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Abstract

Entries in steeply pitching seams have a more complex stress environment than those in flat seams. This study targets techniques for maintaining the surrounding rock mass stability of entries in steep seams through a case study of a steep-seam entry at a mine in southern China. An in-depth study of the deformation and instability mechanisms of the entry is conducted, employing field measurement, physical simulation experiment, numerical simulation, and theoretical analysis. The study results show that the surrounding rock mass of the entry is characterised by asymmetrical stress distribution, deformation, and failure. Specifically, 1) the entry deformation is characterised by a pattern of floor heaving and roof subsidence; 2) broken rock zones in the two entry walls are larger than those in the roof and floor, and the broken rock zone in the seam-floor side wall is larger than that in the seam-roof side wall; 3) rock bolts in the middle-bottom part of the seam-floor side wall of the entry are prone to failure due to tensile stress; and 4) rock bolts in the seam-roof side wall experience relatively even load and relatively small tensile stress. Through analysis, disturbances were found to occur in both temporal and spatial dimensions. Specifically, in the initial mining stage, the asymmetrical rock structure and stress distribution cause entry deformation and instability; during multiple-seam multiple-panel mining operations, a wedge-shaped rock mass and a quasi-arc cut rock stratum formed in the mining space may cause subsidence in the seam-floor side wall of the entry and inter-stratum transpression, deformation, and instability of the entry roof and floor. The principles for controlling the stability of the surrounding rock mass of the entry are proposed. In addition, an improved asymmetrical coupled support structure design for the entry is proposed to demonstrate the effective control of entry deformation.

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Authors and Affiliations

Panshi Xie
Yongping Wu
ORCID: ORCID
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Abstract

The deformation and failure law of stope roofs is more complicated than horizontal coal seams affected by the angle of the coal seam during the mining process of steeply dipping coal seams. This study focused on and analysed the working face of a 2130 coal mine with steep dipping and large mining height. Through the use of numerical calculation, theoretical analysis, physical similar material simulation experiments, and field monitoring, the distribution characteristics of roof stress, as well as the threedimensional caving migration and filling law, in large mining height working faces under the dip angle effect was investigated. The influence mechanism of the dip angle change on the roof stability of large mining heights was investigated. The results revealed that the roof stress was asymmetrically distributed along the inclination under the action of the dip angle, which resulted in roof deformation asymmetry. With the increase in the dip angle, the rolling and sliding characteristics of roof-broken rock blocks were more obvious. The length of the gangue support area increased, the unbalanced constraint effect of the filling gangue on the roof along the dip and strike was enhanced, and the height of the caving zone decreased. The stability of the roof in the lower inclined area of the working face was enhanced, the failure range of the roof migrated upward, and the damage degree of the roof in the middle and upper areas increased. Furthermore, cross-layer, large-scale, and asymmetric spatial ladder rock structures formed easily. The broken main roof formed an anti-dip pile structure, and sliding and deformation instability occurred, which resulted in impact pressure. This phenomenon resulted in the dumping and sliding of the support. The ‘support-surrounding rock’ system was prone to dynamic instability and caused disasters in the surrounding rock. The field measurement results verified the report and provided critical theoretical support for field engineering in practice.
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Authors and Affiliations

Panshi Xie
1 2
Baofa Huang
1 2
Yongping Wu
1 2
ORCID: ORCID
Shenghu Luo
2 3
ORCID: ORCID
Tong Wang
1 2
ORCID: ORCID
Zhuangzhuang Yan
1 2
Jianjie Chen
4

  1. Xi’an University of Science and Technology, School of Energy Engineering, Xi’an 710054, China
  2. Xi’an University of Science and Technology, Key Laboratory of Western Mine Exploitation and Hazard Prevention Ministry of Educat ion, Xi’an 710054, China
  3. Xi’an University of Science and Technology, Department of Mechanics, Xi’an, 710054, China
  4. Xinjiang Coking Coal Group Corporat ion Limited, Xinjiang 830025, China
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Abstract

