Creep acoustic emission and fractal characteristics of coal rock under high temperature pre-damage

Authors

SHI Hongcai, College of Civil Engineering and Environment, Hubei University of Technology, Wuhan 430068, China

Abstract

The thermal damage and triaxial creep acoustic emission experiments of coal samples at different temperatures were carried out to investigate and analyze the mechanical characteristics of coal and rock after high temperature pre-damage. The results show that the thermal damage of coal and rock increases exponentially with the increase of temperature; the brittle-ductile failure characteristics of coal and rock appear at lower temperature(≤200℃) and the accelerated creep characteristics are not obvious; the brittle-brittle failure characteristics of coal and rock appear at higher temperature(＞200℃) and the accelerated creep characteristics are more obvious; the value of steady creep rate is between pre-damage D and pre-damage D. The higher the temperature is, the smaller the acoustic emission ringing counting rate of coal and rock is, the lower the low frequency and low amplitude changes, and the three creep stages tend to develop in the same frequency. The cumulative ringing counts Nm and pre-damage D decrease in a negative exponential function. The fractal dimension values change in three stages with creep test, namely, decrease-dynamic stability-re-decrease with the three creep stages. Correspondingly, the turning point of fractal dimension from steady state to decrease can be used to judge the failure of coal and rock. The higher the temperature(the greater the pre-damage value), the larger the fractal dimension df, the more disorderly the failure of rock sample. The research results are of great significance to reveal the long-term mechanical behavior of coal after pyrolysis and gasification at different temperatures.

Keywords

coal rock, triaxial creep, high temperature pre-damage, acoustic emission ring count, fractal dimension

DOI

10.3969/j.issn.1001-1986.2020.02.028

Recommended Citation

S. (2020) "Creep acoustic emission and fractal characteristics of coal rock under high temperature pre-damage," Coal Geology & Exploration: Vol. 48: Iss. 2, Article 29.
DOI: 10.3969/j.issn.1001-1986.2020.02.028
Available at: https://cge.researchcommons.org/journal/vol48/iss2/29

Reference

[1] 王璐,刘建锋,裴建良,等. 细砂岩破坏全过程渗透性与声发射特征试验研究[J]. 岩石力学与工程学报,2015,34(增刊1):2909-2914. WANG Lu,LIU Jianfeng,PEI Jianliang,et al. Experimental research on permeability and acoustic emission characteristics during whole failure process of fine sandstone[J]. Chinese Journal of Rock Mechanics and Engineering,2015,34(S1):2909-2914.

[2] 谢和平. 分形-岩石力学导论[M]. 北京:科学出版社,1996:1-2. XIE Heping. The introduction of fractal rock mechanics[M]. Beijing:Science Press,1996:1-2.

[3] 杨永杰,陈绍杰,韩国栋. 煤样压缩破坏过程的声发射试验[J]. 煤炭学报,2006,31(5):562-565. YANG Yongjie,CHEN Shaojie,HAN Guodong. Experimental on acoustic emission during compression rupture procedure of coal sample[J]. Journal of China Coal Society,2006,31(5):562-565.

[4] GANNE P,VERVOORT A,WEVERS M. Quantification of pre-peak brittle damage:Correlation between acoustic emission and observed micro-fracturing[J]. International Journal of Rock Mechanics and Mining Science,2007,44(5):720-729.

[5] 陈春谏,赵耀江,郭胜亮,等. 不同含水率煤岩声发射特性试验研究[J]. 煤矿安全,2018,49(5):40-42. CHEN Chunjian,ZHAO Yaojiang,GUO Shengliang,et al. Experimental study on acoustic emission characteristics of coal and rock with different moisture content[J]. Safety in Coal Mines,2018,49(5):40-42.

[6] 高保彬,李回贵,刘云鹏,等. 单轴压缩下煤岩声发射及分形特征研究[J]. 地下空间与工程学报,2013,9(5):986-991. GAO Baobin,LI Huigui,LIU Yunpeng,et al. Study of acoustic emission and fractal characteristics of coal rock under uniaxial compression[J]. Chinese Journal of Underground Space and Engineering,2013,9(5):986-991.

[7] 高保彬,李回贵,于水军,等. 三轴压缩下煤样的声发射及分形特征研究[J]. 力学与实践,2013,35(6):49-54. GAO Baobin,LI Huigui,YU Shuijun,et al. Acoustic emission and fractal characteristics of coal rock samples under triaxial compression[J]. Mechanics and Practice,2013,35(6):49-54.

[8] 高保彬,李回贵,李林,等. 同组软硬煤煤样声发射及分形特征研究[J]. 岩石力学与工程学报,2014,33(增刊2):3498-3504. GAO Baobin,LI Huigui,LI Lin,et al. Study of acoustic emission and fractal characteristics of soft and hard coal samples with same group[J]. Chinese Journal of Rock Mechanics and Engineering,2014,33(S2):3498-3504.

[9] 邵良杉,李永利,孙朋. 煤岩破裂全过程的声发射序列分形特征研究[J]. 中国安全科学学报,2013,23(12):78-83. SHAO Liangshan,LI Yongli,SUN Peng. Study on fractal characteristics of AE sequence of the whole process fracture of coal or rock[J]. Chinese Journal of Safety Sciences,2013,23(12):78-83.

