1、英文原文DOU LIN MINGCHINA UNIVERSITY OF MINING AND TECHNOLOGY,CHINAXU FANGJUN,ZHANG XIUFENGHUAFENG MINE,SHAN DONG, CHINAEME rock burst monitoring in coal mine huafengAbstract :the electromagnetic emission is caused by the inhomogeneous variable speed and the deformation of various parts of the coal and
2、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 w
3、hich 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
4、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
5、 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 ex
6、pands, there are a great number of charges or electrons on it. The electrons escape, during the crack expansion at variable speed, EME and EAE are radiated at the same time. After the crack expansion, parts of the coal around the crack contract, meantime the Coulombs field is formed because of the h
7、igh 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 distributi
8、on and EME amplitude distribution of HuaFeng coal sample, which has high danger of Rock Burst.a) 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 sampleFig.1 the r
9、esult of coal sample experimentFrom 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 defor
10、mation 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
11、 out on the basis of EME experiment. The warning EME value of Rock Burst of the 4# coal seam in HuaFeng Mine are listed as Tab 1 shows:Tab 1. The warning EME value of Rock BurstCoal seamThe stress value of brittle failure/MpaThe EME value of coal failureMaximumWarning valueAmplitude/mvImpulseMaximum
12、Warning valuemaximumWarning value4#16.112.9433346610488The 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 Th
13、e 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, cau
14、sing 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
15、. 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 l
16、ow-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 Bu
