Abstract
The overburden rock strata fractures and collapses as the extraction of a longwall panel. Knowledge of the extents and characteristics of the fractured zone is important to evaluating many mining-induced issues including abutment pressure relief, methane production, and ground subsidence prediction. In this study, a physical model was initially created to produce the process of longwall mining with great attention focused on the caving and fracturing process of the overburden strata. A numerical model was then created according to the geological and geotechnical conditions of the physical model. Both the physical and numerical model successfully captured periodic weighting as the longwall face advances. It is found that periodic weighting does not just involve the local immediate and main roof that composes a cantilever beam right behind the longwall face, it may also involve the rupture of a rock bridge in the overburden strata above the fractured zone. The rock bridge forms and ruptures periodically as longwall mining proceeds. The permeability of a given region in the fractured zone can be evaluated by measuring the area of the voids and fractures within the region. The permeability increases as fracturing and collapse of rock mass within the region and then decreases as the collapsed rock mass compacts. The greater the horizontal-to-vertical stress ratio, the lower the maximum permeability. The more competent the main roof, the lower the maximum permeability.
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References
Bandis SC, Lumsden AC, Barton NR (1983) Fundamentals of rock joint deformation. Int J Rock Mech Min Sci Geomech Abstr 20:249–268. https://doi.org/10.1016/0148-9062(83)90595-8
Das SK (2000) Observations and classification of roof strata behaviour over longwall coal mining panels in India. Int J Rock Mech Min Sci 37:585–597. https://doi.org/10.1016/S1365-1609(99)00123-9
Diederichs MS, Kaiser PK (1999) Stability of large excavations in laminated hard rock masses: the voussoir analogue revisited. Int J Rock Mech Min Sci 36:97–117. https://doi.org/10.1016/S0148-9062(98)00180-6
Dougherty HN, ÖzgenKaracan C (2011) A new methane control and prediction software suite for longwall mines. Comput Geosci 37:1490–1500. https://doi.org/10.1016/j.cageo.2010.09.003
Elmo D (2006) Evaluation of a hybrid FEM/DEM approach for determination of rock mass strength using a combination of discontinuity mapping and fracture mechanics modelling, with particular emphasis on modelling of jointed pillars. PhD thesis, University of Exeter
Ghabraie B, Ren G, Zhang X, Smith J (2015) Physical modelling of subsidence from sequential extraction of partially overlapping longwall panels and study of substrata movement characteristics. Int J Coal Geol 140:71–83. https://doi.org/10.1016/j.coal.2015.01.004
Ghabraie B, Ren G (2016) Mechanism and prediction of ground surface subsidence due to multiple-seam longwall mining. In: Proceeding of the 35th international conference on ground control in mining, Morgantown, pp 1–7
Karacan CÖ, Esterhuizen GS, Schatzel SJ, Diamond WP (2007) Reservoir simulation-based modeling for characterizing longwall methane emissions and gob gas venthole production. Int J Coal Geol 71:225–245. https://doi.org/10.1016/j.coal.2006.08.003
Karacan CÖ, Olea RA, Goodman G (2012) Geostatistical modeling of the gas emission zone and its in-place gas content for Pittsburgh-seam mines using sequential Gaussian simulation. Int J Coal Geol 90–91:50–71. https://doi.org/10.1016/j.coal.2011.10.010
Kendorski FS (1993) Effect of high-extraction coal mining on surface and ground waters. In: Proceedings of the 12th conference on ground control in mining. West Virginia University, Margantown
Kratzsch IH (1986) Mining subsidence engineering. Environ Geol Water Sci 8:133–136. https://doi.org/10.1007/BF02509900
