Macroscopic failure characteristics and seepage pattern of damaged goaf-side coal pillars under confined water accumulation

Authors

LIU Weitao, College of Energy and Mining Engineering, Shandong University of Science and Technology, Qingdao 266590, China; State Key Laboratory of Disaster Prevention and Ecology Protection in Open-pit Coal Mines, Shandong University of Science and Technology, Qingdao 266590, China; College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao 266590, ChinaFollow
CHEN Dongqi, College of Energy and Mining Engineering, Shandong University of Science and Technology, Qingdao 266590, China; State Key Laboratory of Disaster Prevention and Ecology Protection in Open-pit Coal Mines, Shandong University of Science and Technology, Qingdao 266590, ChinaFollow
LIU Yuben, College of Energy and Mining Engineering, Shandong University of Science and Technology, Qingdao 266590, China; State Key Laboratory of Disaster Prevention and Ecology Protection in Open-pit Coal Mines, Shandong University of Science and Technology, Qingdao 266590, China
DU Yanhui, State Key Laboratory of Disaster Prevention and Ecology Protection in Open-pit Coal Mines, Shandong University of Science and Technology, Qingdao 266590, China; College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao 266590, China
ZHAO Jiyuan, State Key Laboratory of Disaster Prevention and Ecology Protection in Open-pit Coal Mines, Shandong University of Science and Technology, Qingdao 266590, China; College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao 266590, China

Abstract

Background The method of supporting roadways using small coal pillars has been widely applied in China. As a result, the stability of goaf-side coal pillars affects mining safety. Resulting from multiple disturbance effects, coal pillars tend to contain various types of damage fractures. The confined water environment in goaves with water accumulation might cause the instability failure of damaged goaf-side coal pillars. Methods To investigate the impacts of the damage fracture structure on coal stability, this study introduced the concept of relatively stable initial damage fractures. Based on the theory of damage mechanics, this study constructed hydro-mechanical-damage (HMD) coupling models for goaf-side coal pillars. Using the COMSOL finite element analysis software, this study explored the seepage failure process of goaf-side coal pillars under unilateral water pressure. Results and Conclusions The results indicate that the mechanical parameters of initial damage fractures significantly influenced the occurrence time of secondary damage to coals, with critical thresholds existing between them. Damage fractures significantly affected the stability of the goaf-side coal pillars. Specifically, under unilateral water pressure, the goaf-side coal pillars exhibited asymmetric failure morphologies, and the seepage velocities at local water-inrush points increased by two orders of magnitude compared to pre-damage states. The fracture structure affected the instability process of coals. As the fracture angle increased from 30° to 60°, the occurrence time of coal instability decreased from 7.0 h to 4.1 h. The model with 0° fractures experienced instability the most quickly (3.9 h) due to the special stress orientation. From the perspective of macroscopic damage development, all models underwent four damage stages: (1) the secondary damage development at tips of initial damage fractures, (2) the damage penetration through boundaries, (3) the large-scale propagation of damage zones, and (4) the formation of pathways for local water inrushes at boundaries. In contrast, the evolutionary characteristics of the quantity of damage units reveal two damage stages: damage development and rapid propagation. The fracture structure affected the damage development rate primarily during the damage development stage, while the duration of the rapid propagation stage differed insignificantly across varying models. The results of this study provide a reference for the stability assessment and instability process identification of water-resisting coals in goaves.

Keywords

goaf-side coal pillar, water accumulation in goaf, initial damage fracture, hydro-mechanical-damage (HMD) coupling model, instability precursor

DOI

10.12363/issn.1001-1986.25.02.0086

Recommended Citation

LIU Weitao, CHEN Dongqi, LIU Yuben, et al. (2025) "Macroscopic failure characteristics and seepage pattern of damaged goaf-side coal pillars under confined water accumulation," Coal Geology & Exploration: Vol. 53: Iss. 8, Article 13.
DOI: 10.12363/issn.1001-1986.25.02.0086
Available at: https://cge.researchcommons.org/journal/vol53/iss8/13

Reference

[1] 武强，刘宏磊，曾一凡，等. 我国绿色矿山建设现状与存在问题及对策建议[J]. 绿色矿山，2023，1(1)：25−32.

