An experimental study of the evolutionary patterns of mechanical properties of coals under multiple mining disturbances

Authors

OUYANG Zhenhua, School of Mine Safety, North China Institute of Science and Technology, Langfang 065201, China; School of Mechanics & Engineering, Liaoning Technical University, Fuxin 123000, ChinaFollow
LIU Yang, School of Mechanics & Engineering, Liaoning Technical University, Fuxin 123000, ChinaFollow
LI Chunlei, China Institute of Water Resources and Hydropower Research, Beijing 100048, China
SHI Qingwen, School of Mine Safety, North China Institute of Science and Technology, Langfang 065201, China
LI Wenshuai, School of Mine Safety, North China Institute of Science and Technology, Langfang 065201, China
YI Haiyang, School of Mine Safety, North China Institute of Science and Technology, Langfang 065201, China
QIN Hongyan, School of Mine Safety, North China Institute of Science and Technology, Langfang 065201, China
ZHANG Ningbo, School of Mine Safety, North China Institute of Science and Technology, Langfang 065201, China

Abstract

Objective In the mining process of coal mines, the cyclic loading and unloading effects caused by multiple mining disturbances can alter the mechanical properties of coals, serving as a significant cause of rock bursts. Revealing the response characteristics of crucial mechanical parameters and the damage mechanisms of coals can provide a basis for discriminating the impact-induced instability state, holding great significance for enhancing disaster prediction capabilities. Methods Quasi-static uniaxial cyclic loading and unloading experiments and the dynamic impact loading experiments on large-size coal-like specimens were combined to accurately capture the stress, strain, and acoustic emission responses during the experiments, thoroughly unveiling the laws of changes in mechanical parameters and the damage evolutionary processes of the specimens under the action of multiple mining disturbances. Results and Conclusions Key findings are as follows: (1) The maximum load is identified as the most critical factor influencing the mechanical properties of the coals damaged by multiple cyclic loading and unloading processes. With an increase in the number of cycles, the specimen in the yield stage under loading displayed increasing, decreasing, and then increasing residual strain. Meanwhile, it exhibited gradually increasing dissipated energy density and acoustic emission characteristic value corresponding to the maximum load, suggesting escalating damage degrees of the specimens. For the specimen in the elastic stage under loading, all the mechanical parameters mentioned above first decreased and then increased. In contrast, for the specimen remaining in the compaction stage throughout the experiment, the three sets of data manifested gradually decreasing trends. (2) Under dynamic impact loading, all of the three specimens experienced impact-induced failure. The specimen subjected to a lower load in the earlier quasi-static cyclic loading and unloading experiments exhibited less damage, higher dynamic load strength required for impact-induced failure, and higher elastic moduli corresponding to the failure at peak strength. (3) The damage degrees of the specimens were characterized from both strain and energy perspectives. A comparative analysis revealed that energy damage degrees proved more sensitive in discriminating the damage degrees of the specimens in the experiment process. (4) Observations of the impact fracture characteristics inside the specimens suggest that the specimens experienced the quiet, particle ejection, stability failure, and impact-induced failure stages in the process of impact-induced failure. (5) The value of residual strain, when it began to increase, in the late stage of cyclic loading and unloading, as well as the early stage of stability failure in the impact-induced failure process can be used as early-warning information for the impact-induced instability of damaged coals. This study, having obtained the evolutionary patterns of the mechanical properties of coals subjected to multiple mining disturbances, can provide a theoretical basis for determining the impact-induced instability state of damaged coals in engineering construction. Furthermore, it holds great significance for promptly identifying the potential instability risks of damaged coals and thereby optimizing the supporting schemes and ensuring the safe mining of mines.

Keywords

mine safety, mining disturbance, dynamic impact loading, acoustic emission, mechanical property, damage mechanism, damage degree, early-warning information

DOI

10.12363/issn.1001-1986.24.04.0274

Recommended Citation

OUYANG Zhenhua, LIU Yang, LI Chunlei, et al. (2024) "An experimental study of the evolutionary patterns of mechanical properties of coals under multiple mining disturbances," Coal Geology & Exploration: Vol. 52: Iss. 10, Article 8.
DOI: 10.12363/issn.1001-1986.24.04.0274
Available at: https://cge.researchcommons.org/journal/vol52/iss10/8

Reference

[1] 王家臣，许家林，杨胜利，等. 煤矿采场岩层运动与控制研究进展：纪念钱鸣高院士“砌体梁”理论40年[J]. 煤炭科学技术，2023，51(1)：80−94.

