A novel control method of automatically formed roadway by roof cutting and confined concrete column in extremely close-distance coal seam

Abstract

Under the influence of the upper coal pillars and dynamic pressure of coal mining, the roadway of the lower coal seam is prone to large deformation failure. In this paper, a novel control method and key technologies of automatically formed roadway (AFR) by roof cutting and confined concrete column in extremely close-distance coal seam are proposed. Furthermore, a numerical model is established to analyze the structure characteristics of overlying roof strata. Based on numerical results, the roof structure model of “voussoir beam of upper layer + short cantilever beam of lower layer” of this method is proposed. What’s more, the calculation equation of the roof bending moment and evaluation indexes is established, and the influence of different factors on roof stability control of AFR is studied. Finally, a field test is conducted to verify the effectiveness of this novel method. Field results were as follows: 1) The maximum and average support stress of working face obviously decreased; 2) The confined concrete column can provide high-strength support in dynamic influence zone; 3) The maximum deformation of AFR safety requirement can be met. This study can provide effective guidance for the application of this method in extremely close-distance coal seam.

Keywords

extremely close-distance coal seam / automatically formed roadway (AFR) / confined concrete column / numerical simulation / roof structure model / field test

References

[1] Tulu I B, Esterhuizen G S, Klemetti T, et al. . A case study of multi-seam coal mine entry stability analysis with strength reduction method [J]. International Journal of Mining Science and Technology, 2016, 26(2): 193-198.

[2] Li Y, Ren Y-q, Peng S S, et al. . Measurement of overburden failure zones in close-multiple coal seams mining [J]. International Journal of Mining Science and Technology, 2021, 31(1): 43-50.

[3] Liu H-y, Zuo J-p, Zhang C-w, et al. . Asymmetric deformation mechanism and control technology of roadway under room-pillar group in Huasheng coal mine [J]. Journal of Central South University, 2023, 30(7): 2284-2301.

[4] Louloudis G, Roumpos C, Theofilogiannakos K, et al. . Multi-seam coal deposit modeling via principal component analysis & GIS [J]. Minerals, 2019, 9(9): 532.

[5] Xing H-l, Han Z-ting. Caving-induced fault reactivation behaviour and its effects on mining safety with a multiple seam context [J]. Acta Geotechnica, 2020, 15(12): 3461-3481.

[6] Ning J-g, Wang J, Tan Y-l, et al. . Mechanical mechanism of overlying strata breaking and development of fractured zone during close-distance coal seam group mining [J]. International Journal of Mining Science and Technology, 2020, 30(2): 207-215.

[7] Prakash A, Kumar N, Kumbhakar D, et al. . A safe depillaring design for shallow depth of cover with influence of surface ground movements: A study in Jharia Coalfield [J]. Arabian Journal of Geosciences, 2018, 11(8): 164.

[8] Szott W, Słota-Valim M, Gołąbek A, et al. . Numerical studies of improved methane drainage technologies by stimulating coal seams in multi-seam mining layouts [J]. International Journal of Rock Mechanics and Mining Sciences, 2018, 108: 157-168.

[9] Zhang J-w, Liu C, Li Y-l, et al. . Study on the surrounding rock structure of stagger layout roadway and its pressure release as well as deformation yielding mechanism [J]. Journal of China Coal Society, 2018, 43(8): 2133-2143

[10] Zhang P, Tulu B, Sears M, et al. . Geotechnical considerations for concurrent pillar recovery in close-distance multiple seams [J]. International Journal of Mining Science and Technology, 2018, 28(1): 21-27.

[11] Ghabraie B, Ren G, Smith J V. Characterising the multi-seam subsidence due to varying mining configuration, insights from physical modelling [J]. International Journal of Rock Mechanics and Mining Sciences, 2017, 93: 269-279.

[12] Ghabraie B, Ren G, Barbato J, et al. . A predictive methodology for multi-seam mining induced subsidence [J]. International Journal of Rock Mechanics and Mining Sciences, 2017, 93: 280-294.

[13] Adhikary D, Khanal M, Jayasundara C, et al. . Deficiencies in 2D simulation: A comparative study of 2D versus 3D simulation of multi-seam longwall mining [J]. Rock Mechanics and Rock Engineering, 2016, 49(6): 2181-2185.

[14] Ghosh N, Agrawal H, Singh S K, et al. . Optimum chain pillar design at the deepest multi-seam longwall workings in India [J]. Mining, Metallurgy & Exploration, 2020, 37(2): 651-664.

[15] Chen D-d, Wu Y-y, Xie S-r, et al. . Reasonable location of stopping line in close-distance underlying coal seam and partition support of large cross-section roadway [J]. International Journal of Coal Science & Technology, 2022, 9(1): 55.

