Fructure mechanisms and fracture distribution patterns of main roofs in goaves within abandoned mines

Authors

TAO Xuefeng, School of Safety Science and Engineering, Anhui University of Science and Technology, Huainan 232001, ChinaFollow
SHI Biming, School of Safety Science and Engineering, Anhui University of Science and Technology, Huainan 232001, ChinaFollow
HUA Xinzhu, School of Safety Science and Engineering, Anhui University of Science and Technology, Huainan 232001, China
LIN Baiquan, School of Safety Engineering, China University of Mining and Technology, Xuzhou 221116, China
YUE Jiwei, School of Safety Science and Engineering, Anhui University of Science and Technology, Huainan 232001, China
LIANG Yuehui, School of Safety Science and Engineering, Anhui University of Science and Technology, Huainan 232001, China
ZHANG Chengcheng, School of Safety Science and Engineering, Anhui University of Science and Technology, Huainan 232001, China
QIN Hao, School of Safety Science and Engineering, Anhui University of Science and Technology, Huainan 232001, China
YANG Yong, School of Safety Science and Engineering, Anhui University of Science and Technology, Huainan 232001, China
XUE Yonglin, School of Safety Science and Engineering, Anhui University of Science and Technology, Huainan 232001, China

Abstract

Objective In abandoned mines, the storage zones of free gas are closely associated with overburden fractures in goaves. To accurately estimate free gas resources in abandoned mines, it is necessary to thoroughly investigate the rupture mechanisms of blocks in main roofs in goaves, as well as the overburden fractures and rupture trace morphologies in goaves. Methods Based on the masonry beam theory, this study established a mechanical model for the primary cantilever beam of a main roof. The analytical solutions of the stress components in the primary cantilever beam were analyzed using the stress inverse method, and the mathematical expression of periodic rupture traces was derived based on the Mohr-Coulomb failure criterion. Using the general rock mechanical parameters of the main roofs of goaves of various coal seams in the Panyi Mine in the Huainan mining area, Anhui Province, this study analyzed the stresses and strains of the primary cantilever beam, along with the strain energy density of the beam under different elastic moduli and Poisson's ratios. The rupture traces were calculated and plotted using the Maple software, and the influences of the internal friction angle and cohesive force on the rupture traces were analyzed. By constructing the experimental platform for physical simulation of mining face 1252-1 in the Panyi Mine using similar materials, this study analyzed the fracture network in the overburden in the goaf using the ImageJ software. Results and Conclusions The results indicate that the rupture of the primary cantilever beam of a main roof was primarily affected by horizontal and shear stresses, with tensile-shear failure predominating. The primary cantilever beam fracturing occurred initially in the compressed zone on its upper surface and then propagated toward the compressed zone on its lower surface. Substituting the overburden parameters of goaves in the Panyi Mine into the rupture trace expression yielded two parallel L-shaped rupture traces (i.e., rupture traces I and II). The rupture traces extended vertically from the top of the simulated block downward until inflection points and then propagated back downward to the bottom of the block. With an increase in the cohesive force, the number of rupture traces increased from two to three. Fracture traces I and II exhibited an L-shaped pattern, extending to the right side, whereas rupture trace III gradually extended vertically to the bottom of the block. The scanning results of overburden fractures in the goaf obtained using ImageJ software revealed that zones I-1 and I-2 were median-elevation gas enrichment areas, while zones II-1 and II-2 were high-elevation gas enrichment areas. The results of this study provide a scientific basis for designing the locations of gas drainage boreholes in an abandoned mine while also offering a reference for similar mines.

Keywords

main roof, primary cantilever beam, strain energy, rupture trace, fracture network, abandoned mine

DOI

10.12363/issn.1001-1986.25.05.0347

Recommended Citation

TAO Xuefeng, SHI Biming, HUA Xinzhu, et al. (2025) "Fructure mechanisms and fracture distribution patterns of main roofs in goaves within abandoned mines," Coal Geology & Exploration: Vol. 53: Iss. 11, Article 11.
DOI: 10.12363/issn.1001-1986.25.05.0347
Available at: https://cge.researchcommons.org/journal/vol53/iss11/11

Reference

[1] WANG Shaofeng，LI Xibing. Dynamic distribution of longwall mining–induced voids in overlying strata of a coalbed[J]. International Journal of Geomechanics，2017，17(6)：04016124.

