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英文原文EME rock burst monitoring in coal mine huafeng(Dou lin ming ，china university of mining and technology, Xu fangjun,Zhang xiufeng，huafeng mine,shan dong, china)AbstractThe electromagnetic emission is caused by the inhomogeneous variable speed and the deformation of various parts of the coal and the variable speeding movement of electrical particles during crack expansion. This article is about the EME rules before and after the coal sample failure in 4# coal seam of HuaFeng mine by experiments. some methods to monitor and forecast .KBD5 apparatus has been used to monitor the 4# coal seam which has high danger of burst in Huafeng mine, many times rock pressure were forecasted according to the EME rules. Therefore EME technique can be applied in coal mines.1 EME mechanism of rock burst failure1.1 EME Mechanism of Rock Burst FailureThe research shows that the EME is the result of the deformation and the failure of the loaded inhomogeneous materials, such as coal and rock, and is formed in the variable speeding movement of electrical particles during crack expansion caused by the inhomogeneous variable speed and the deformation of various parts of the coal.Variable deformation of various parts of the variously loaded coal and rock makes the free and escaping electrons move from the high-stress zones to the low-stress zones. At the same time, a lot of charges are covering the coal samples surface, thus coulombs field or low frequency EME comes into being. Before the crack expands, there are a great number of charges or electrons on it. After the crack expansion, parts of the coal around the crack contract, meantime the Coulombs field is formed because of the high concentration of electrons are accelerated with EME radiated. EME are ionized.1.2 EME Phenomena and Experiment Result of Rock BurstThe EME characteristic of HuaFeng coal was described by the experiment in lab. Fig 1 represents the typical curves of the stress distribution, EME impulse distribution and EME amplitude distribution of HuaFeng coal sample, which has high danger of Rock Burst.From the experiment results we know that EME signals appear in the process of deformation and failure udder loading the various coal and rock. EME amplitude is below a certain value before the brittle failure, while it suddenly increase of loading and the rate of deformation in coal. EME amplitude is below a certain value before the brittle failure, while it suddenly increases during the brittle failure of the loaded coal sample.If the 80% of the maximum failure stress of the coal sample is considered as the warning EME value of Rock Burst, then it can be figured out on the basis of EME experiment. Thewarning EME value of Rock Burst of the 4# coal seam in HuaFeng Mine are listed as Tab 1 shows:Tab 1The warning EME value of Rock BurstCoal seamThe stress value of brittlefailure/MpaThe EME value of coal failureMaximumWarning valueAmplitude/mvImpulsemaximumWarning