Study On The Energy Evolution Characteristics Of Deep Coal-rock Gas Compound Dynamic Disaster

With the increase of coal mining depth in China,the frequency and intensity of coalrock gas compound dynamic disaster show an increasing trend,which seriously threatens the daily safety production of coal mines.Therefore,it is of great practical significance to study the mechanism of coal-rock gas compound dynamic disaster in deep mine for coal mine prevention and control.This paper adopts the method of theoretical analysis,experimental research and numerical simulation combined with the background of a coal mine in the eastern China,and successively carries out research on loading failure experiment of coalrock conbination,numerical simulation of failure process of coal-rock conbination containing gas and numerical simulation of gas dynamic disaster occurrence process of a coal mine in the east under stope environment.This paper focuses on the energy evolution characteristics of the breeding and occurrence process of coal-rock gas compound dynamic disaster in a coal mine in eastern China,and the following main research results are obtained:(1)Based on a gas dynamic disaster in a coal mine in eastern China,the occurrence process,main characteristics and causes of the accident are analyzed.It is concluded that there are two main reasons for the complex dynamic disaster phenomenon:(1)In deep high stress environment,the elastic potential energy accumulation capacity of coal rock is stronger than that of shallow deep coal rock;(2)The elastic energy accumulated in rock strata will transfer to coal seam when the disaster starts,which reduces the energy threshold of coal seam instability failure.(2)The coal and rock specimens obtained from coal and rock samples in a coal mine in eastern China under similar geological conditions of gas power disaster were processed.The basic mechanical parameters,impact tendency and outburst risk parameters of coal and rock were determined,and the loading failure experiments of coal and rock assemblages were carried out under different loading rates and coal-to-rock height ratios.The stress-strain variation law of rock mass,coal mass and coal mass during the instability failure of coal and rock mass is obtained,and the influence of different factors on the mechanical failure of coal and rock mass is analyzed.(3)The numerical simulation of the failure process of gas-bearing coal and rock assembly under different loading rates,coal-rock height ratio,gas pressure,dip angle and roof strength is carried out,and the elastic energy of rock mass to coal mass transfer during the instability failure process is monitored.The influence of different factors on energy zoning and elastic energy transfer of coal and rock mass is analyzed.It is found that among different influencing factors,the most sensitive factors affecting the ability of coal mass to accumulate elastic energy in the composite are gas pressure and dip Angle.When the gas pressure increases from 0MPa to 1.0MPa,the ability of coal mass to accumulate elastic energy in the composite decreases by 33.1%,and when the dip angle increases from 20° to40°,the ability of coal mass to accumulate elastic energy is enhanced by 7.78%.At the same time,different influencing factors(excluding dip angle)affecting the sensitivity degree of rock mass transfer elastic energy density are in the order of loading rate > gas pressure >height ratio > roof strength from strong to weak.(4)A three-dimensional numerical model of coal rock mechanics system under stope environment is constructed by using FLAC3 D numerical simulation software.The breeding and launching process of coal-rock gas compound dynamic disaster is simulated through dynamic excavation,and the evolution characteristics of elastic potential energy field of coal rock are analyzed.Based on this,the coupling mechanism of elastic energy "coal accumulation and rock mass transfer" is analyzed,and the energy criterion of coal-rock gas compound dynamic disaster is put forward,which has important guiding significance for the prevention and control of coal-rock gas compound dynamic disaster in deep mine.