Mechanisms behind the control of floor failure in deep coal mines by hydraulic fracturing based on power-law fracture networks

Authors

DUAN Hongfei, School of Civil Engineering, Sun Yat-sen University, Zhuhai 519082, China; State Key Laboratory for Tunnel Engineering, Sun Yat-sen University, Guangzhou 510275, ChinaFollow
YE Dayu, School of Civil Engineering, Sun Yat-sen University, Zhuhai 519082, China; State Key Laboratory for Tunnel Engineering, Sun Yat-sen University, Guangzhou 510275, ChinaFollow
ZHAO Lijuan, School of Civil Engineering, Sun Yat-sen University, Zhuhai 519082, China; State Key Laboratory for Tunnel Engineering, Sun Yat-sen University, Guangzhou 510275, ChinaFollow
ZENG Yifan, Inner Mongolia Research Institute, China University of Mining and Technology (Beijing), Ordos 017010, China; National Coal Mine Water Hazard Prevention Engineering Technology Research Center, China University of Mining and Technology (Beijing), Beijing 100083, China
ZOU Junpeng, Faculty of Engineering, China University of Geosciences, Wuhan 430074, China
YU Guofeng, School of Civil Engineering, Sun Yat-sen University, Zhuhai 519082, China; State Key Laboratory for Tunnel Engineering, Sun Yat-sen University, Guangzhou 510275, China; State Key Laboratory for Safe Mining of Deep Coal Resources and Environment Protection, Huainan Mining Group Co., Ltd., Huainan 232001, China
MENG Xiang, School of Civil Engineering, Sun Yat-sen University, Zhuhai 519082, China; State Key Laboratory for Tunnel Engineering, Sun Yat-sen University, Guangzhou 510275, ChinaFollow

Abstract

Objective Hydraulic fracturing of coal seam floors represents an important technical approach to mitigating damage to the floor rock masses through proactive pressure relief and to improving seepage pathways. However, there is a lack of systematic, quantitative insights into the evolutionary characteristics of floor fracture networks, as well as their impacts on the stress redistribution and rock stability of coal seam floors, during hydraulic fracturing.Methods This study aims to address the challenge that is prone to cause severe damage to the floor rock masses. First, a coal seam floor was considered a saturated porous medium containing multi-scale fractures based on power-law fracture networks and the fluid-solid coupling theory. Then, by incorporating three statistical parameters, i.e., the power-law exponent of fractures, maximum fracture length, and fracture length ratio, this study established a fluid-solid-fracture coupling model for the hydraulic fracturing of coal seam floors for the unified characterization of primary and hydraulic-fracturing-induced fractures. This model facilitates the quantitative and comprehensive analysis of the evolution characteristics of floor fracture networks. Subsequently, the model’s capabilities to characterize fluid migration and stress redistribution under the control of fracture networks were verified using data from laboratory seepage experiments and on-site engineering of fracture media. Finally, this model was applied to the coal seam floor of mining face 1221(3)W in a coal mine within the Huainan mining area, Anhui Province to analyze the spatiotemporal evolution characteristics of stress along the central line of the floor under the presence of confined aquifers or injection boundary conditions. These characteristics, combined with time-varying curves of the axial stress and acoustic emission R-value at the monitoring points for floor failure, provided a reference for the stress evolution and failure criteria in the numerical model. Results and Conclusions The calculation results of mining face 1221(3)W derived using the proposed coupling model indicate that the statistical characteristics of fractures exerted significantly different impacts on the floor stress. Specifically, the maximum stress applied to the rock masses of the coal seam floor increased by approximately 24.91% as the power-law exponent of fractures decreased to 1.3 from 1.7, increased by approximately 43.71% when the maximum fracture length increased from 0.012 m to 0.020 m, and increased by approximately 10.85% as the fracture length ratio increased from 0.002 to 0.010. Therefore, the maximum fracture length was identified as the most sensitive parameter for controlling the stress concentration and stability of the coal seam floor, followed by the power-law exponent of fractures, with the fracture length ratio producing relatively weak impacts. Additionally, the results reveal that a small number of long, highly penetrating fractures in coal seam floors play a predominant role in stress concentration and the expansion of hydraulically conductive fracture zones. Therefore, the identification and control of these fractures should be highlighted in the hydraulic fracturing design of coal seam floors. Overall, the results of this study provide a reference for the stability assessment of coal seam floors and the prevention and control of their water inrush risk in deep coal mines.