valuemaximumWarning value4#16.112.9433346610488a. The relationship between EAE load and time of 5# coal sampleb. The relationship between EAE amplitude and time of 5#coal samplec. The relationship between EAE impulse and time of 5#coal sample Fig.1 the result of coal sample experimentThe experiment results show EME impulse basically increased with the increase of loading and the rate of deformation in coal. The higher the stress and the rate of deformation are, the stronger the EME signal is.2 forecastinf of rock burst2.1 The principle of EMEs forecasting Rock BurstThe coal on the working face is in an unstable state when its stress balance is broken after the heading and working space has been formed. There is EME radiated in the process of the rib coals deformation and cracks forming to have a new stress balance, causing the coal to deform and to crack.The higher the stress in the coal is , the stronger the EME value is. The higher the EME frequency is, the greater the danger of Rock Burst is. From the low-stress zone to the high-stress zone with the working face advancement, the EME signal is becoming stronger. In the abutment area, the stress sis the highest, and the deformation of the coal is also great, therefore the EME signal is the strongest. In the low-stress zone, the EME amplitude decrease and intends to the balance. The EME signal received by isolated way is a collectivity of the ones if both low-stress zone and high-stress zone. When the stress in the monitored zone is high ,the EME signal gives the just character of high stress zone, therefore we can use the EME signal to describe the high stress zone and then forecast the Rock Burst.The research of the on-site test and the analysis in theory all shows that the deformation value-(t) vary with EME amplitude and impulse. Before the Rock Burst, the EME value is higher, then it decreases, bur during this period of time the value reaches or exceeds critical value. The change of the EME value and impulse reflects the process of the failures growth.2.2 Methods of the Forecasting Rock Burst2.2.1 The EME parametersThe EME maximum amplitude, the average amplitude and the impulse is applied for describing high-stress zone in coal seam.2.2.2 Method of the forecasting Rock BurstThe EME critical point, deviation values, fractal character can be used to forecast the Rock Burst.The EME critical point is a method that 1.5 average values measured on the place where there is mo danger of coal failure or in normal condition are considered as the critical values. When the EME value monitored exceeds the critical value, the danger of rock burst increases. The formula is:Ecri=1.5EaveEME Fractal character is a method of analysis of fractal dimension of the EME data by time. Practice proves that under normal conditions the change of fractal dimension of the EME value is small, but before or after the rock burst, it much changes. When this change is from little to much of from much to little, it