Abstract
Influenced by mining activities in adjacent coal seams, stresses on rocks surrounding roadway were redistributed, and the roadways in lower coal seam were subjected to the asymmetrical roof falling and roof sagging. Considering stresses effect on the plastic zone around the roadway, numerical models were carried out by FLAC to investigate plastic zone with respect to stress ratio and direction of stresses. The relationship between the properties of surrounding rock and plastic zone boundary was also investigated by another numerical model and analytical study, whereby the tailgate stability of panel 30,501 in Tashan coal mine was implemented. It is shown that the rocks surrounding a roadway in the lower coal seam were subjected to unequal stresses, and the principal stress direction was deflected from the original direction. High stresses and big stress ratio can produce butterfly-shaped or X-shaped plastic zone. The direction of stresses was deflected, causing the plastic zone around the roadway to be transferred from the shoulder to the roof of the roadway. Consequently, asymmetrical stresses produce asymmetrical plastic zone. On this basis, the tailgate should be assigned conditions of the stresses and stress ratio at a low level. In this way, the tailgate was arranged at the position where the horizontal distance from the roadway in the lower seam to the centre line of the coal pillar in the upper seam (x) is 52.5 m, and was stable relatively.
Similar content being viewed by others
References
Brady BGH, Brown ET (1985) Rock mechanics for underground mining. George Allen & Unwin
Gao R, Yu B, Xia HC, Duan HF (2017) Reduction of stress acting on a thick, deep coal seam by protective-seam mining. Energies 10(8):1029. https://doi.org/10.3390/en10081209
Guo XF, Zhao ZQ, Gao X, Wu XY, Ma NJ (2018) Analytical solutions for characteristic radii of circular roadway surrounding rock plastic zone and their application. Intl J Min Sci Tech 29(02):263–272. https://doi.org/10.1016/j.ijmst.2018.10.002
Hauquin T, Deck O, Gunzburger Y (2016) Average vertical stress on irregular elastic pillars estimated by a function of the relative extraction ratio. Int J Rock Mech Min Sci 83:122–134. https://doi.org/10.1016/j.ijrmms.2015.12.004
Jaiswal A, Shrivastva BK (2009) Numerical simulation of coal pillar strength. Int J Rock Mech Min Sci 46(8):779–788. https://doi.org/10.1016/j.ijrmms.2008.11.003
Jiang LS, Sainoki A, Mitri HS, Ma NJ, Liu HT, Hao Z (2016) Influence of fracture-induced weakening on coal mine gateroad stability. Int J Rock Mech Min Sci 88:307–317. https://doi.org/10.1016/j.ijrmms.2016.04.017
Jiang LS, Kong P, Shu JM, Fan KG (2019a) Numerical analysis of support designs based on a case study of a longwall entry. Rock Mech Rock Eng 52:3373–3384. https://doi.org/10.1007/s00603-018-1728-2
Jiang LS, Wu QS, Wu QL, Wang P, Xue YC, Kong P, Gong B (2019b) Fracture failure analysis of hard and thick key layer and its dynamic response characteristics. Eng Fail Anal 98:118–130
Ju JF, Xu JL, Zhu WB (2015) Longwall chock sudden closure incident below coal pillar of adjacent upper mined coal seam under shallow cover in the Shendong coalfield. Int J Rock Mech Min Sci 77:192–201. https://doi.org/10.1016/j.ijrmms.2015.04.004
Kong P, Jiang LS, Shu JM, Sainoki A, Wang QB (2019) Effect of fracture heterogeneity on rock mass stability in a highly heterogeneous underground roadway. Rock Mech Rock Eng 52:4547–4564. https://doi.org/10.1007/s00603-019-01887-5
Liu XJ, Li XM, Pan WD (2016) Analysis on the floor stress distribution and roadway position in the close distance coal seams. Arab J Geosc 9:83–88. https://doi.org/10.1007/s12517-015-2035-9
Ma NJ, Hou CJ (1990) A research into plastic zone of surrounding strata of gateway effected by mining abutment stress, in The 31th U.S. Symposium on Rock Mechanics (USRMS), Golden, Colorado,18-20 June, American Rock Mechanics Association, US, 211–216
Poulsen BA (2010) Coal pillar load calculation by pressure arch theory and near field extraction ratio. Int J Rock Mech Min Sci 47(7):1158–1165. https://doi.org/10.1016/j.ijrmms.2010.06.011
Shen B, Barton N (1997) The disturbed zone around tunnels in jointed rock masses. Int J Rock Mech Min Sci 34(1):117–125. https://doi.org/10.1016/S1365-1609(97)80037-8
Wang JH, Yu B, Kang HP, Wang GF, Mao DB, Liang YT, Jiang PF (2015) Key technologies and equipment for a fully mechanized top-coal caving operation with a large mining height at ultra-thick coal seams. Int J Coal Sci Tech 2(2):97–161. https://doi.org/10.1007/s40789-015-0071-4
Wattimena RK, Kramadibrata S, Sidi ID, Azizi MA (2013) Developing coal pillar stability chart using logistic regression. Int J Rock Mech Min Sci 58:55–60. https://doi.org/10.1016/j.ijrmms.2012.09.004
Zhang HL, Cao JJ, Tu M (2013) Floor stress evolution laws and its effect on stability of floor roadway. Int J Min Sci Tech 23(5):631–636. https://doi.org/10.1016/j.ijmst.2013.08.002
Zhang GC, Liang SJ, Tan YL, Xie FX, Chen SJ, Jia HG (2018) Numerical modeling for longwall pillar design: a case study from a typical longwall panel in China. J Geophys Eng 15:121–134. https://doi.org/10.1088/1742-2140/aa9ca4
Zhao XG, Cai M (2010) Influence of plastic shear strain and confinement-dependent rock dilation on rock failure and displacement near an excavation boundary. Int J Rock Mech Min Sci 47(5):723–738. https://doi.org/10.1016/j.ijrmms.2010.04.003
Zhao J, Li GB (2016) Pressure-relief mining of the working face under the coal pillar in the close distance coal seams. Geotech Geol Eng 34(1):1067–1077. https://doi.org/10.1007/s10706-016-0027-5
Zhu CJ, Lin BQ (2015) Effect of igneous intrusions and normal faults on coalbed methane storage and migration in coal seams near the outcrop. Nat Hazards 77(1):17–38. https://doi.org/10.1007/s11069-014-1577-6
Acknowledgements
This research work was supported by The National Natural Science Foundation of China (Grant no. 51774288, 51434006 and 51704294) and the field measurement exercise was supported by Datong Energy Co., Ltd. The authors are grateful for their support.
Author information
Authors and Affiliations
Corresponding author
Additional information
Responsible Editor: Zeynal Abiddin Erguler
Rights and permissions
About this article
Cite this article
Liu, H., Qiao, B. & Ma, N. Stability analysis and design of roadways in adjacent seams: a case study from Tashan coal mine in China. Arab J Geosci 13, 308 (2020). https://doi.org/10.1007/s12517-020-05289-8
Received:
Accepted:
Published:
DOI: https://doi.org/10.1007/s12517-020-05289-8