Le TD, Oh J, Hebblewhite B et al (2018) A discontinuum modelling approach for investigation of longwall top coal caving mechanisms. Int J Rock Mech Min Sci 106:84–95. https://doi.org/10.1016/j.ijrmms.2018.04.025
Lunarzewski L (1998) Gas emission prediction and recovery in underground coal mines. Int J Coal Geol 35:117–145. https://doi.org/10.1016/S0166-5162(97)00007-4
Mandl G (2005) Rock joints—the mechanical genesis | Georg Mandl | Springer. Springer, Berlin
Mills KW, Puller J, Salisbury O (2015) Measurements of horizontal Shear movements ahead of longwall mining and implications for overburden behaviour. In: Proceeding of the 34th international conference on ground control in mining, Morgantown, pp 1–6
Moore TA (2012) Coalbed methane: a review. Int J Coal Geol 101:36–81. https://doi.org/10.1016/j.coal.2012.05.011
Palchik V (2002) Influence of physical characteristics of weak rock mass on height of caved zone over abandoned subsurface coal mines. Environ Geol 42:92–101. https://doi.org/10.1007/s00254-002-0542-y
Palchik V (2003) Formation of fractured zones in overburden due to longwall mining. Environ Geol 44:28–38. https://doi.org/10.1007/s00254-002-0732-7
Palchik V (2010) Experimental investigation of apertures of mining-induced horizontal fractures, pp 502–508
Peng S (1986) Coal mine ground control (2nd edition), 2nd edn. Wiley, New York
Pine RJ, Coggan JS, Flynn ZN, Elmo D (2006) The eevelopment of a new numerical modelling approach for naturally fractured rock masses. Rock Mech Rock Eng 39:395–419. https://doi.org/10.1007/s00603-006-0083-x
Rockfield (2018) ELFEN-advanced finite element/discrete element. Version 4.7.4. Rockfield Software Ltd., Swansea. https://www.rockfieldglobal.com/software/advanced-finite-element/
Schindelin J, Arganda-Carreras I, Frise E et al (2012) Fiji: an open-source platform for biological-image analysis. Nat Methods 9:676–682. https://doi.org/10.1038/nmeth.2019
Singh TN, Farmer IW (1985) A physical model of an underground coal mine prototype. Int J Min Eng 3:319–326. https://doi.org/10.1007/BF00880842
Song G, Yang S (2015) Investigation into strata behaviour and fractured zone height in a high-seam longwall coal mine. J South Afr Inst Min Metall 115:781–788. https://doi.org/10.17159/2411-9717/2015/V115N8A16
Wang C, Zhang C, Zhao X et al (2018) Dynamic structural evolution of overlying strata during shallow coal seam longwall mining. Int J Rock Mech Min Sci 103:20–32. https://doi.org/10.1016/j.ijrmms.2018.01.014
Whittaker BN, Gaskell P, Reddish DJ (1990) Subsurface ground strain and fracture development associated with longwall mining. Min Sci Technol 10:71–80. https://doi.org/10.1016/0167-9031(90)90864-O
Xu J, Xuan D, Zhu W et al (2015) Study and application of coal mining with partial backfilling. J China Coal Soc 40:1303–1312
Yu B, Zhao J, Kuang T, Meng X (2015) In situ investigations into overburden failures of a super-thick coal seam for longwall top coal caving. Int J Rock Mech Min Sci 78:155–162. https://doi.org/10.1016/j.ijrmms.2015.05.009
Zou DHS, Yu C, Xian X (1999) Dynamic nature of coal permeability ahead of a longwall face. Int J Rock Mech Min Sci 36:693–699. https://doi.org/10.1016/S0148-9062(99)00034-0
Acknowledgements
This work has been supported by the Major National Science and Technology Projects of China (Grant no. 2016ZX05045003-006). The author would like to thank their colleagues for their assistance during the physical modeling.
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Gao, F., Li, J., Lou, J. et al. Understanding the evolution of mining-induced fractures using physical and numerical modeling. Environ Earth Sci 81, 22 (2022). https://doi.org/10.1007/s12665-021-10141-7
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DOI: https://doi.org/10.1007/s12665-021-10141-7