Keywords

deep coal mining, hydraulic fracturing of coal seam floors, power-law fracture network, fluid-solid coupling, coal seam floor stress, water inrush risk

DOI

10.12363/issn.1001-1986.25.12.0925

Recommended Citation

DUAN Hongfei, YE Dayu, ZHAO Lijuan, et al. (2026) "Mechanisms behind the control of floor failure in deep coal mines by hydraulic fracturing based on power-law fracture networks," Coal Geology & Exploration: Vol. 54: Iss. 3, Article 13.
DOI: 10.12363/issn.1001-1986.25.12.0925
Available at: https://cge.researchcommons.org/journal/vol54/iss3/13

Reference

[1] 周宏伟，张茹，薛东杰，等. 深部煤炭资源流态化开采原位多场多相岩体力学理论研究前沿[J/OL]. 煤炭学报，2025：1–20(2026-01-15)[2025-12-15]. https://link.cnki.net/urlid/11.2190.TD.20251215.1505.002.

ZHOU Hongwei，ZHANG Ru，XUE Dongjie，et al. Theoretical frontiers of in–situ rock mechanics under multi–physics–phase coupling in deep exploration of fluidized coal mining[J/OL]. Journal of China Coal Society，2025：1–20(2026-01-15)[2025-12-15]. https://link.cnki.net/urlid/11.2190.TD.20251215.1505.002.

[2] 许光泉，张海涛，梁淼，等. 我国典型煤矿区矿井水水质特征、影响因素及污染防控研究进展[J/OL]. 煤田地质与勘探，2025：1–14 (2026-01-15)[2025-12-26]. https://link.cnki.net/urlid/61.1155.p.20251225.1656.002.

XU Guangquan，ZHANG Haitao，LIANG Miao，et al. Research progress on water quality characteristics，influencing factors，and pollution prevention and control of mine water in typical coal mining areas in China[J/OL]. Coal Geology & Exploration，2025：1–14 (2026-01-15)[2025-12-26]. https://link.cnki.net/urlid/61.1155.p.20251225.1656.002.

[3] 杨庆贺. 带压开采煤层底板突水危险性评价及治理研究[D]. 阜新：辽宁工程技术大学，2024.

YANG Qinghe. Risk assessment and treatment research on water inrush from coal seam floor during mining[D]. Fuxin：Liaoning Technical University，2024.

[4] 段宏飞,姜振泉,张蕊,等. 杨村煤矿综采条件下薄煤层底板破坏深度的实测与模拟研究[J]. 煤炭学报,2011,36(增刊1):13−17

DUAN Hongfei,JIANG Zhenquan,ZHANG Rui,et al. Field measurement and simulation research on failure depth of fully mechanized thin coal seam floor in Yangcun Coal Mine[J]. Journal of China Coal Society,2011,36(Sup.1):13−17

[5] 鲁俊，熊紫阳，谢和平，等. 真三轴应力下复合煤岩力学行为与能量演化特性研究[J/OL]. 采矿与岩层控制工程学报，2025：1–18 (2026-01-15)[2025-10-30]. https://link.cnki.net/urlid/10.1638.td.20251030.1334.006.

LU Jun，XIONG Ziyang，XIE Heping，et al. Research on the load–bearing mechanical behavior and energy evolution characteristics of composite coal–rock under true triaxial conditions[J/OL]. Journal of Mining and Strata Control Engineering，2025：1–18(2026-01-15)[2025-10-30]. https://link.cnki.net/urlid/10.1638.td.20251030.1334.006.