WU Qiang，LIU Honglei，ZENG Yifan，et al. Situation，challenges，and proposed strategies for green mine construction in China[J]. Journal of Green Mine，2023，1(1)：25−32.

[2] 孙文洁，李文杰，宁殿艳，等. 我国煤矿水害事故现状、预测及防治建议[J]. 煤田地质与勘探，2023，51(12)：185−194.

SUN Wenjie，LI Wenjie，NING Dianyan，et al. Current states，prediction and prevention suggestions for water hazard accidents in China’s coal mines[J]. Coal Geology & Exploration，2023，51(12)：185−194.

[3] KANG Hongpu，GAO Fuqiang，XU Gang，et al. Mechanical behaviors of coal measures and ground control technologies for China’s deep coal mines：A review[J]. Journal of Rock Mechanics and Geotechnical Engineering，2023，15(1)：37−65.

[4] 周宏伟，谢和平，左建平. 深部高地应力下岩石力学行为研究进展[J]. 力学进展，2005，35(1)：91−99.

ZHOU Hongwei，XIE Heping，ZUO Jianping. Developments in researches on mechanical behaviors of rocks under the condition of high ground pressure in the depths[J]. Advances in Mechanics，2005，35(1)：91−99.

[5] 尹尚先，王玉国，李文生. 矿井水灾害：原因·对策·出路[J]. 煤田地质与勘探，2023，51(1)：214−221.

YIN Shangxian，WANG Yuguo，LI Wensheng. Cause，countermeasures and solutions of water hazards in coal mines in China[J]. Coal Geology & Exploration，2023，51(1)：214−221.

[6] 武强，高俊莲，曾一凡，等. 我国煤矿矿井水全生命周期保护与利用研究[J]. 中国工程科学，2025，27(2)：184−204.

WU Qiang，GAO Junlian，ZENG Yifan，et al. Life–cycle protection and utilization of coal mine water in China[J]. Strategic Study of CAE，2025，27(2)：184−204.

[7] 连野，戚庭野，刘钦. 顶板型老空突水模式及导水通道演化机理研究[J]. 煤矿安全，2023，54(5)：42−48.

LIAN Ye，QI Tingye，LIU Qin. Study on water inrush mode and evolution mechanism of water channel in roof type goaf[J]. Safety in Coal Mines，2023，54(5)：42−48.

[8] 李文，王东昊，李宏杰，等. 煤矿采空区失稳灾害链式效应与链式类型研究[J]. 煤炭科学技术，2020，48(7)：288−295.

LI Wen，WANG Donghao，LI Hongjie，et al. Study on chain effect and type of coal mine goafs instability disaster[J]. Coal Science and Technology，2020，48(7)：288−295.

[9] 郭亚欣，宋选民. 积水采空区下淋水顶板巷道失稳机理研究[J]. 煤炭科学技术，2019，47(11)：36−43.

GUO Yaxin，SONG Xuanmin. Study on instability mechanism of roadway under water–sprinkling roof in water–storage goaf[J]. Coal Science and Technology，2019，47(11)：36−43.

[10] 郑凯歌，张俭，孙四清，等. 煤层顶板多种灾害发生机理与协同防治技术[J]. 煤田地质与勘探，2025，53(5)：24−35.

ZHENG Kaige，ZHANG Jian，SUN Siqing，et al. Mechanisms and collaborative prevention and control techniques for various disasters in coal seam roofs[J]. Coal Geology & Exploration，2025，53(5)：24−35.

[11] 乔伟，李文平，李小琴. 采场顶板离层水“静水压涌突水”机理及防治[J]. 采矿与安全工程学报，2011，28(1)：96−104.