[2] LI Yingchun. Analytical examination for the stability of a competent stratum and implications for longwall coal mining[J]. Energy Science & Engineering，2019，7(2)：469−477.

[3] YU Bin，GAO Rui，KUANG Tiejun，et al. Engineering study on fracturing high–level hard rock strata by ground hydraulic action[J]. Tunnelling and Underground Space Technology，2019，86：156−164.

[4] FENG Guorui，ZHANG Ao，HU Shengyong，et al. A methodology for determining the methane flow space in abandoned mine gobs and its application in methane drainage[J]. Fuel，2018，227：208−217.

[5] LI Yankui，WU Shiyue，NIE Baisheng，et al. A new pattern of underground space–time tridimensional gas drainage：A case study in Yuwu Coal Mine，China[J]. Energy Science & Engineering，2019，7(2)：399−410.

[6] YUE Gaowei，LIU Hui，YUE Jiwei，et al. Influence radius of gas extraction borehole in an anisotropic coal seam：Underground in–situ measurement and modeling[J]. Energy Science & Engineering，2019，7(3)：694−709.

[7] 左建平，于美鲁，孙运江，等. 不同厚度岩层破断模式转变机理及力学模型分析[J]. 煤炭学报，2023，48(4)：1449−1463.

ZUO Jianping，YU Meilu，SUN Yunjiang，et al. Analysis of fracture mode transformation mechanism and mechanical model of rock strata with different thicknesses[J]. Journal of China Coal Society，2023，48(4)：1449−1463.

[8] 张纯旺. 废弃矿井采空区覆岩裂隙导通机理及多尺度渗流特性研究[D]. 太原：太原理工大学，2021.

ZHANG Chunwang. Formation mechanism and multi–scale seepage characteristics of overburden fracture in abandoned coal mine[D]. Taiyuan：Taiyuan University of Technology，2021.

[9] 张广超，尹茂胜，周广磊，等. 厚硬岩层下板结构破断应力–能量场积聚演化规律[J]. 中国矿业大学学报，2024，53(4)：647−663.

ZHANG Guangchao，YIN Maosheng，ZHOU Guanglei，et al. Evolution law of stress and energy field accumulation during the fracture of plate structure in thick and hard rock strata[J]. Journal of China University of Mining & Technology，2024，53(4)：647−663.

[10] 潘岳，顾士坦. 基于软化地基和弹性地基假定的坚硬顶板力学特性分析[J]. 岩石力学与工程学报，2015，34(7)：1402−1414.

PAN Yue，GU Shitan. Mechanical properties of hard roof based on assumptions of soften foundation and elastic foundation[J]. Chinese Journal of Rock Mechanics and Engineering，2015，34(7)：1402−1414.

[11] 赵雁海，宋选民. 浅埋超长工作面裂隙梁铰拱结构稳定性分析及数值模拟研究[J]. 岩土力学，2016，37(1)：203−209.

ZHAO Yanhai，SONG Xuanmin. Stability analysis and numerical simulation of hinged arch structure for fractured beam in super–long mining workface under shallow seam[J]. Rock and Soil Mechanics，2016，37(1)：203−209.

[12] 杨胜利，王家臣，李良晖. 基于中厚板理论的关键岩层变形及破断特征研究[J]. 煤炭学报，2020，45(8)：2718−2727.

YANG Shengli，WANG Jiachen，LI Lianghui. Deformation and fracture characteristics of key strata based on the medium thick plate theory[J]. Journal of China Coal Society，2020，45(8)：2718−2727.

[13] 张亮亮，程桦. 基于逆解法–半逆解法的煤层仰采基本顶周期来压步距计算模型研究[J/OL]. 工程力学，2024：1–10 [2024-09-18]. https://kns.cnki.net/kcms/detail/detail.aspx?dbcode=CJFD&dbname=CJFD&filename=GCLX2024091400Y.

