外文翻译-矿井煤岩动力灾害电磁辐射预警技术.pdf

1、 翻译部分翻译部分 外文原文外文原文 Electromagnetic emission graded warning model and its applications against coal rock dynamic collapses（Enyuan Wang,Xueqiu He,Jianping Wei,Baisheng Nie,Dazhao Song）Keywords:Electromagnetic emission Damage mechanics Electromechanical coupling model Numerical simulation Graded warnin

2、g abstract：Dynamic collapses of deeply mined coal rocks are severe threats to miners.In order to predict the collapses more accurately using electromagnetic emission(EME),we established a loaded coal rock EME electromechanical coupling model based on statistical damage mechanics.By using it,we numer

3、ically simulated both the accumulative pulse and strain ratios.We further improved the model with the Weibull pattern parameter,which has important effects on simulated results and can be applied to judge coals homogeneity,and determined the pattern parameter and its value domain.Based on the revise

4、d model and the characteristics of coal rock deformation and fracture,we setup EME graded warning criteria against coal rock dynamic collapses by determining static critical coefficient and dynamic trend coefficient.We have applied this model to predict and deal with coal and gas outburst and rock b

5、urst occurring at Xie I and Taoshan Mines,respectively.All these verifications show that the model has many advantages and provides more sensitive and accurate warning for dynamic collapses.1 Introduction Electromagnetic emission(EME)always occurs along with coal rock deformation and fracture.It is

6、closely related to the load on coal rock and to the degree of coal rock deformations and fractures under load.In nature,the deformation and fracture of coal rock mass are the results of formation,expansion,combina-tion,integration of some micro-defects or micro-cracks,and the internal damages of coa

7、l rock under stress 18.EME is related to the features of coal rock material,such as the damage parameters and the constitutive relation,and directly associated with the evolution and propagation of the internal defects 2,912.In the late 1980s,Kyoya et al.13 and Kyoya 14 first applied damage mechanic

8、s to analyze the rock mass stability of under-ground chambers.Kawamoto 15 introduced the anisotropic damage theory of second-order symmetric tensors to his studies on non-continuous rock mechanics and predicted the variables of rock mass damage with the finite element method.Zhang and Valliapan 16,b

9、ased on Kawamotos theory,put forward that the rock fissures length,direction,and density comply with certain probability distribution,and analyzed the random anisotropic damage mechanics of rock mass.Swoboda and Yang 17 com-bined the endochronic theory with the free energy function and obtained the

10、damage evolution equation and constitutive rela-tionship between the jointed and fractured rock masses.With the EME technology being broadly applied in coal mining,scholars from various countries have connected the damage of coal rock with EME and studied their inherent relationship.As Frid 18 state

11、d,the so-called EME is actually EM waves generated and emitted toward surrounding media by energy release due to microdamage.So EME is inevitably related to coal rock damages;in other words,EME activities indicate the degree of microinjury to which coal rock is subjected.He et al.2,Wang 3,and Wang a

12、nd He 19 believed that EME of loaded coal rock mass is an outward emission phenomenon of EM waves caused by the microcracking in the process of deformation and fracture,while the microcracking is the result of internal microinjury,i.e.,EME is connected with the damage process.According to coal rock

13、strength statistics and damage mechanics,Nie et al.20 estab-lished his electromechanical coupled model(EMCM),according to which the destruction of coal rock materials results from the accumulation of micro-elements of internal micro-damages and EME can reflect the damage degree of coal rock mass.In

14、addition,scholars from China and other countries carried out extensive researches on EME effects and mechanisms due to coal rock damage.Based on fracture mechanics and electrodynamics,they established some micromathematical and physics models of coal rock EME and applied them for preliminary theoret

15、ical ana-lyses 7,8,2124.However,most of these models were micro-scopic and difficult to meet the requirements of practical applications and especially challenged by the determination of warning critical value and hazard level,etc.This article tries to solve the above problem.We first describe the fo

16、ur stages of coal rock fracture and characteristics of EME(Section 2),then put forth an EMCM of coal rock EME based on statistical damage mechanics,further improve it and determine its related important parameter,the pattern parameter,by numerical simulations(Section 3).We further set up EME graded warning criteria of coal rock dynamic collapses relevant to EME pulses and intensity,determine dynamic trend coefficients for forecasting,and present the warning methods and countermea-sures(Section 4