[16] Yin S-f, Zheng X-j, Wang E, et al. . Nonuniform failure and differential pressure relief technology of roadway under irregular goafs in deep close-distance coal seams [J]. Scientific Reports, 2023, 13(1): 18527.

[17] Shang Y-q, Kong D-z, Pu S-j, et al. . Study on failure characteristics and control technology of roadway surrounding rock under repeated mining in close-distance coal seam [J]. Mathematics, 2022, 10(13): 2166.

[18] Cao Y-h, Li Y-ting. Deformation control of surrounding rocks of mining roadway in deep and close lower coal seam [J]. Coal Science and Technology, 2021, 49(9): 76-81(in Chinese)

[19] Wang Q, Xu S, Jiang B, et al. . Research progress of confined concrete support theory and technology for underground engineering [J]. Journal of the China Coal Society, 2020, 45(8): 2760-2776(in Chinese)

[20] Wei J-g, Xie Z-t, Zhang W, et al. . Experimental study on circular steel tube-confined reinforced UHPC columns under axial loading [J]. Engineering Structures, 2021, 230: 111599.

[21] He M-c, Wang Q. Rock dynamics in deep mining [J]. International Journal of Mining Science and Technology, 2023, 33(9): 1065-1082.

[22] He M-c, Wang Q, Wu Q-ying. Innovation and future of mining rock mechanics [J]. Journal of Rock Mechanics and Geotechnical Engineering, 2021, 13(1): 1-21.

[23] Wang Q, He M-c, Li S-c, et al. . Comparative study of model tests on automatically formed roadway and gob-side entry driving in deep coal mines [J]. International Journal of Mining Science and Technology, 2021, 31(4): 591-601.

[24] Guo Z-b, Li W-t, He M-c, et al. . Model test on failure mechanisms of deep high-stress soft rock roadways based on excavation compensation method [J]. Engineering Failure Analysis, 2024, 160: 108161.

[25] Xue H-j, Jiang B, He M-c, et al. . Mechanism and validation of pressure relief and energy reduction of automatically formed roadway by roof cutting in deep coal mines [J]. Bulletin of Engineering Geology and the Environment, 2025, 84(2): 77.

[26] Wang Q, Jiang Z-h, Jiang B, et al. . Research on an automatic roadway formation method in deep mining areas by roof cutting with high-strength bolt-grouting [J]. International Journal of Rock Mechanics and Mining Sciences, 2020, 128: 104264.

[27] Wang Q, Qin Q, Jiang B, et al. . Geomechanics model test research on automatically formed roadway by roof cutting and pressure releasing [J]. International Journal of Rock Mechanics and Mining Sciences, 2020, 135: 104506.

[28] Xue H-j, Wang Q, Jiang B, et al. . Study on the method of pressure relief by roof cutting and absorbing energy in deep coal mines [J]. Bulletin of Engineering Geology and the Environment, 2023, 82(8): 298.

[29] Gao Y-b, Yang J, He M-c, et al. . Mechanism and control techniques for gangue rib deformations in gob-side entry retaining formed by roof fracturing in thick coal seams [J]. Chinese Journal of Rock Mechanics and Engineering, 2017, 36(10): 2492-2502(in Chinese)

[30] Wang H-s, Wang J, Elmo D, et al. . Ground response mechanism of entries and control methods induced by hard roof in longwall top coal caving panel [J]. Engineering Failure Analysis, 2023, 144: 106940.

[31] Gao H-n, Gao Y-b, Qi J-c, et al. . Study on surrounding rock deformation and gas control of entry automatically formed by roof cutting in high-gas coal seam [J]. Energy Exploration & Exploitation, 2023, 41(5): 1559-1575.

[32] Wang Q, Jiang B, Xu S, et al. . Roof-cutting and energy-absorbing method for dynamic disaster control in deep coal mine [J]. International Journal of Rock Mechanics and Mining Sciences, 2022, 158: 105186.

[33] He M-c, Ren S-l, Guo L-j, et al. . Experimental study on influence of host rock strength on shear performance of micro-NPR steel bolted rock joints [J]. International Journal of Rock Mechanics and Mining Sciences, 2022, 159: 105236.

[34] He M-c, Wang Q. Excavation compensation method and key technology for surrounding rock control [J]. Engineering Geology, 2022, 307: 106784.

[35] Qian M-g, Miao X-x, He F-lian. Key block analysis of voussoir beam structure in stope [J]. Journal of China Coal Society, 1994, 19(6): 557-562(in Chinese)

RIGHTS & PERMISSIONS

Central South University