo, J., Wang, F., & Song, Z. (2021). Monitoring the characteristics of ecological cumulative effect due to mining disturbance utilizing remote sensing. Remote Sensing, 13(24), 5034.
25. Doney, B.C., Blackley, D., Hale, J.M., Halldin, C., Kurth, L., Syamlal, G., & Laney, A.S. (2019). Respirable coal mine dust at surface mines, United States, 1982-2017. American Journal of Industrial Medicine, 63(3), 232-239. https://doi.org/10.1002/ajim.23074
26. Li, S., You, M., Li, D., & Liu, J. (2022). Identifying coal mine safety production risk factors by employing text mining and Bayesian network techniques. Process Safety and Environmental Protection, (162), 1067-1081. https://doi.org/10.1016/j.psep.2022.04.054
27. Balaj, N., Rizani, H., Kamberi, N., & Haxhinasto, L. (2022). The effect of rootstock on vegetative development and flower production in modern garden roses (Rosa canina L.). Bulgarian Journal of Agricultural Science, 28(3), 395-400.