ZHANG Liangliang，CHENG Hua. Research on the calculation model of the basic roof periodic weighting step for topple mining based on inverse solution and semi inverse solution[J/OL]. Engineering Mechanics，2024：1–10 [2024-09-18]. https://kns.cnki.net/kcms/detail/detail.aspx?dbcode=CJFD&dbname=CJFD&filename=GCLX2024091400Y.

[14] 梁冰，邢景超，孙维吉，等. 采动覆岩破断影响下裂隙诱发机制及三维空间特征[J]. 煤炭科学技术，2025，53(1)：107−121.

LIANG Bing，XING Jingchao，SUN Weiji，et al. Mechanisms and three–dimensional spatial characteristics of fissures induced under the influence of fracture of mining overburden rocks[J]. Coal Science and Technology，2025，53(1)：107−121.

[15] 韩红凯，史灿，许家林，等. 基于采动覆岩关键层“板–梁”结构的应力场预测模型研究[J]. 采矿与安全工程学报，2024，41(6)：1190−1201.

HAN Hongkai，SHI Can，XU Jialin，et al. Mining–induced stress field prediction model based on the “slab–beam” structure of overburden key strata[J]. Journal of Mining & Safety Engineering，2024，41(6)：1190−1201.

[16] 余伊河，马立强，张东升，等. 长壁工作面采动覆岩层理开裂机理及侧向裂隙发育规律[J]. 煤炭学报，2023，48(增刊2)：527−541.

YU Yihe，MA Liqiang，ZHANG Dongsheng，et al. Mechanism of bedding cracking and development laws of lateral fracture in overlying strata induced by longwall mining[J]. Journal of China Coal Society，2023，48(Sup.2)：527−541.

[17] 吕凯，何富连，许旭辉，等. 异形载荷–弹性基础基本顶板结构破断特征及稳定性分析[J]. 岩石力学与工程学报，2023，42(4)：930−947.

LYU Kai，HE Fulian，XU Xuhui，et al. Fracture characteristics and stability analysis of main roof plate structure with special–shaped load and elastic foundation[J]. Chinese Journal of Rock Mechanics and Engineering，2023，42(4)：930−947.

[18] 徐超，王凯，郭琳，等. 采动覆岩裂隙与渗流分形演化规律及工程应用[J]. 岩石力学与工程学报，2022，41(12)：2389−2403.

XU Chao，WANG Kai，GUO Lin，et al. Fractal evolution law of overlying rock fracture and seepage caused by mining and its engineering application[J]. Chinese Journal of Rock Mechanics and Engineering，2022，41(12)：2389−2403.

[19] 乔伟，程香港，窦林名，等. 深部矿井覆岩沉积环境–力学特性及冲击地压风险判识[J]. 煤田地质与勘探，2024，52(10)：60−71.

QIAO Wei，CHENG Xianggang，DOU Linming，et al. Sedimentary environments，mechanical properties，and rock burst risk identification of overburden in deep mines[J]. Coal Geology & Exploration，2024，52(10)：60−71.

[20] 汪北方，吕元昊，张晶. 浅埋复合采空区覆岩采动裂隙分区特征及其治理技术[J]. 煤炭科学技术，2025，53(2)：41−52.

WANG Beifang，LYU Yuanhao，ZHANG Jing. Zone feature and control technology of overlying strata mining–induced fracture in shallow buried compound goaf[J]. Coal Science and Technology，2025，53(2)：41−52.

[21] WANG Feng，XU Jialin，XIE Jianlin. Effects of arch structure in unconsolidated layers on fracture and failure of overlying strata[J]. International Journal of Rock Mechanics and Mining Sciences，2019，114：141−152.

[22] LI Bo，LIANG Yunpei，ZOU Quanle. Determination of working resistance based on movement type of the first subordinate key stratum in a fully mechanized face with large mining height[J]. Energy Science & Engineering，2019，7(3)：777−798.