has high danger of Rock Burst when mining.D=(E-Eave)/Eave100%2.2.3 The principle of the forecastingThe factors influencing the Rock Burst include geography conditions, mining technology and so on. Based on kinds of factors influence on Rock Burst, the danger classification of rock burst is decided.Tab 2 The classification of Rock BurstDanger classification Of Rock BurstDanger state of Rock burstDanger index of Rock BurstANo danger0.25BWeak danger0.250.5CMiddle danger0.50.75DGreat danger0.750.95Eunsafe0.953 Application of the eme technique3.1 The Condition of the Tested Working FaceEME technique was used in Huafeng Mine on 3406(1) working face, which is located in District 2 of mining area 3 of layer 4 at level-750m. Seam 4 which is 6.5m thick has high danger of Rock Burst. It has 3 layers, the first layer is 2.2m thick, and its dip angle is 34.3406(1) working face is neighbored by Fault 51 pillar in the west and Mining areas 2 separating pillar in the east. Below the working face 3406 is the virgin coal seam, and above if is the goal of mining area3 at level 3. the air road2ay is 537m above the sea level, the drawing roadway 616m, the stride length of working face is 650m. The immediate roof is siltstone with the thickness of 2.0m.3.2 The KBD5 apparatusKBD5 apparatus is used to monitored the EME on the working face, in the way of non-touched directional testing, accepting, accepting a wide range of frequency to the top of 500HZ, testing a distance from 7m to 22m, and the tested point is 10m far from each other.3.3 Application of the EME TechniqueThe research show the change of the EME on the tested working face and in the roadway is usually small, and there is less EME impulse. The EME amplitude in different area of the working face is different. It is high where the pressure and the danger of Rock burst is high. There are obvious signs of the greatly after the reliving shot. This proves that there is great deformation in the coal wall, it is very likely to have Rock Burst.Fig3 is about the results of the EME of the middle of the 3406(1) working face.Fig4 is about the regularity of the fractal character of the three features. Fig 5 is about the regularity of the deviation values of the three features parameters. According to these figures, the three feature parameters have all exceeded the critical value before the Rock Burst.Fig.3 The Regularity of the EME Amplitude Before and after Rock BurstFig.4 The relationship between the EME fractal dimension and time of 130th prop of the working faceFig.5 The change of EME deviation of 130th prop of the working face3.4 The EME Forecasting Guideline of Rock Burst on the Working FaceAccording to many times of EME practice, the EME forecasting guideline of Rock Burst on the 3406(1) working face is decided. Tab 3 shows the forecasting guideline in the way of critical point and deviation value.Tab 3. The forecasting guideline of Rock BurstMaximum amplitudeAverage amplitudeImpulseCritical point17310422Deviation