Stability control of the roof is the key to safe and efficient mining of the longwall working face for a steeply dipping coal seam. In this study, a comprehensive analysis was performed on the roof destruction, migration, and filling characteristics of a steeply dipping longwall working face in an actual coalmine. Elastic foundation theory was used to construct a roof mechanics model; the effect of the coal seam inclination angle on the asymmetric deformation and failure of the roof under the constraint of an unbalanced gangue filling was considered. According to the model, increasing the coal seam angle, thickness of the immediate roof, and length of the working face as well as decreasing the thickness of the coal seam can increase the length of the contact area formed by the caving gangue in the lower area of the slope. Changes to the length of the contact area affect the forces and boundary conditions of the main roof. Increasing the coal seam angle reduces the deformation of the main roof, and the position of peak deflection migrates from the middle of the working face to the upper middle. Meanwhile, the position of the peak rotation angle migrates from the lower area of the working face to the upper area. The peak bending moment decreases continuously, and its position migrates from the headgate T-junction to the tailgate T-junction and then the middle of the working face. Field test results verified the rationality of the mechanics model. These findings reveal the effect of the inclination coal seam angle on roof deformation and failure and provide theoretical guidance for engineering practice.
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Bibliography

[1] Y.P. Wu, D.F Yun, P.S. Xie et al., Progress, practice and scientific issues in steeply dipping coal seams fullymechanized mining. J. China Coal Soc. 45 (01):24-34 (2020) (in Chinese).
[2]. Y.P. Wu, B.S. Hu, D Lang et al., Risk assessment approach for rockfall hazards in steeply dipping coal seams. Int. J. Rock Mech. Min. Sci. 138, 104626 (2021). doi: 10.1016/j.ijrmms.2021.104626
[3] D .Y. Zhu, W.L. Gong, Y. Su et al., Application of High-Strength Lightweight Concrete in Gob-Side Entry Retaining in Inclined Coal Seam. Advances in Materials Science and Engineering (2020). doi: 10.1155/2020/8167038
[4] H .W. Wang, Y.P. Wu, J.Q. Jiao et al., Stability Mechanism and Control Technology for Fully Mechanized Caving Mining of Steeply Inclined Extra-Thick Seams with Variable Angles. Mining, Metall. Explor. (2020). doi: 10.1007/ s42461-020-00360-0
[5] R .A. Frumkin, Predicting rock behaviour in steep seam faces (in Russian). International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts 20 (1), A12-A13 (1983). doi: 10.1016/0148-9062(83)91717-5
[6] A. Ladenko, Improvements in working steep seams. International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts 11 (12), 247. (1974). doi: 10.1016/0148-9062(74)92108-1
[7] Z. Rak, J. Stasica, Z. Burtan et al., Technical aspects of mining rate improvement in steeply inclined coal seams: A case study. Resources 9 (12), 1-16 (2020). doi: 10.3390/resources9120138
[8] H .S. Tu, S.H. Tu, C. Zhang et al., Characteristics of the Roof Behaviours and mine pressure manifestations during the mining of steep coal seam. Arch. Min. Sci. 62 (4), 871-890 (2020).
[9] P .S. Xie, Y.P. Wu, Deformation and failure mechanisms and support structure technologies for goaf-side entries in steep multiple seam mining disturbances. Arch. Min. Sci. 64 (3), 561-574 (2019). doi: 10.24425/ams.2019.129369
[10] Z.Y.Wang, L.M. Dou, J. He et al., Experimental investigation for dynamic instability of coal-rock masses in horizontal section mining of steeply inclined coal seams. Arabian Journal of Geosciences 13, 15 (2020). doi: 10.1007/ s12517-020-05753-5
