Control technology for floor heave of Jurassic soft rock in the Erdos Basin of China: A case study

Abstract

The deformation of soft rock roadway caused by floor heave is a major challenge for coal mines in China western mining areas. To achieve security and stability of soft rock roadway, this work considered the headgate at panel 11505 of the Yushujing Coal Mine as background. First, based on the limit equilibrium method and slip line field theory, a model of floor heave was established, the mechanism of floor heave control was analyzed, and an optimized support method was proposed. Then, the displacement, stress and failure zones around the surrounding rock with the original and optimized support were studied by FLAC. Finally, the serviceability of the support method was verified by field application. The results showed that the main deformation form of soft rock roadway is floor heave, and 0.5 m is relatively reasonable thicknesses of the inverted arch. The extrusion failure zone and shear failure zone were mainly affected by tensile and shear failure, respectively. The modification of floor and the effective support are key points. The failure zone was consistent between numerical simulation and theoretical calculation. The maximum convergences of floor heave determined by numerical simulation and field measurement were 220 mm and 240 mm, respectively, which were reduced by 55% and 60% compared with the original support, and the convergence between sidewalls decreased considerably. The optimized support method controls the floor heave well.

Keywords

soft rock roadway / floor heave / mechanical model / control mechanism / optimized support

References

[1] ShenB-T. Coal mine roadway stability in soft rock: A case study [J]. Rock Mechanics and Rock Engineering, 2014, 47(6): 2225-2238

[2] JessuK V, KosteckiT R, SpearingA J S, et al. . Influence of varying bedding thickness of underclay on floor stability [J]. International Journal of Mining Science and Technology, 2017, 27(3): 517-523

[3] JiangL-S, SainokiA, MitriH S, et al. . Influence of fracture-induced weakening on coal mine gateroad stability [J]. International Journal of Rock Mechanics and Mining Sciences, 2016, 88: 307-317

[4] ShreedharanS, KulatilakeP H S W. Discontinuum—equivalent continuum analysis of the stability of tunnels in a deep coal mine using the distinct element method [J]. Rock Mechanics and Rock Engineering, 2016, 49(5): 1903-1922

[5] MoS, RamandiH L, OhJ, et al. . A new coal mine floor rating system and its application to assess the potential of floor heave [J]. International Journal of Rock Mechanics and Mining Sciences, 2020, 128: 104241

[6] HeM-C, YuanY, WangX-L, et al. . Control technology for large deformation of Mesozoic compound soft rock in Xinjiang and its application [J]. Chinese Journal of Rock Mechanics and Engineering, 2013, 32(3): 433-441

[7] TangS B, TangC A. Numerical studies on tunnel floor heave in swelling ground under humid conditions [J]. International Journal of Rock Mechanics and Mining Sciences, 2012, 55139-150

[8] BaiJ-B, LiW-F, WangX-Y, et al. . Mechanism of floor heave and control technology of roadway induced by mining [J]. Journal of Mining and Safety Engineering, 2011, 28(1): 1-5

[9] KangH-P, LuS-L. An analysis on the mechanism of roadway floor heave [J]. Chinese Journal of Rock Mechanics and Engineering, 1991, 4: 362-373

[10] WenZ-J, LuJ-Y, XiaoQ-H, et al. . Failure mechanism of floor heave and supporting technology of soft rock roadway [J]. Journal of China Coal Society, 2019, 44(7): 1991-1999

[11] YangS-Q, ChenM, JingH-W, et al. . A case study on large deformation failure mechanism of deep soft rock roadway in Xin’ an coal mine, China [J]. Engineering Geology, 2017, 217: 89-101

[12] LiL-P, ShangC-S, ChuK-W, et al. . Large-scale geo-mechanical model tests for stability assessment of super-large cross-section tunnel [J]. Tunnelling and Underground Space Technology, 2021, 109: 103756

[13] YuK-P, RenF-Y, PuscasuR, et al. . Optimization of combined support in soft-rock roadway [J]. Tunnelling and Underground Space Technology, 2020, 103103502

[14] MoS, SheffieldP, CorbettP, et al. . A numerical investigation into floor buckling mechanisms in underground coal mine roadways [J]. Tunnelling and Underground Space Technology, 2020, 103103497

[15] KangH P, LinJ, FanM J. Investigation on support pattern of a coal mine roadway within soft rocks—A case study [J]. International Journal of Coal Geology, 2015, 14031-40

[16] PerryK, BradleyJ, UnrugK, et al. . Mitigation of floor heave in west Kentucky coal mine [J]. International Journal of Mining Science and Technology, 2016, 26(3): 521-525

[17] SunX-M, ZhaoC-W, ZhangY, et al. . Physical model test and numerical simulation on the failure mechanism of the roadway in layered soft rocks [J]. International Journal of Mining Science and Technology, 2021, 31(2): 291-302