[6] 段宏飞. 煤矿底板采动变形及带压开采突水评判方法研究[D]. 徐州：中国矿业大学，2012.

DUAN Hongfei. Study on mining deformation of floor and evaluation method of water inrush mining above confined aquifer[D]. Xuzhou：China University of Mining and Technology，2012.

[7] 董书宁,王皓,张文忠. 华北型煤田奥灰顶部利用与改造判别准则及底板破坏深度[J]. 煤炭学报,2019,44(7):2216−2226

DONG Shuning,WANG Hao,ZHANG Wenzhong. Judgement criteria with utilization and grouting reconstruction of top Ordovician limestone and floor damage depth in North China coal field[J]. Journal of China Coal Society,2019,44(7):2216−2226

[8] 张平松,欧元超. 煤层采动底板突水物理模拟试验研究进展与展望[J]. 煤田地质与勘探,2024,52(6):44−56

ZHANG Pingsong,OU Yuanchao. Physical simulation experiments on mining-induced water inrushes from coal seam floors:Advances in research and prospects[J]. Coal Geology & Exploration,2024,52(6):44−56

[9] 段宏飞. 底板破坏深度六因素线性预测模型[J]. 岩土力学,2014,35(11):3323−3330

DUAN Hongfei. Six factors linear prediction model on depth of damage floor[J]. Rock and Soil Mechanics,2014,35(11):3323−3330

[10] 王俊光,杨松,马峥,等. 动力扰动下底板突水前兆特征及危险性评价[J]. 力学学报,2025,57(7):1671−1687

WANG Junguang,YANG Song,MA Zheng,et al. Precursor characteristics of floor water inrush and risk assessment under dynamic disturbance[J]. Chinese Journal of Theoretical and Applied Mechanics,2025,57(7):1671−1687

[11] 胡卫玉,尹尚先. 煤层底板突水的动力机制及应用[J]. 岩石力学与工程学报,2010,29(增刊1):2713−2718

HU Weiyu,YIN Shangxian. Dynamic mechanism and application of coal seam floor water inrush[J]. Chinese Journal of Rock Mechanics and Engineering,2010,29(Sup.1):2713−2718

[12] 左建平,吴根水. 深部底板水锤突水效应及递进–导升力学模型研究[J]. 岩石力学与工程学报,2024,43(8):1852−1869

ZUO Jianping,WU Genshui. Research on water inrush caused by water hammer effect and progressive-lift mechanical model of deep floor[J]. Chinese Journal of Rock Mechanics and Engineering,2024,43(8):1852−1869

[13] 孙文斌,张士川,李杨杨,等. 固流耦合相似模拟材料研制及深部突水模拟试验[J]. 岩石力学与工程学报,2015,34(增刊1):2665−2670

SUN Wenbin,ZHANG Shichuan,LI Yangyang,et al. Development application of solid–fluid coupling similar material for floor strata and simulation test of water–inrush in deep mining[J]. Chinese Journal of Rock Mechanics and Engineering,2015,34(Sup.1):2665−2670

[14] LI Wai,LIU Jishan,ZENG Jie,et al. A fully coupled multidomain and multiphysics model for evaluation of shale gas extraction[J]. Fuel,2020,278:118214.

[15] ZHANG Shuo,SONG Shengyuan,ZHANG Wen,et al. Research on the inherent mechanism of rock mass deformation of oil shale in– situ mining under the condition of thermal–fluid–solid coupling[J]. Energy,2023,280:128149.

[16] 刘冠男,叶大羽,高峰,等. 幂率型裂隙分布煤层渗流场与变形应力场耦合模型及数值模拟[J]. 岩石力学与工程学报,2022,41(3):492−502

LIU Guannan,YE Dayu,GAO Feng,et al. Coupled model of seepage and deformation fields in power–law fracture–distributed coal seam[J]. Chinese Journal of Rock Mechanics and Engineering,2022,41(3):492−502

[17] ZHAO Lijuan,GAO Mingzhong,LEI Nengzhong,et al. 3D forward modeling and response characteristics of low–resistivity overburden of the CFS–PML absorbing boundary for ground–well transient electromagnetic method[J]. International Journal of Mining Science and Technology,2023,33(12):1541−1550.

