基于全波形的煤样单轴压缩破坏声电时频特征
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摘要
建立了煤岩受载破坏声电全波形同步采集系统,对煤样单轴压缩破坏过程中的声电信号进行了全波形采集,研究了声电信号能量与载荷降之间的相关关系,并分析了声电信号的频谱特征.结果表明:(1)煤体受载破坏过程中产生显著的声电信号;电磁辐射信号是阵发性的,仅伴随载荷降和较高强度声发射信号出现;(2)相对于声发射,电磁辐射与载荷降有更好的相关性;与煤体受载破坏的能量释放累积量相关联的声电信号能量和载荷降累计值三者之间均呈高度正相关;(3)电磁辐射优势频带窄于声发射,前者主要集中在1～25 kHz,后者主要集中在1～280 kHz;受同一裂纹萌生和扩展的影响,两者在频谱和主频分布上都有近似的低频成分.
The geological conditions of coal mines in China are complicated. In recent years,with the continuous increase of intensity and depth of coal mining,coal and rock dynamic disasters are becoming more and more serious,and an important factor threatening the safety of coal mining. The accurate monitoring and early warning of coal and rock dynamic disasters are of great significance for disaster prevention. A large number of experiments conducted on both laboratory and field scales have demonstrated that the energy accumulated in rock material under loading can be released in the forms of acoustic emission( AE),electromagnetic radiation( EMR),etc. Therefore,AE and EMR,as the real-time,dynamic and continuous geophysical monitoring methods,have been widely used and played important roles in the field of monitoring and early-warning of coal and rock dynamic disasters in mines. To further study the time-frequency characteristics of AE and EMR and the relationships between these characteristics and load,and to provide the experimental basis for the monitoring and early warning of coal and rock dynamic disasters,an acoustic-electric full-waveform synchronous acquisition system of coal and rock fracture under loading was constructed in this paper. Using this system,the full-waveforms of AE and EMR of failure processes of coal samples under uniaxial compression were collected. The correlations among AE energy,EMR energy and load drop were studied,and the spectral characteristics of AE and EMR were analyzed. The results show that,( 1) obvious acoustic-electric signals are emitted during the process of coal failure under loading. EMR is the paroxysmal signal,only accompanied by load drop and higher intensity AE.( 2) Compared with AE,EMR has a higher correlation with load drop. There are high positive correlations among the cumulative values,relating to the cumulative released energy of coal fracture under loading,of AE energy,EMR energy and load drop.( 3) The superiority frequency band of EMR is narrower than that of AE,with the former mainly concentrated in 1-25 k Hz and the latter mainly in 1-280 k Hz. Influenced by the initiation and propagation of the same crack,AE and EMR have similar low frequency components in the spectrum and main-frequency distribution.
The geological conditions of coal mines in China are complicated. In recent years,with the continuous increase of intensity and depth of coal mining,coal and rock dynamic disasters are becoming more and more serious,and an important factor threatening the safety of coal mining. The accurate monitoring and early warning of coal and rock dynamic disasters are of great significance for disaster prevention. A large number of experiments conducted on both laboratory and field scales have demonstrated that the energy accumulated in rock material under loading can be released in the forms of acoustic emission( AE),electromagnetic radiation( EMR),etc. Therefore,AE and EMR,as the real-time,dynamic and continuous geophysical monitoring methods,have been widely used and played important roles in the field of monitoring and early-warning of coal and rock dynamic disasters in mines. To further study the time-frequency characteristics of AE and EMR and the relationships between these characteristics and load,and to provide the experimental basis for the monitoring and early warning of coal and rock dynamic disasters,an acoustic-electric full-waveform synchronous acquisition system of coal and rock fracture under loading was constructed in this paper. Using this system,the full-waveforms of AE and EMR of failure processes of coal samples under uniaxial compression were collected. The correlations among AE energy,EMR energy and load drop were studied,and the spectral characteristics of AE and EMR were analyzed. The results show that,( 1) obvious acoustic-electric signals are emitted during the process of coal failure under loading. EMR is the paroxysmal signal,only accompanied by load drop and higher intensity AE.( 2) Compared with AE,EMR has a higher correlation with load drop. There are high positive correlations among the cumulative values,relating to the cumulative released energy of coal fracture under loading,of AE energy,EMR energy and load drop.( 3) The superiority frequency band of EMR is narrower than that of AE,with the former mainly concentrated in 1-25 k Hz and the latter mainly in 1-280 k Hz. Influenced by the initiation and propagation of the same crack,AE and EMR have similar low frequency components in the spectrum and main-frequency distribution.