WANG Jiachen，XU Jialin，YANG Shengli，et al. Development of strata movement and its control in underground mining：In memory of 40 years of Voussoir Beam Theory proposed by Academician Minggao Qian[J]. Coal Science and Technology，2023，51(1)：80−94.

[2] 齐庆新，李一哲，赵善坤，等. 我国煤矿冲击地压发展70年：理论与技术体系的建立与思考[J]. 煤炭科学技术，2019，47(9)：1−40.

QI Qingxin，LI Yizhe，ZHAO Shankun，et al. Seventy years development of coal mine rockburst in China：establishment and consideration of theory and technology system[J]. Coal Science and Technology，2019，47(9)：1−40.

[3] 任智敏，吕梦蛟，王飞，等. 基于钢锥冲击的煤层卸压方法研究[J]. 煤田地质与勘探，2024，52(3)：37−47.

REN Zhimin，LYU Mengjiao，WANG Fei，et al. A method for coal seam pressure relief based on steel cone impact[J]. Coal Geology & Exploration，2024，52(3)：37−47.

[4] 左宇军，李夕兵，张义平. 动静组合加载下的岩石破坏特性[M]. 北京：冶金工业出版社，2008.

[5] 李夕兵. 岩石动力学基础与应用[M]. 北京：科学出版社，2014.

[6] 窦林名，何江，曹安业，等. 煤矿冲击矿压动静载叠加原理及其防治[J]. 煤炭学报，2015，40(7)：1469−1476.

DOU Linming，HE Jiang，CAO Anye，et al. Rock burst prevention methods based on theory of dynamic and static combined load induced in coal mine[J]. Journal of China Coal Society，2015，40(7)：1469−1476.

[7] 何江. 煤矿采动动载对煤岩体的作用及诱冲机理研究[D]. 徐州：中国矿业大学，2013.

HE Jiang. Research of mining dynamic loading effect and its induced rock burst in coal mine[D]. Xuzhou：China University of Mining and Technology，2013.

[8] LI Xibing，ZHOU Zilong，LOK T S，et al. Innovative testing technique of rock subjected to coupled static and dynamic loads[J]. International Journal of Rock Mechanics and Mining Sciences，2008，45(5)：739−748.

[9] 刘少虹，秦子晗，娄金福. 一维动静加载下组合煤岩动态破坏特性的试验分析[J]. 岩石力学与工程学报，2014，33(10)：2064−2075.

LIU Shaohong，QIN Zihan，LOU Jinfu. Experimental study of dynamic failure characteristics of coal-rock compound under one-dimensional static and dynamic loads[J]. Chinese Journal of Rock Mechanics and Engineering，2014，33(10)：2064−2075.

[10] 雷照源，李团结，崔峰，等. 深部厚煤层动静载荷下区段煤柱损伤演化分析[J]. 西安科技大学学报，2022，42(1)：91−98.

LEI Zhaoyuan，LI Tuanjie，CUI Feng，et al. Damage evolution analysis of section coal pillar under dynamic and static load in deep thick coal seam[J]. Journal of Xi’an University of Science and Technology，2022，42(1)：91−98.

[11] 郝志勇，李志伟，潘一山. 冲击倾向性煤层注水对钻进中吸钻卡钻的影响及试验[J]. 煤田地质与勘探，2020，48(3)：231−238.

HAO Zhiyong，LI Zhiwei，PAN Yishan. Influence of water injection in burst-prone coal seam on suction and sticking during drilling[J]. Coal Geology & Exploration，2020，48(3)：231−238.

[12] 满轲，刘晓丽，宗自华，等. 新疆天湖花岗岩的一维动静组合拉伸特性研究[J]. 地下空间与工程学报，2015，11(增刊2)：732−740.