QIAO Wei，LI Wenping，LI Xiaoqin. Mechanism of “hydrostatic water–inrush” and countermeasures for water inrush in roof bed separation of a mining face[J]. Journal of Mining & Safety Engineering，2011，28(1)：96−104.

[12] 马国良，陈曦，范超男，等. 不同水力荷载路径下煤体微观渗流特征及宏观破坏研究[J]. 岩土力学，2023，44(6)：1779−1788.

MA Guoliang，CHEN Xi，FAN Chaonan，et al. Micro seepage characteristics and macro failure of coal under different hydraulic loading paths[J]. Rock and Soil Mechanics，2023，44(6)：1779−1788.

[13] 于永江，刘佳铭，杨云涛，等. 基于能量原理不同含水率下煤岩体变形破坏能量损伤演化机制[J]. 煤炭科学技术，2024，52(6)：67−80.

YU Yongjiang，LIU Jiaming，YANG Yuntao，et al. Mechanical properties and damage constitutive model of coal with different water content based on energy principle[J]. Coal Science and Technology，2024，52(6)：67−80.

[14] 韩鹏华，赵毅鑫，高森，等. 长期水浸作用下煤样渐进破坏特征及损伤本构模型[J]. 岩石力学与工程学报，2024，43(4)：918−933.

HAN Penghua，ZHAO Yixin，GAO Sen，et al. Progressive damage characteristics and damage constitutive model of coal samples under long–term immersion[J]. Chinese Journal of Rock Mechanics and Engineering，2024，43(4)：918−933.

[15] 陈笑予，姚强岭，陈胜焱，等. 基于深部含水煤样失稳特征的荷载梁式主控裂隙模型的试验研究[J]. 岩土力学，2023，44(增刊1)：375−386.

CHEN Xiaoyu，YAO Qiangling，CHEN Shengyan，et al. Experimental study on a loading beam main control crack model based on the instability characteristics of deep coal samples containing water[J]. Rock and Soil Mechanics，2023，44(Sup.1)：375−386.

[16] 刘小玲，张泽天，张茹，等. 浸水煤体单轴压缩能量破坏机理及层理效应[J]. 工程科学与技术，2025，57(1)：189−200.

LIU Xiaoling，ZHANG Zetian，ZHANG Ru，et al. Energy failure mechanism and bedding effect of soaked coal under uniaxial compression[J]. Advanced Engineering Sciences，2025，57(1)：189−200.

[17] FAN Jianyu，LI Zhu，FENG Guorui，et al. Failure analysis of coal pillars and overburden from underground water reservoir under the mining–water invasion coupling effect[J]. Engineering Failure Analysis，2023，151：107406.

[18] 江东海. 单侧低水压作用下临空煤柱变形破坏及锚注加固机理研究[D]. 青岛：山东科技大学，2019.

JIANG Donghai. Deformation and failure and bolting grouting reinforcement mechanism of coal pillar near the goaf under unilateral water with low pressure[D]. Qingdao：Shandong University of Science and Technology，2019.

[19] 余伟健，周明娟. 不同次裂隙数目条件下岩石力学特性及破坏模式[J]. 采矿与安全工程学报，2025，42(2)：394−403.

YU Weijian，ZHOU Mingjuan. Rock mechanics characteristics and failure modes under different number of secondary fractures[J]. Journal of Mining & Safety Engineering，2025，42(2)：394−403.

[20] 谢和平，张泽天，高峰，等. 不同开采方式下煤岩应力场–裂隙场–渗流场行为研究[J]. 煤炭学报，2016，41(10)：2405−2417.

XIE Heping，ZHANG Zetian，GAO Feng，et al. Stress–fracture–seepage field behavior of coal under different mining layouts[J]. Journal of China Coal Society，2016，41(10)：2405−2417.

[21] 尹大伟，丁屹松，汪锋，等. 考虑初始损伤的压力水浸煤岩力学特性试验研究[J]. 煤炭学报，2023，48(12)：4417−4432.