引文
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[2]Li Z H,Lou Q,Wang E Y,et al.Experimental study of acousticelectric and thermal infrared characteristics of roof rock failure.JChina Univ Min Technol,2016,45(6):1098(李忠辉,娄全,王恩元,等.顶板岩石受压破坏过程中声电热效应研究.中国矿业大学学报,2016,45(6):1098)
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[9]Liu J H,Zhao L,Song S M,et al.Ultrasonic velocity and acoustic emission properties of concrete eroded by sulfate and its damage mechanism.Chin J Eng,2016,38(8):1075(刘娟红,赵力,宋少民,等.混凝土硫酸盐腐蚀损伤的声波与声发射变化特征及机理.工程科学学报,2016,38(8):1075)
[10]Zhang J,Chai M Y,Xiang J H,et al.Fatigue damage evaluation of 316LN stainless steel using acoustic emission monitoring.Chin J Eng,2017,40(4):461(张进,柴孟瑜,项靖海,等.基于声发射监测的316LN不锈钢的疲劳损伤评价.工程科学学报,2017,40(4):461)
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[12]Wang E Y,He X Q,Liu X F,et al.A non-contact mine pressure evaluation method by electromagnetic radiation.J Appl Geophys,2011,75(2):338
[13]Wang E Y,He X Q,Liu X F,et al.Comprehensive monitoring technique based on electromagnetic radiation and its applications to mine pressure.Safety Sci,2012,50(4):885
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[15]Rabinovitch A,Frid V,Bahat D.Surface oscillations-a possible source of fracture induced electromagnetic radiation.Tectonophysics,2007,431(1-4):15
[16]Rabinovitch A,Frid V,Bahat D.Directionality of electromagnetic radiation from fractures.Int J Fract,2017,204(2):239
[17]Li X B,Wan G X,Zhou Z L.The relation between the frequency of electromagnetic radiation(EMR)induced by rock fracture and attribute parameters of rock masses.Chin J Geophys,2009,52(1):253(李夕兵,万国香,周子龙.岩石破裂电磁辐射频率与岩石属性参数的关系.地球物理学报,2009,52(1):253)
[18]Zhao Y X,Jiang Y D.Acoustic emission and thermal infrared precursors associated with bump-prone coal failure.Int J Coal Geol,2010,83(1):11
[19]Zhao Y F,Pan Y S,Liu Y C,et al.Experimental study of charge induction of coal samples under uniaxial compression.Chin J Rock Mech Eng,2011,30(2):306(赵扬锋,潘一山,刘玉春,等.单轴压缩条件下煤样电荷感应试验研究.岩石力学与工程学报,2011,30(2):306)
[20]Potirakis S M,Karadimitrakis A,Eftaxias K.Natural time analysis of critical phenomena:the case of pre-fracture electromagnetic emissions.Chaos,2013,23(2):023117-1
[21]Potirakis S M,Mastrogiannis D.Critical features revealed in acoustic and electromagnetic emissions during fracture experiments on Li F.Physica A,2017,485:11
[22]Gade S O,Weiss U,Peter M A,et al.Relation of electromagnetic emission and crack dynamics in epoxy resin materials.JNondestruct Eval,2014,33(4):711
[23]Gade S O,Alaca B B,Sause M G R.Determination of crack surface orientation in carbon fibre reinforced polymers by measuring electromagnetic emission.J Nondestruct Eval,2017,36:21
[24]Carpinteri A,Lacidogna G,Borla O,et al.Electromagnetic and neutron emissions from brittle rocks failure:experimental evidence and geological implications.Sādhanā,2012,37(1):59
[25]Zhu T,Zhou J G,Wang H Q.Electromagnetic emissions during dilating fracture of a rock.J Asian Earth Sci,2013,73:252
[26]Ohnaka M,Mogi K.Frequency characteristics of acoustic emission in rocks under uniaxial compression and its relation to the fracturing process to failure.J Geophys Res,1982,87(B5):3873
[2]Li Z H,Lou Q,Wang E Y,et al.Experimental study of acousticelectric and thermal infrared characteristics of roof rock failure.JChina Univ Min Technol,2016,45(6):1098(李忠辉,娄全,王恩元,等.顶板岩石受压破坏过程中声电热效应研究.中国矿业大学学报,2016,45(6):1098)
[3]Mastrogiannis D,Antsygina T N,Chishko K A,et al.Relationship between electromagnetic and acoustic emissions in deformed piezoelectric media:microcracking signals.Int J Solids Struct,2015,56-57:118
[4]Song D Z,Wang E Y,Song X Y,et al.Changes in frequency of electromagnetic radiation from loaded coal rock.Rock Mech Rock Eng,2016,49(1):291