[11] P .S. Xie, Y. Luo, Y.P. Wu et al., Roof Deformation Associated with Mining of Two Panels in Steeply Dipping Coal Seam Using Subsurface Subsidence Prediction Model and Physical Simulation Experiment. Mining, Metall. Explor. 37 (2), 581-591 (2020). doi: 10.1007/s42461-019-00156-x
[12] X.P. Lai, H. Sun, P.F. Shan et al., Structure instability forecasting and analysis of giant rock pillars in steeply dipping thick coal seams. Int. J. Miner. Metall. Mater. 22 (12), 1233-1244 (2015). doi: 10.1007/s12613-015-1190-z
[13] Y.P. Wu, B.S. Hu, P.S. Xie, A New Experimental System for Quantifying the Multidimensional Loads on an on-Site Hydraulic Support in Steeply Dipping Seam Mining. Exp. Tech. 43 (5), 571-585 (2019). doi: 10.1007/s40799-019- 00304-4
[14] Y.D. Zhang, J.Y. Cheng, X.X. Wang et al., Thin plate model analysis on roof break of up-dip or down-dip mining stope. J. Min. Saf. Eng. 27 (4), 487 (2010) (in Chinese).
[15] J.R. Cao, L.M. Dou, G.A. Zhu et al., Mechanisms of Rock Burst in Horizontal Section Mining of a Steeply Inclined Extra-Thick Coal Seam and Prevention Technology. Energies 13 (22), 6043 (2020). doi: 10.3390/en13226043
[16] H .W. Wang, Y.P. Wu, M. Liu et al., Roof-breaking mechanism and stress-evolution characteristics in partial backfill mining of steeply inclined seams. Geomatics, Natural Hazards and Risk 11 (1), 2006-2035 (2020). doi: 10.1080/1 9475705.2020.1823491
[17] S.R. Islavath, D. Deb, H. Kumar, Numerical analysis of a longwall mining cycle and development of a composite longwall index. Int. J. Rock Mech. Min. Sci. 89, 43-54 (2016).
[18] H . Basarir, O.I. Ferid, O. Aydin, Prediction of the stresses around main and tail gates during top coal caving by 3D numerical analysis. Int. J. Rock Mech. Min. Sci. 76, 88-97 (2015). doi: 10.1016/j.ijrmms.2015.03.001
[19] J.A. Wang, J.L. Jiao, Criteria of support stability in mining of steeply inclined thick coal seam. Int. J. Rock Mech. Min. Sci. 82, 22-35 (2016). doi: 10.1016/j.ijrmms.2015.11.008
[20] W.Y. Lv, Y.P. Wu, M. Liu et al., Migration law of the roof of a composited backfilling longwall face in a steeply dipping coal seam. Minerals 9 (3) (2019). doi: 10.3390/min9030188
[21] C.F. Huang, Q. Li, S.G.Tian, Research on prediction of residual deformation in goaf of steeply inclined extra- thick coal seam. PLoS ONE 15, 1-14 (2020). doi: 10.1371/journal.pone.0240428
[22] Y.C. Yin, J.C. Zou, Y.B. Zhang et al., Experimental study of the movement of backfilling gangues for goaf in steeply inclined coal seams. Arabian Journal of Geosciences 11 (12) (2018). doi: 10.1007/s12517-018-3686-0
[23] G .S.P Singh, U.K. Singh, Prediction of caving behavior of strata and optimum rating of hydraulic powered support for longwall workings. Int. J. Rock Mech. Min. Sci. 47, 1-16 (2010).
[24] P .S. Xie, Y.Y. Zhang, S.H. Luo et al., Instability Mechanism of a Multi-Layer Gangue Roof and Determination of Support Resistance Under Inclination and Gravity. Mining, Metall. Explor. 37 (5), 1487-1498 (2020). doi: 10.1007/ s42461-020-00252-3
[25] G .J. Wu, W.D. Chen, S.P. Jia et al., Deformation characteristics of a roadway in steeply inclined formations and its improved support. Int. J. Rock Mech. Min. Sci. 130, 104324 (2020). doi: 10.1016/j.ijrmms.2020.104324
[26] Y.Q. Long, Numerical computation of beam on elastic foundation. People’s Education Press, Beijing (1981).

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Authors and Affiliations

Shenghu Luo
1
ORCID: ORCID
Tong Wang
2
ORCID: ORCID
Yongping Wu
2
ORCID: ORCID
Jingyu Huangfu
2
ORCID: ORCID
Huatao Zhao
3
ORCID: ORCID

  1. Xi’an University of Science and Technology, Department of Mechanics, China
  2. Xi’an University of Science and Technology, School of Energy Engineering, China
  3. Shandong Mining Machinery Group Co., Ltd. China

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