YIN Dawei，DING Yisong，WANG Feng，et al. Experimental study on mechanical properties of coal soaked in pressurized water considering initial damage[J]. Journal of China Coal Society，2023，48(12)：4417−4432.

[22] 康向涛，刘勇，江成玉，等. 含水率对预制裂纹煤样能耗与破坏模式的影响[J]. 中国安全科学学报，2017，27(7)：94−98.

KANG Xiangtao，LIU Yong，JIANG Chengyu，et al. Influence of water content on energy consumption and destruction form of coal samples with prefabricated crack[J]. China Safety Science Journal，2017，27(7)：94−98.

[23] 赵光明，秦志宏，孟祥瑞. 动载循环作用下砂岩的动态力学响应及破坏特征[J]. 采矿与岩层控制工程学报，2025，7(1)：013544.

ZHAO Guangming，QIN Zhihong，MENG Xiangrui. Dynamic mechanical response and failure characteristics of sandstone under dynamic load cycle[J]. Journal of Mining and Strata Control Engineering，2025，7(1)：013544.

[24] JIRÁSEK M，BAUER M. Numerical aspects of the crack band approach[J]. Computers & Structures，2012，110：60−78.

[25] 朱万成，魏晨慧，田军，等. 岩石损伤过程中的热–流–力耦合模型及其应用初探[J]. 岩土力学，2009，30(12)：3851−3857.

ZHU Wancheng，WEI Chenhui，TIAN Jun，et al. Coupled thermal–hydraulic–mechanical model during rock damage and its preliminary application[J]. Rock and Soil Mechanics，2009，30(12)：3851−3857.

[26] LEI Qinghua，DOONECHALY N G，TSANG C F. Modelling fluid injection–induced fracture activation，damage growth，seismicity occurrence and connectivity change in naturally fractured rocks[J]. International Journal of Rock Mechanics and Mining Sciences，2021，138：104598.

[27] RUTQVIST J，TSANG C F. A study of caprock hydromechanical changes associated with CO₂–injection into a brine formation[J]. Environmental Geology，2002，42(2)：296−305.

[28] TANG Chun’an，LIANG Zhengzhao，ZHANG Yongbin，et al. Fracture spacing in layered materials：A new explanation based on two–dimensional failure process modeling[J]. American Journal of Science，2008，308(1)：49−72.

[29] TAO Jian，SHI Anchi，LI Hongtao，et al. Thermal–mechanical modelling of rock response and damage evolution during excavation in prestressed geothermal deposits[J]. International Journal of Rock Mechanics and Mining Sciences，2021，147：104913.

[30] ADLER P M，THOVERT J F. Fractures and fracture networks[M]. Dordrecht：Springer，1999.

[31] 姬红英，王文博，辛亚军，等. 水力耦合下煤样声发射分形–渗透率模型及试验研究[J]. 煤炭学报，2024，49(8)：3381−3398.

JI Hongying，WANG Wenbo，XIN Yajun，et al. Acoustic emission fractal–permeability model and experimental study of coal specimens under hydraulic–loading coupling[J]. Journal of China Coal Society，2024，49(8)：3381−3398.

[32] 林海飞，李博涛，李树刚，等. 液氮致裂层理煤体热–流–固–损伤耦合模型及数值模拟研究[J]. 岩石力学与工程学报，2024，43(5)：1110−1123.

LIN Haifei，LI Botao，LI Shugang，et al. A thermal–hydraulic–mechanical–damage coupling model of layer coal fracturing by liquid nitrogen[J]. Chinese Journal of Rock Mechanics and Engineering，2024，43(5)：1110−1123.

[33] 唐春安. 岩石声发射规律数值模拟初探[J]. 岩石力学与工程学报，1997，16(4)：368−374.

TANG Chun’an. Numerical simulation of ae in rock failure[J]. Chinese Journal of Rock Mechanics and Engineering，1997，16(4)：368−374.