[10] 赵斌,王芝银,伍锦鹏. 煤岩不同应力水平的蠕变及破坏特性[J]. 中国石油大学学报(自然科学版),2013,37(4):140-144. ZHAO Bin,WANG Zhiyin,WU Jinpeng. Creep and damage characteristics of coal rock under different stress[J]. Journal of China University of Petroleum(Natural Science Edition),2013,37(4):140-144.

[11] 秦虎,黄滚,贾泉敏. 含瓦斯煤岩卸围压声发射特性及能量特征分析[J]. 煤田地质与勘探,2015,43(5):86-89. QIN Hu,HUANG Gun,JIA Quanmin. Analysis of acoustic emission characteristics and energy characteristics of gas-bearing coal and rock under unloading confining pressure[J]. Coal Geology & Exploration,2015,43(5):86-89.

[12] 杨永杰,王德超,赵南南,等. 煤岩蠕变声发射特征试验研究[J]. 应用基础与工程科学学报,2013,21(1):159-166. YANG Yongjie,WANG Dechao,ZHAO Nannan,et al. Acoustic emission characteristics of coal creep under step load[J]. Journal of Basic Science and Engineering,2013,21(1):159-166.

[13] 李鹏. 煤岩渗流-蠕变耦合作用下声发射试验研究[J]. 矿业安全与环保,2017,44(4):19-23. LI Peng. Experimental study on acoustic emission of coal and rock under seepage-creep coupling action[J]. Mining Safety and Environmental Protection,2017,44(4):19-23.

[14] 费金彪,文虎,张铎. 补连塔矿2-2煤高温热解机理TG/DSC-FTIR-MS/GC研究[J]. 煤炭技术,2018,37(1):301-304. FEI Jinbiao,WEN Hu,ZHANG Duo. Study on pyrolysis mechanism of 2-2 coal in Bulianta coal mine based on TG/DSC-FTIR-MS/GC[J]. Coal Technology,2018,37(1):301-304.

[15] 郑则用. 褐煤高温受热变质产气及突出试验研究[D]. 焦作:河南理工大学,2017. ZHENG Zeyong. Experimental study on gas production and outburst of Lignite by high temperature metamorphism[D]. Jiaozuo:Henan Polytechnic University,2017.

[16] 邓军,宋佳佳,赵婧昱,等. 高温氧化条件下风化煤自燃特性试验研究[J]. 煤炭科学技术,2017,45(1):73-77. DENG Jun,SONG Jiajia,ZHAO Jingyu,et al. Experiment study on spontaneous combustion features of weathered coal under condition of high temperature oxidation[J]. Coal Science and Technology,2017,45(1):73-77.

[17] 周长冰,万志军,张源,等. 高温三轴应力下气煤蠕变特征及本构模型[J]. 煤炭学报,2012,37(12):2020-2025. ZHOU Changbing,WAN Zhijun,ZHANG Yuan,et al. Creep characteristics and constitutive model of gas-coal mass under high temperature and triaxial stress[J]. Journal of China Coal Society,2012,37(12):2020-2025.

[18] 崔丽萍,蔡会武. 粒度和升温速率对黄陵煤热解动力学的影响[J]. 应用化工,2016,45(增刊2):201-204. CUI Liping,CAI Huiwu. Particle size and heating rate on the pyrolysis kinetics of Huangling coal[J]. Applied Chemical Industry,2016,45(S2):201-204.

[19] 王晋伟. 升温速率对煤热解特性的影响[J]. 山西煤炭,2010,30(11):66-67. WANG Jinwei. Influence of heating rate on coal pyrolysis characteristics[J]. Shanxi Coal,2010,30(11):66-67.

[20] 吴春,郭棋武,洪涛,等. 基于超声检测的软岩单轴流变损伤试验[J]. 煤田地质与勘探,2017,45(5):105-111. WU Chun,GUO Qiwu,HONG Tao,et al. Uniaxial rheological damage experiment of soft rock based on the ultrasonic testing[J]. Coal Geology & Exploration,2017,45(5):105-111.

[21] 赵阿兴. 岩石软化温度及其在地球深部岩石力学性质研究中的意义[J]. 地球物理学进展,1993,8(2):94-100. ZHAO Axing. The softening temperature of rocks and its implication in rock mechanics of earth's deep interior[J]. Progress in Geophysics,1993,8(2):94-100.

[22] 赵亚永,魏凯,周佳庆,等. 三类岩石热损伤力学特性的试验研究与细观力学分析[J]. 岩石力学与工程学报,2017,36(1):142-151. ZHAO Yayong,WEI Kai,ZHOU Jiaqing,et al. Laboratory study and micromechanical analysis of mechanical behaviors of three thermally damaged rocks[J]. Chinese Journal of Rock Mechanics and Engineering,2017,36(1):142-151.

[23] XIE Heping,WANG Jin'an,XIE Weihong. Fractal effects of surface roughness on the mechanical behavior of rock joints[J]. Chaos,Solitons & Fractals,1997,8(2):221-252.

[24] 张亚衡,周宏伟,谢和平. 粗糙表面分形维数估算的改进立方体覆盖法[J]. 岩石力学与工程学报,2005,24(17):3192-3196. ZHANG Yaheng,ZHOU Hongwei,XIE Heping. Improved cubic covering method for fractal dimension of a fracture surface of rock[J]. Chinese Journal of Rock Mechanics and Engineering,2005,24(17):3192-3196.