[5]Carpinteri A,Lacidogna G,Pugno N.Structural damage diagnosis and life-time assessment by acoustic emission monitoring.Eng Fract Mech,2007,74(1-2):273
[6]Wang E Y,He X Q,Li Z H,et al.Electromagnetic Radiation Technology of Coal and Rock and Its Application.1st Ed.Beijing:Science Press,2009(王恩元,何学秋,李忠辉,等.煤岩电磁辐射技术及其应用.1版.北京:科学出版社,2009)
[7]Donner R V,Potirakis S M,Balasis G,et al.Temporal correlation patterns in pre-seismic electromagnetic emissions reveal distinct complexity profiles prior to major earthquakes.Phys Chem Earth Part A/B/C,2015,85-86:44
[8]He X Q,Dou L M,Mu Z L,et al.Continuous monitoring and warning theory and technology of rock burst dynamic disaster of coal.J China Coal Soc,2014,39(8):1485(何学秋,窦林名,牟宗龙,等.煤岩冲击动力灾害连续监测预警理论与技术.煤炭学报,2014,39(8):1485)
[9]Liu J H,Zhao L,Song S M,et al.Ultrasonic velocity and acoustic emission properties of concrete eroded by sulfate and its damage mechanism.Chin J Eng,2016,38(8):1075(刘娟红,赵力,宋少民,等.混凝土硫酸盐腐蚀损伤的声波与声发射变化特征及机理.工程科学学报,2016,38(8):1075)
[10]Zhang J,Chai M Y,Xiang J H,et al.Fatigue damage evaluation of 316LN stainless steel using acoustic emission monitoring.Chin J Eng,2017,40(4):461(张进,柴孟瑜,项靖海,等.基于声发射监测的316LN不锈钢的疲劳损伤评价.工程科学学报,2017,40(4):461)
[11]Niccolini G,Xu J,Manuello A,et al.Onset time determination of acoustic and electromagnetic emission during rock fracture.Prog Electromagn Res Lett,2012,35:51
[12]Wang E Y,He X Q,Liu X F,et al.A non-contact mine pressure evaluation method by electromagnetic radiation.J Appl Geophys,2011,75(2):338
[13]Wang E Y,He X Q,Liu X F,et al.Comprehensive monitoring technique based on electromagnetic radiation and its applications to mine pressure.Safety Sci,2012,50(4):885
[14]Frid V,Vozoff K.Electromagnetic radiation induced by mining rock failure.Int J Coal Geol,2005,64(1-2):57
[15]Rabinovitch A,Frid V,Bahat D.Surface oscillations-a possible source of fracture induced electromagnetic radiation.Tectonophysics,2007,431(1-4):15
[16]Rabinovitch A,Frid V,Bahat D.Directionality of electromagnetic radiation from fractures.Int J Fract,2017,204(2):239
[17]Li X B,Wan G X,Zhou Z L.The relation between the frequency of electromagnetic radiation(EMR)induced by rock fracture and attribute parameters of rock masses.Chin J Geophys,2009,52(1):253(李夕兵,万国香,周子龙.岩石破裂电磁辐射频率与岩石属性参数的关系.地球物理学报,2009,52(1):253)
[18]Zhao Y X,Jiang Y D.Acoustic emission and thermal infrared precursors associated with bump-prone coal failure.Int J Coal Geol,2010,83(1):11
[19]Zhao Y F,Pan Y S,Liu Y C,et al.Experimental study of charge induction of coal samples under uniaxial compression.Chin J Rock Mech Eng,2011,30(2):306(赵扬锋,潘一山,刘玉春,等.单轴压缩条件下煤样电荷感应试验研究.岩石力学与工程学报,2011,30(2):306)
[20]Potirakis S M,Karadimitrakis A,Eftaxias K.Natural time analysis of critical phenomena:the case of pre-fracture electromagnetic emissions.Chaos,2013,23(2):023117-1
[21]Potirakis S M,Mastrogiannis D.Critical features revealed in acoustic and electromagnetic emissions during fracture experiments on Li F.Physica A,2017,485:11
[22]Gade S O,Weiss U,Peter M A,et al.Relation of electromagnetic emission and crack dynamics in epoxy resin materials.JNondestruct Eval,2014,33(4):711
[23]Gade S O,Alaca B B,Sause M G R.Determination of crack surface orientation in carbon fibre reinforced polymers by measuring electromagnetic emission.J Nondestruct Eval,2017,36:21
[24]Carpinteri A,Lacidogna G,Borla O,et al.Electromagnetic and neutron emissions from brittle rocks failure:experimental evidence and geological implications.Sādhanā,2012,37(1):59
[25]Zhu T,Zhou J G,Wang H Q.Electromagnetic emissions during dilating fracture of a rock.J Asian Earth Sci,2013,73:252
[26]Ohnaka M,Mogi K.Frequency characteristics of acoustic emission in rocks under uniaxial compression and its relation to the fracturing process to failure.J Geophys Res,1982,87(B5):3873