MAN Ke，LIU Xiaoli，ZONG Zihua，et al. Testing study on the one dimensional coupled static and dynamic tension loading for the granite in Xinjiang Tianhu Area[J]. Chinese Journal of Underground Space and Engineering，2015，11(Sup.2)：732−740.

[13] 王文，李化敏，顾合龙. 三维动静组合加载含水煤样强度特征试验研究[J]. 岩石力学与工程学报，2017，36(10)：2406−2414.

WANG Wen，LI Huamin，GU Helong. Experimental study of strength characteristics of water-saturated coal specimens under 3D coupled static-dynamic loadings[J]. Chinese Journal of Rock Mechanics and Engineering，2017，36(10)：2406−2414.

[14] 刘洋，刘长武. 冲击荷载下轴压对峰后破裂砂岩力学特性的影响[J]. 煤炭学报，2018，43(5)：1281−1288.

LIU Yang，LIU Changwu. Effect of axial static stress on mechanical properties of post-peak cracked sandstone under impact loading[J]. Journal of China Coal Society，2018，43(5)：1281−1288.

[15] 潘俊锋，刘少虹，杨磊，等. 动静载作用下煤的动力学特性试验研究[J]. 中国矿业大学学报，2018，47(1)：206−212.

PAN Junfeng，LIU Shaohong，YANG Lei，et al. Experimental study of dynamic characteristics of coal under static and dynamic loads[J]. Journal of China University of Mining & Technology，2018，47(1)：206−212.

[16] 闻磊，梁旭黎，冯文杰，等. 冲击损伤砂岩动静组合加载力学特性研究[J]. 岩土力学，2020，41(11)：3540−3552.

WEN Lei，LIANG Xuli，FENG Wenjie，et al. An investigation of the mechanical properties of sandstone under coupled static and dynamic loading[J]. Rock and Soil Mechanics，2020，41(11)：3540−3552.

[17] YIN Zhiqiang，CHEN Wensu，HAO Hong，et al. Dynamic compressive test of gas-containing coal using a modified split Hopkinson pressure bar system[J]. Rock Mechanics and Rock Engineering，2020，53：815−829.

[18] CHEN Guangqi，HE Manchao，FAN Fusong. Rock burst analysis using DDA numerical simulation[J]. International Journal of Geomechanics，2018，18(3)：04018001.

[19] JIANG Quan，FENG Xiating，XIANG Tianbing，et al. Rockburst characteristics and numerical simulation based on a new energy index：a case study of a tunnel at 2，500 m depth[J]. Bulletin of engineering geology and the environment，2010，69：381−388.

[20] HE Jiang，DOU Linming，MU Zonglong，et al. Numerical simulation study on hard-thick roof inducing rock burst in coal mine[J]. Journal of Central South University，2016，23(9)：2314−2320.

[21] 刘斌. 动静载荷下煤岩冲击失稳机理及多参量前兆规律研究[D]. 北京：中国矿业大学(北京)，2021.

LIU Bin. Study on instability mechanism and multi-parameter precursor law of coal and rock under dynamic and static loads[D]. Beijing：China University of Mining & Technology(Beijing)，2021.

[22] 李夕兵，翁磊，谢晓锋，等. 动静载荷作用下含孔洞硬岩损伤演化的核磁共振特性试验研究[J]. 岩石力学与工程学报，2015，34(10)：1985−1993.

LI Xibing，WENG Lei，XIE Xiaofeng，et al. Study on the degradation of hard rock with a pre-existing opening under static-dynamic loadings using nuclear magnetic resonance technique[J]. Chinese Journal of Rock Mechanics and Engineering，2015，34(10)：1985−1993.

[23] 欧阳振华，孔令海，齐庆新，等. 自震式微震监测技术及其在浅埋煤层动载矿压预测中的应用[J]. 煤炭学报，2018，43(增刊1)：44−51.

OUYANG Zhenhua，KONG Linghai，QI Qingxin，et al. Self-shocking microseismic monitoring technology and its application in prediction of dynamic pressure in shallow coal seam[J]. Journal of China Coal Society，2018，43(Sup.1)：44−51.

