单轴压缩下煤体表面电流试验研究
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摘要
试验研究了在单轴压缩条件下煤体受压产生电流的性质及变化规律,并对产生这种电流变化的原因进行了分析。实验表明,煤在受载破坏过程中,表面有微电流产生。在加载初期,电流产生不明显。当载荷δc≈0.75δmax时,电流开始出现较快增长,并且和载荷的相关系数达0.8~0.9以上,呈高度相关。载荷发生突变或卸压时有较强电流信号出现。根据电流和载荷的对应关系,可以用电流信号来反映煤体受载程度,从而为煤岩体稳定性监测提供一种新的思路。
An investigation was conducted on the characteristics of surface current induced by coal under uniaxial compression.An interpretation of the mechanisms governing the electrical behavior of the coal structures under uniaxial stress tests was presented in this paper.The experimental results show that the current signal is generated during the deformation and fracture process of coal samples.When the load is applied,the electric current makes its initial appearance and increases rapidly after a considerable time lag at δc,until after the stress reaches a value δc≈0.75δmax where δmax is the maximum applied stress before sample fracture.There is a good correlativity between the current and the load,and the correlation coefficient between them can reach up to 0.8 to 0.9.The current peaks occur under sudden loading and unloading.It suggests that the current is closely related to the loading.The status of coal loading level may be determined by the current signal.The intensive study on coal surface current can provide a way for monitoring the stability of coal and rock.
An investigation was conducted on the characteristics of surface current induced by coal under uniaxial compression.An interpretation of the mechanisms governing the electrical behavior of the coal structures under uniaxial stress tests was presented in this paper.The experimental results show that the current signal is generated during the deformation and fracture process of coal samples.When the load is applied,the electric current makes its initial appearance and increases rapidly after a considerable time lag at δc,until after the stress reaches a value δc≈0.75δmax where δmax is the maximum applied stress before sample fracture.There is a good correlativity between the current and the load,and the correlation coefficient between them can reach up to 0.8 to 0.9.The current peaks occur under sudden loading and unloading.It suggests that the current is closely related to the loading.The status of coal loading level may be determined by the current signal.The intensive study on coal surface current can provide a way for monitoring the stability of coal and rock.
引文
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[14]李忠辉,王恩元,何学秋.混凝土断裂表面带电异常研究[J].煤炭学报,2010,35(6):910-914.Li Zhonghui,Wang Enyuan,He Xueqiu.Research on surface elec-tric anomaly of concrete in fracture[J].Journal of China Coal Soci-ety,2010,35(6):910-914.
[15]李艳娜,王恩元,赵恩来.单轴压力下煤样表面电位实验[J].煤炭学报,2009,34(6):806-809.Li Yanna,Wang Enyuan,Zhao Enlai.Experiment on surface poten-tial of coal under uniaxial compression[J].Journal of China CoalSociety,2009,34(6):806-809.
[2]何继善,吕绍林.瓦斯突出地球物理研究[M].北京:煤炭工业出版社,1999:108-111.
[3]王恩元,何学秋,李忠辉,等.煤岩电磁辐射技术及其应用[M].北京:科学出版社,2009.
[4]王恩元,何学秋,聂百胜,等.电磁辐射法预测煤与瓦斯突出原理[J].中国矿业大学学报,2000,29(3):225-229.Wang Enyuan,He Xueqiu,Nie Baisheng,et al.Principle of predic-ting coal and gas outburst using electromagnetic emission[J].Jour-nal of China University of Mining&Technology,2000,29(3):225-229.
[5]王恩元,何学秋,刘贞堂,等.煤岩动力灾害电磁辐射监测仪及其应用[J].煤炭学报,2003,28(4):366-369.Wang Enyuan,He Xueqiu,Liu Zhentang,et al.Electromagnetic radi-ation detector of coal or rockdynamic disasters and its application[J].Journal of China Coal Society,2003,28(4):366-369.
[6]郭自强,周大庄,施行觉,等.岩石破裂中的电子发射[J].地球物理学报,1988,31(5):566-571.Guo Ziqiang,Zhou Dazhuang,Shi Xingjue,et al.Electron emissionduring rock fracture[J].Acta Geophysica Sinica,1988,31(5):566-571.
[7]吴小平,施行觉,郭自强.花岗岩压缩带电的试验研究[J].地球物理学报,1990,33(2):208-211.Wu Xiaoping,Shi Xingjue,Guo Ziqiang.Study of the electrificationof granite samples under compression[J].Acta Geophysica Sinica,1990,33(2):208-211.
[8]郝锦绮,钱书清,高金田,等.岩石破裂过程中的超低频电磁异常[J].地震学报,2003,25(1):102-111.Hao Jinqi,Qian Shuqing,Gao Jintian,et al.Ulf electric and magneticanomalies accompanying the cracking of rock sample[J].Acta Seis-mologica Sinica,2003,25(1):102-111.
[9]郝锦绮,刘力强,龙海丽,等.双轴压力下岩样自电位变化实验的新结果[J].地球物理学报,2004,47(3):475-482.Hao Jinqi,Liu Liqiang,Long Haili,et al.New result of theexperimenton self-potentialchange of rocks under biaxial compression[J].Chi-nese Journal of Geophysics,2004,47(3):475-482.
[10]Takeuchi A,Bobby W S L,Friedemann T F.Current and surfacepotential induced by stress-activated positive holes in igneous rocks[J].Physicsand Chemistry of the Earth,2006,31:240-247.
[11]Anastasiadis C,Triantis D,Hogarth C A.Comments on the phenom-ena underlying pressure stimulated currents in dielectric rock mate-rials[J].J.Mater.Sci.,2007,42:2538-2542.
[12]李忠辉,王恩元,刘贞堂,等.煤岩破坏表面电位特征规律研[J].中国矿业大学学报,2009,38(2):187-192.Li Zhonghui,Wang Enyuan,Liu Zhentang,et al.Study on charac-teristics and rules of surface potential during coal fracture[J].Jour-nal of China University of Mining&Technology,2009,38(2):187-192.
[13]李忠辉,王恩元,谢绍东,等.煤体瓦斯运移诱发电位信号的实验研究[J].煤炭学报,2010,35(9):1481-1485.Li Zhonghui,Wang Enyuan,Xie Shaodong,et al.Experimental re-search on electric potential signals induced by gas flowing in coal[J].Journal of China Coal Society,2010,35(9):1481-1485.
[14]李忠辉,王恩元,何学秋.混凝土断裂表面带电异常研究[J].煤炭学报,2010,35(6):910-914.Li Zhonghui,Wang Enyuan,He Xueqiu.Research on surface elec-tric anomaly of concrete in fracture[J].Journal of China Coal Soci-ety,2010,35(6):910-914.
[15]李艳娜,王恩元,赵恩来.单轴压力下煤样表面电位实验[J].煤炭学报,2009,34(6):806-809.Li Yanna,Wang Enyuan,Zhao Enlai.Experiment on surface poten-tial of coal under uniaxial compression[J].Journal of China CoalSociety,2009,34(6):806-809.
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