value35%15%150%We have successfully forecasted many times of Rock Burst by using the guideline, and protected us from many accidents.3.5 EME Forecasting AccuracyIf the monitored Rock BURST C is considered as the forecasting the 1.0 or above vibration and rock burst is 100%. If Rock Burst D is considered as the forecasting criterion, the accuracy is 73%.4 conclusions(1) EME signals appear in the process of deformation and failure under loading the coal and rock. EME basically grows stronger with the increase of loading and the rate of deformation in coal.(2) EME amplitude is below a certain value before the brittle failure, while it suddenly increases during the brittle failure of the loaded coal sample. EME impulse is increased with the increase of the load and the deformation.(3) The of-site practice shows that the maximum EME amplitude, average amplitude and the impulse increase with the increase of the danger of rock burst. The EME character of different state of working face and the forecasting guideline cha forecast many times of rock burst.(4) If the monitored rock burst C is considered as the forecasting criterion, the accuracy of forecasting the 1.0 of above vibration and ROCK BURST is 100%.References1 Dou Lin ming, He xue qiu burst control theory and technology, China Mining University Press, 20012 Dou Lin ming Electromagnetic radiation and acoustic emission in coal and rock burst on the application PhD thesis, China University of Mining, 2001,33 Dou lin ming,Hexueqiu coal electromagnetic radiation when the rock mass failure of Tsinghua University,December 2001 414 Dou Lin ming, He xue qiu: Rock Burst Control Theory and Technology, China Mining University Press, 20015 Fang huan ming: burst of production of the mine and its prevention, Coal Library, 20026 Wang sheng shen: Mine Disaster Control Theory and Technology, China Mining University Press, 19897 Jiang guo an, Lv jia li: Mining Engineering English, 19988 The National Natural Science Terminology Committee: Coal Science and Technology Foundation, 19969 ChenyanGuang, Xu yong qi: Chinas coal mining approach, China Mining University Press, 199110 Feng chang rong: Coal Mine Mining Design Manual, Coal Industry Press, 198411 Feng chang rong: Mining Engineering graduate design guidance, China Mining University Press, 1996中文译文华丰煤矿冲击矿压电磁辐射监测窦林名 1，徐方军 2，张秀峰 2（1.中国矿业大学；2.中国山东华丰煤矿）摘要电磁辐射是由煤的裂缝在扩大的过程中，变速运动和不同部分的变形以及电子变速运动引起的。这篇论文是关于华丰煤矿 4#煤层破坏前后的电磁辐射实验结果。一些关键的、有价值的监测和预报冲击矿压的方法已经被认可。KBD5 装置已经被用来监测华丰煤矿有高冲击矿压的 4#煤层。多次预报的冲击矿压同电磁辐射 规律完全一致。因此，电磁辐射技术能被用在煤矿中。1 冲击矿压的电磁辐射机理1.1 冲击矿压的电磁辐射机理研究表明电磁辐射是煤岩体非均匀物质在加载过程中变形破坏引起的，是在裂缝扩大过程中由变速运动和煤不同部分变形引起电子变速运动形成的。不同部分受到不同载荷引起不同的变形，煤岩使自由电子由高压区移到低压区。同时， 大量的电子积聚在煤样表面，因此，在库仑力的作用下，低频率的电磁辐射就产生了，在裂缝扩大之前，大量的电子在样品上，在裂缝变速扩大的过程中，电子被释放出，电磁辐射和声发射同时放出。在裂缝扩大后，部分集中在裂缝的四周，同时，由于电子高度集中在裂缝的两边，库仑力形成了。库仑力的影响下，自由电子运动加速了电磁辐射。当分子和原子被减速、被电离时，电磁辐射被放出。1.2 冲击矿压的电磁辐射现象和实验结果下面是实验室测试的华丰煤矿煤样的电磁辐射特征。图 1 为华丰矿 5#煤样的典型应力时间、电磁辐射脉冲数时间、电磁辐射幅值时间的曲线图。从实验结果得到，5# 煤层有很高的冲击矿压危险性。从实验结果我们可以得出：不同类型的煤岩体在载荷作用下变形及破坏过程中都有电磁辐射信号产生。