[24] LOTIDIS M A，NOMIKOS P P，SOFIANOS A I. Laboratory study of the fracturing process in marble and plaster hollow plates subjected to uniaxial compression by combined acoustic emission and digital image correlation techniques[J]. Rock Mechanics and Rock Engineering，2020，53：1953−1971.

[25] 张凯，张东晓，赵勇强，等. 损伤岩石声发射演化特征及响应机制试验研究[J]. 煤田地质与勘探，2024，52(3)：96−106.

ZHANG Kai，ZHANG Dongxiao，ZHAO Yongqiang，et al. Experimental study on acoustic emission evolution characteristics and response mechanism of damaged rocks[J]. Coal Geology & Exploration，2024，52(3)：96−106.

[26] FUKUI K，OKUBO S，TERASHIMA T. Electromagnetic radiation from rock during uniaxial compression testing：The effects of rock characteristics and test conditions[J]. Rock mechanics and rock engineering，2005，38：411−423.

[27] 周春华，李云安，尹健民，等. 基于微震与电磁辐射联合监测的多元岩爆预警方法研究[J]. 岩土工程学报，2020，42(3)：457−466.

ZHOU Chunhua，LI Yun’an，YIN Jianmin，et al. Multivariate early warning method for rockbursts based on comprehensive microseismic and electromagnetic radiation monitoring[J]. Chinese Journal of Geotechnical Engineering，2020，42(3)：457−466.

[28] 来兴平，刘小明，单鹏飞，等. 采动裂隙煤岩破裂过程热红外辐射异化特征[J]. 采矿与安全工程学报，2019，36(4)：777−785.

LAI Xingping，LIU Xiaoming，SHAN Pengfei，et al. Study on thermal infrared radiation variation of fractured coal-rock mass failure during mining[J]. Journal of Mining & Safety Engineering，2019，36(4)：777−785.

[29] 李忠慧，李明涛，胡棚杰，等. 尺寸效应对岩石单轴压缩试验影响研究[J]. 长江大学学报 (自然科学版)，2024，21(2)：60−66.

LI Zhonghui，LI Mingtao，HU Pengjie，et al. Study on the influence of size effect on rock uniaxial compression test[J]. Journal of Yangtze University (Natural Science Edition)，2024，21(2)：60−66.

[30] 王一伟，刘润，梁超. 小比尺条形基础承载力模型试验的尺寸效应研究[J]. 岩土工程学报，2024，46(6)：1289−1299.

WANG Yiwei，LIU Run，LIANG Chao. Size effects of small-scale model tests on bearing capacity of strip foundation[J]. Chinese Journal of Geotechnical Engineering，2024，46(6)：1289−1299.

[31] VERMA H K，SAMADHIYA N K，SINGH M，et al. Blast induced rock mass damage around tunnels[J]. Tunnelling and Underground Space Technology，2018，71：149−158.

[32] 夏冬，杨天鸿，王培涛，等. 循环加卸载下饱和岩石变形破坏的损伤与能量分析[J]. 东北大学学报 (自然科学版)，2014，35(6)：867−870.

XIA Dong，YANG Tianhong，WANG Peitao，et al. Analysis on damage and energy in deformation and fracture of saturated rock subjected to cyclic loading and unloading[J]. Journal of Northeastern University (Natural Science)，2014，35(6)：867−870.

[33] 徐金海，张晓悟，刘智兵，等. 循环加卸载条件下煤岩组合体力学响应及能量演化规律[J]. 长江科学院院报，2022，39(5)：89−94.

XU Jinhai，ZHANG Xiaowu，LIU Zhibing，et al. Mechanical response and energy evolution law of coal-rock combined specimen under cyclic loading and unloading conditions[J]. Journal of Yangtze River Scientific Research Institute，2022，39(5)：89−94.

[34] LIU Yang，OUYANG Zhenhua，YI Haiyang，et al. Study on the evolutionary characteristics of coal burst proneness under the action of multiple mining disturbances[J]. Energy Science & Engineering，2023，11(10)：3680−3698.