[18] 盖秋凯,高玉兵,何满潮. 承压水上无煤柱自成巷开采底板破坏特征模型试验研究[J]. 岩石力学与工程学报,2025,44(2):391−408

GAI Qiukai,GAO Yubing,HE Manchao. Model experimental study of floor failure characteristics during non-pillar mining with automatically formed roadway above confined water[J]. Chinese Journal of Rock Mechanics and Engineering,2025,44(2):391−408

[19] DONG Donglin,ZHANG Jialun. Discrimination methods of mine inrush water source[J]. Water,2023,15(18):3237.

[20] WU Jiansong,XU Shengdi,ZHOU Rui,et al. Scenario analysis of mine water inrush hazard using Bayesian networks[J]. Safety Science,2016,89:231−239.

[21] 卢兴州,杨登峰,王波,等. 静动载作用下巷道底板突水过程及关键致灾因素模拟[J]. 科学技术与工程,2024,24(29):12506−12515

LU Xingzhou,YANG Dengfeng,WANG Bo,et al. Simulation of water inrush from roadway floor and key disaster-causing factors under static and dynamic loads[J]. Science Technology and Engineering,2024,24(29):12506−12515

[22] GUO Baohua,CHENG Tan,WANG Long,et al. Physical simulation of water inrush through the mine floor from a confined aquifer[J]. Mine Water and the Environment,2018,37(3):577−585.

[23] ZHANG Shichuan,SHEN Baotang,LI Yangyang,et al. Modeling rock fracture propagation and water inrush mechanisms in underground coal mine[J]. Geofluids,2019,2019:1796965.

[24] ODINTSEV V N,MILETENKO N A. Water inrush in mines as a consequence of spontaneous hydrofracture[J]. Journal of Mining Science,2015,51(3):423−434.

[25] YE Dayu,SUN Meng,LIN Xiang,et al. Fractal modelling of freeze–thaw in cold–region concrete:Quantitative micro–network evolution and hydro–thermo–mechanical assessment[J]. International Journal of Heat and Mass Transfer,2024,225:125450.

[26] LIU Guannan,LIU Jishan,LIU Liu,et al. A fractal approach to fully–couple coal deformation and gas flow[J]. Fuel,2019,240:219−236.

[27] YU Boming,CHENG Ping. A fractal permeability model for bi–dispersed porous media[J]. International Journal of Heat and Mass Transfer,2002,45(14):2983−2993.

[28] 赵晨德,王心义,任君豪,等. 基于深度学习理论的煤层底板突水危险性预测[J]. 地下空间与工程学报,2023,19(6):2090−2100

ZHAO Chende,WANG Xinyi,REN Junhao,et al. Prediction of water inrush risk from coal seam floor based on deep learning theory[J]. Chinese Journal of Underground Space and Engineering,2023,19(6):2090−2100

[29] 李点尚,张海骄,孙乐乐,等. 深埋矿井切顶卸压保护底板采区大巷技术研究[J]. 煤炭科技,2024,45(2):134−141

LI Dianshang,ZHANG Haijiao,SUN Lele,et al. Research on technology of roof cutting and pressure relief to protect roadway in floor mining area of deep buried mines[J]. Coal Science & Technology Magazine,2024,45(2):134−141

[30] HARPALANI S,SCHRAUFNAGEL A. Measurement of parameters impacting methane recovery from coal seams[J]. International Journal of Mining and Geological Engineering,1990,8(4):369−384.

[31] SHI Xuyang,ZHOU Wei,CAI Qingxiang,et al. Experimental study on nonlinear seepage characteristics and particle size gradation effect of fractured sandstones[J]. Advances in Civil Engineering,2018,2018:8640535.