电磁辐射基本上随着载荷的增加而增加。在加载煤样发生冲击破坏之前， 电磁辐射幅值总低于一个特定值，而在冲击破坏时，电磁辐射幅值会突然增加。（a）5#煤层煤样变形破坏的 PT 曲线图（b） 5#煤层煤样电磁辐射幅值时间曲线图（c） 5#煤层煤样电磁辐射脉冲数时间曲线图图 1 煤样实验结果根据电磁辐射实验，假如煤样破坏最大压力的 80%作为冲击破坏的预警值，表 1 列出了华丰煤矿 4#煤层电磁辐射值与岩体冲击破坏预警值。表 1电磁辐射值与冲击破坏预警值煤层冲击破坏力/MPa煤冲击破坏时的电磁辐射值最大值预警值幅值/mv脉冲数最大值预警值最大值预警值4#16.112.9433346610488实验结果表明：煤体电磁辐射脉冲数随着载荷的增大及变形速度的增强而增大，载荷越大，加载速度越大，煤样的变形破坏越强烈，电磁辐射信号越强。2 冲击矿压的预报2.1 电磁辐射预报冲击矿压的原则在工作面形成之后，工作面煤的压力平衡状态被打破了，处在一种不平衡状态，在煤变形和断裂形成新的压力平衡过程中，电磁辐射被防出。煤中压力越高，电磁辐射值越高。电磁辐射频率越高，发生冲击矿压的危险性就越高。随着工作面的推进，由低应力区到高应力区，电磁辐射信号变得更加强烈。在临近区，压力最高，煤的变形最大，因此，电磁辐射信号最强。在低应力区，电磁辐射幅值减小，趋于平衡。通过隔离方法，收集低应力区与高应力区的电磁辐射信号，当监测区的应力增大时，电磁辐射信号正好提供了高应力区的特征。因此，我们可以用电磁辐射信号来监测高应力区和预报冲击矿压。通过现场观测和理论分析发现变形值（t）和变形能W（t）与电磁辐射幅值、脉冲数并不一致。在冲击破坏之前，电磁辐射值非常高，接着降低。但是在这一阶段，电磁辐射只会达到或超过临界值，电磁辐射幅值和电磁辐射频率的改变，反映了煤岩逐步破坏的过程。2.2 冲击矿压预报方法2.2.1 电磁辐射参数电磁辐射最大幅值、平均幅值和脉冲数被用来描述煤层高压力区。2.2.2 预报冲击矿压的方法电磁辐射临界点，偏差值，不连续特征能被用来预报冲击矿压。电磁辐射临界点是在煤还没有破坏危险或自然条件下测得的平均值的 1.5 倍，当电磁辐射监测值超过临界点，冲击矿压的危险性就会增加。公式为：Ecri=1.5Eave磁辐射不连续特征是分析电磁辐射数据随时间而变化的一种方法，实践证明了，在自然条件下电磁辐射不连续值是很小的，但是，在冲击矿压发生前后，它会发生巨大的变化， 当这变化由小变大，或由大变小，在采矿过程中就会有冲击矿压发生的危险。电磁辐射偏差值是通过分析平均值和检测值之间的不同，来预报冲击矿压的一种方法。实践证明在冲击矿压发生前偏差值变化非常大。公式为：D=(E-Eave)/Eave100%2.2.3 预报原则地质条件、采矿工艺等多方面的因素影响了冲击矿压。根据影响冲击矿压的因素，规定了冲击矿压危险性等级。表 2冲击矿压等级冲击矿压等级冲击矿压危险性状态冲击矿压指标A没有危险0.25B有危险0.250.5C中等危险0.50.75D非常危险0.750.95E不安全0.953 电磁辐射技术的应用3.1 被测工作面的地质条件电磁辐射技术被用在华丰煤矿 3406（1）工作面，3402 工作面位于-750 水平，3 采区2 区段 4#煤层。4#煤层厚 6.5m，有高冲击矿压危险性。它有三个分层，第一层是 2.2m 厚， 角度为 34，3406（1）工作面的西边是遗留下的 51 个煤柱，和东边 2 采区的煤柱。3406（1）工作面下面是未开采煤层，在它的上面 3 水平 3 采区。回风巷标高-537m，运输巷标高-616m，工作面走向长度 650m。直接顶是厚 2.0m 的泥岩。3.2 KBD5 装置KBD5 装置被用来监测工作面的电磁辐射幅值，通过非接触直接测试最高范围到 500赫兹的电磁辐射。测试距离从 7m 到 22m，每个测点之间的距离都在十米以上。3.3 电磁辐射技术的应用研究表明被测工作面和巷道的电磁辐射通常变化非常小，很少有电磁辐射脉冲。在工作面不同位置，电磁辐射幅值不同，压力越高，冲击矿压的危险性越高，电磁辐射幅值越高。在发生冲击矿压之前，电磁辐射幅值电磁辐射脉冲数快速增加，这是要发生冲击矿压的信号。冲击矿压再一次发生时，电磁辐射脉冲又巨大变化。这证明了在煤壁中发生了巨大变形，很有可能发生了冲击矿压。图 3 是 3406（1）工作面中部的电磁辐射结果。图 4 是电磁辐射不完整特征的三个规律。图 5 是电磁辐射偏差值的三个特征参数规律。根据这些图，在冲击矿压发生前，三个特征参数都超过临界值，它们的偏差值，不连续值变化很大，因此，用电磁辐射技术和其它方法能很大提高预测冲击矿压的准确性。图 3冲击矿压前后电磁辐射脉冲规律图 4工作面 130 支柱电磁辐射不连续关系图 5电磁辐射偏差值3.4 电磁辐射预报工作面冲击矿压指标根据多次的电磁辐射实验，规定了 3406（1）工作面冲击矿压电磁辐射预报指标。表3 列出了临界值和偏差值指标。通过利用以上指标，我们已经成功预测了多次冲击矿压，在多次冲击矿压中保护了我们自己。表 3冲击矿压预报指标最大幅值平均幅值脉冲临界点17310422偏差值35%15%150%3.5 电磁辐射预报的精确性假如，被监测到的冲击矿压的 C 级作为临界点，则预测冲击矿压的精确度为 100%。假如，冲击矿压的 D 级作为临界点，则预测冲击矿的精确度为 73%。4 结论（1）在煤岩体加载变形和破坏过程中会有电磁辐射信号放出。电磁辐射基本上随着载荷的增加而增大，随着加载及变形速率的增加而增大。（2）在加载煤样发生冲击破坏之前，电磁辐射幅值总低于一个特定值，而在冲击破坏时，电磁辐射幅值会突然增加，电磁辐射脉冲会随着加载及变形的增加而增大。（3）现场观测显示了电磁辐射脉冲最大值，平均值和电磁辐射脉冲数会随着冲击矿 压危险性的增加而增加。工作面不同地点的电磁辐射特征和预报指标预报了多次冲击矿压。（4）假如，被监测到的冲击矿压的C 级作为临界点，则预测冲击矿压的精确度为100%。假如，冲击矿压的 D 级作为临界点，则预测冲击矿的精确度为 73%。参考文献1 窦林名,何学秋 冲击矿压防治理论与技术 ，中国矿业大学出版社,20012 窦林名 . 电磁辐射和声发射在煤矿和冲击矿压上的应用博士生论文， 中国矿业大学,2001,33 窦林名,何学秋 煤岩体破坏时的电磁辐射清华大学学报， 2001 年 12 月 41 期4.窦林名，何学秋：冲击矿压防治理论与技术，中国矿业大学出版社，2001 5.方焕明：浅谈生产矿井冲击矿压及其防治，煤炭图书馆，20026. 王省身：矿井灾害防治理论与技术，中国矿业大学出版社，19897.蒋国安、吕家立：采矿工程英语，1998 8.全国自然科学名词审定委员会：煤炭科技名词,19969. 陈炎光、徐永祈：中国采煤方法，中国矿业大学出版社，199110. 冯昌荣：煤矿矿井采矿设计手册，煤炭工业出版社，198411.冯昌荣：采矿工程专业毕业设计指导，中国矿业大学出版社，1996
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