[23] 郭恒. 复杂条件下陕北浅埋煤层采空区的综合探查技术研究[J]. 地质与勘探,2025,61(2):385−394

GUO Heng. Comprehensive exploration technology on shallow buried coal seam goaf in northern shaanxi under complex conditions[J]. Geology and Exploration,2025,61(2):385−394

[24] TAN Yunliang，LIU Xuesheng，NING Jianguo，et al. In situ investigations on failure evolution of overlying strata induced by mining multiple coal seams[J]. Geotechnical Testing Journal，2017，40(2)：244−257.

[25] LAN Yiwen，GAO Rui，YU Bin，et al. In situ studies on the characteristics of strata structures and behaviors in mining of a thick coal seam with hard roofs[J]. Energies，2018，11(9)：2470.

[26] WANG Gang，WU Mengmeng，WANG Rui，et al. Height of the mining–induced fractured zone above a coal face[J]. Engineering Geology，2017，216：140−152.

[27] 孟凡非，浦海，倪宏阳，等. 关闭矿井采空区破碎岩体再断裂机制及空隙结构演化特性[J]. 煤炭科学技术，2024，52(2)：104−114.

MENG Fanfei，PU Hai，NI Hongyang，et al. Research on re–fracturing mechanism and cavity structure evolution characteristics of broken rock mass in goaf of closed mine[J]. Coal Science and Technology，2024，52(2)：104−114.

[28] 王波. 鸡西矿区封闭采空区煤层气开发甜点区优选及负压抽采工艺[D]. 徐州：中国矿业大学，2021.

WANG Bo. Sweet spots selection for coalbed methane development and negative pressure extraction technology from closed gob in Jixi mining area[D]. Xuzhou：China University of Mining and Technology，2021.

[29] 张小龙，王飞，刘红威，等. 基于采动覆岩三维裂隙场演化规律的地面L型钻井瓦斯抽采技术[J]. 中国安全生产科学技术，2022，18(10)：56−61.

ZHANG Xiaolong，WANG Fei，LIU Hongwei，et al. Study on gas drainage technology of ground L–type drilling based on evolution law of three–dimensional fracture field in mining overburden rock[J]. Journal of Safety Science and Technology，2022，18(10)：56−61.

[30] 钱鸣高，石平五，许家林. 矿山压力与岩层控制(第2版)[M]. 徐州：中国矿业大学出版社，2010.

[31] 孙建，王连国，鲁海峰. 基于隔水关键层理论的倾斜煤层底板突水危险区域分析[J]. 采矿与安全工程学报，2017，34(4)：655−662.

SUN Jian，WANG Lianguo，LU Haifeng. The analysis of the water–inrush dangerous areas in the inclined coal seam floor based on the theory of water–resisting key strata[J]. Journal of Mining & Safety Engineering，2017，34(4)：655−662.

[32] 谢立栋，东兆星，张涛，等. 立井爆破掘进空隙高度优化设计的小波包分析[J]. 煤矿安全，2018，49(12)：229−234.

XIE Lidong，DONG Zhaoxing，ZHANG Tao，et al. Wavelet packet analysis for optimization design of gap height in shaft blasting excavation[J]. Safety in Coal Mines，2018，49(12)：229−234.

[33] 金俊超，景来红，杨风威，等. 基于Mohr–Coulomb准则的岩石弹塑性损伤模型应力更新算法研究[J]. 工程力学，2025，42(5)：9−20.

JIN Junchao，JING Laihong，YANG Fengwei，et al. A numerical algorithm of elastoplastic damage constitutive model of rock based on Mohr–Coulomb criterion[J]. Engineering Mechanics，2025，42(5)：9−20.

[34] 孔祥国，赵天烁，林海飞，等. 特厚煤层覆岩裂隙–渗流区域演化规律及工程应用[J]. 煤田地质与勘探，2025，53(1)：102−113.

KONG Xiangguo，ZHAO Tianshuo，LIN Haifei，et al. Fracture–seepage characteristic zones of the overburden of extra–thick coal seams：Evolutionary patterns and their engineering applications[J]. Coal Geology & Exploration，2025，53(1)：102−113.