[18] WangH, ZhengP-Q, ZhaoW-J, et al. . Application of a combined supporting technology with U-shaped steel support and anchor-grouting to surrounding soft rock reinforcement in roadway [J]. Journal of Central South University, 2018, 25(5): 1240-1250

[19] WANG Yu-yang, LIU Yong, WANG Chen, et al. Optimization and application research of soft rock roadway support scheme based on AHP [J]. Journal of Mining and Strata Control Engineering, 2020(2): 36–44. (in Chinese)

[20] ZHANG Tian, WANG Yi-liang. Study on deformation evolution law and support technology of surrounding rock in multiple mining roadway [J]. Journal of Mining and Strata Control Engineering, 2020(2): 62–69. (in Chinese)

[21] MengQ-B, HanL-J, ZhangJ, et al. . Research and application of supporting technology in deep high stress fractured soft-rock roadway [J]. Journal of Central South University (Science and Technology), 2016, 47(11): 3861-3872

[22] JiaZ-Q, XieH-P, ZhangR, et al. . Acoustic emission characteristics and damage evolution of coal at different depths under triaxial compression [J]. Rock Mechanics and Rock Engineering, 2020, 53(5): 2063-2076

[23] WangX, WenZ-J, JiangY-J, et al. . Experimental study on mechanical and acoustic emission characteristics of rock-like material under non-uniformly distributed loads [J]. Rock Mechanics and Rock Engineering, 2018, 51(3): 729-745

[24] MoS, TutukK, SaydamS. Management of floor heave at Bulga Underground Operations_—A case study [J]. International Journal of Mining Science and Technology, 2019, 29(1): 73-78

[25] SekiS, KaiseS, MorisakiY, et al. . Model experiments for examining heaving phenomenon in tunnels [J]. Tunnelling and Underground Space Technology, 2008, 23(2): 128-138

[26] AlejanoL R, AlonsoE. Considerations of the dilatancy angle in rocks and rock masses [J]. International Journal of Rock Mechanics and Mining Sciences, 2005, 42(4): 481-507

[27] AggsonCoal mine floor heave in the Beckley coalbed, an analysis [R], 1978, United States, Denver Mining Research Center

[28] SmirnovA V, ZakharovV N, KharchenkoA V, et al. . Geomechanical model of floor swelling in coal mines [J]. Gornyi Zhurnal, 2017, 11: 33-36

[29] WuX-Y, JiangL-S, XuX-G, et al. . Numerical analysis of deformation and failure characteristics of deep roadway surrounding rock under static-dynamic coupling stress [J]. Journal of Central South University, 2021, 28(2): 543-555

[30] MengL-BStudy on the tunnel floor heave mechanism and remediation measures of south Lvliangshan tunnel [D], 2017, Shijiazhuang, Shijiazhuang Tiedao University

[31] YU Yuan-xiang, KE Da, WANG Jing-bin, et al. Discussion on determination method of the limit equilibrium zone width based on the deformation analysis of coal wall [J]. Journal of China Coal Society, 2019(11): 3340–3348. (in Chinese)

[32] AiT, WuS-Y, ZhangR, et al. . Changes in the structure and mechanical properties of a typical coal induced by water immersion [J]. International Journal of Rock Mechanics and Mining Sciences, 2021, 138104597

[33] ZhaoT-B, XingM-L, GuoW-Y, et al. . Anchoring effect and energy-absorbing support mechanism of large deformation bolt [J]. Journal of Central South University, 2021, 28(2): 572-581

[34] HeM-C. Mechanics mechanism of soft rock deformation and supporting countermeasures in coal mine [J]. Hydrogeology Engineering Geology, 1997, 24(2): 12-16

[35] ShimamotoK, YashiroK, KojimaY, et al. . Study on floor heave and its countermeasures in mountain tunnels with consideration of the influence of construction [J]. Journal of Japan Society of Civil Engineers, Ser F1 (Tunnel Engineering), 2013, 69(2): 105-120

[36] LiL, WenZ-J. Research of optimal floor heave control technology and its engineering application in soft rock roadway [J]. Journal of China Coal Society, 2021, 46(4): 1242-1252

[37] WangW-J, FengT. Study on mechanism of reinforcing sides to control floor heave of extraction opening [J]. Chinese Journal of Rock Mechanics and Engineering, 2005, 24(05): 808-811

[38] DiamantisK, FereidooniD, KhajevandR, et al. . Effect of textural characteristics on engineering properties of some sedimentary rocks [J]. Journal of Central South University, 2021, 28(3): 926-938

[39] ZhangK, ZhangG-M, HouR-B, et al. . Stress evolution in roadway rock bolts during mining in a fully mechanized longwall face, and an evaluation of rock bolt support design [J]. Rock Mechanics and Rock Engineering, 2015, 48(1): 333-344

[40] CaiM-F, HeM-C, LiuD-YRock mechanics and engineering, 2013Second EditionBeijing, Science Press