Study On Damage Rule And Test Method Of Gas-Rich Coal-Petrography Under Engineering Disturbance

The dissertation focuses on the important basic theory of gas prevention and control in deep mining of gas-rich and low-permeability coal seam--study on the system problem of damage and failure evolution,gas migration and test methods about gas-rich coal strata under engineering disturbance.Damage and rupture evolution mechanism of the gas-bearing coal-series strata due to excavation,explosion and mining disturbances,and gas seepage and gas effusion law are theoretical analyzed;basic law of gas containing in coal seams and strata in deep mine and damage and rupture evolution mechanism of the gas-bearing coal-series strata under the external disturbance are experimentally studied.Conducting experiments to study the basic rules of the occurrence of gas in coal seams and rock strata in deep mines;theoretically analyzing the evolution mechanism of damaging gas-rich coal seams and rock strata through driving,dynamite and exploitation,as well as the rules of gas seePage and gas emission;using the numerical values of the geographical conditions in coal seams in the experimented mines to conduct a simulation study of the evolution of damage to the experimented coal seam under external disturbance in the coal field of Qinshui and of the rules of gas migration;through the development of an explosion-proof ultra-precise quantitative detection system of trace gas and the establishment of a process and technical system of field measurements,industrial tests of field measurements are developed underground in the experimented coal seam of the coal field in Qinshui.The results of the experiments are as follows:(1)The damage mechanism and gas percolation rule of gas-rich coal strata under engineering disturbance are theoretically analyzed,the distribution characteristics of three belts in horizontal direction of disturbed coal seam,as well as the three belts division and gas percolation rule after stress reconstruction are obtained.Through the analysis,the propagation rules of energy and stress after blasting shock wave and stress wave acting on coal wall of blasting borehole in disturbed coal seam,and the initiation conditions of secondary expansion of coal body crack around blasting borehole under the action of blasting gas are obtained.Through the analysis,the distribution characteristics of the three vertical and horizontal zones formed by mining disturbed overlying strata and the gas migration law in the fracture field can be obtained.(2)Systematically expounding on the rules of gas emission in the gas-rich coal.seams and rock strata under engineering disturbance,a mathematical model of gas emission of driving-disturbed coal seams based on the occurrence Parameters of coal seams and the driving production Parameters are acquired;The sources of gas during the damage and destruction process of disturbed overburden strata are obtained,According to different gas sources,the law of gas emission from rock,adjacent coal seam,coal wall,coal falling and goaf could be obtained,and the corresponding measurement method and gas emission mathematical model are established.(3)Taking QinShui coalfield which has the gas-rich coal strata as the experimental object,through the experimental study on the characteristics of microscopic pore development,the law of permeability,limit adsorption capacity and fracture distribution along with lithology can be obtained.(4)Damage and rupture evolution mechanism of the gas-bearing coal-series strata under the engineering disturbance is experimentally studied.The gas emission characteristics at different time and position of the driving disturbed gas-rich coal seam are obtained by using the method of source test,so that the time-space law of damage evolution of disturbed coal seam by tunneling is analyzed from a macroscopic perspective.Using the statistical method of gas extraction Parameters,the limit value of damage and destruction of disturbed coal seam caused by blasting in experimental working face is studied.The micro-seismic monitoring method is used to obtain that the experiment working face mining coal rock damage scope of longitudinal slot and the lateral horizontal scope.(5)Studying on the damage evolution rule of rich in gas coal-petrography under the engineering disturbances through the application of the numerical simulation method,combined with the mine geological conditions of QinShui coal field experiment,the numerical calculation model is established,the limits of effective gas drainage time and the width of damage and failure zone in the tunneling disturbance process of experimental coal seam are obtained by using COMSOL numerical simulation software.Through the PFC2D numerical simulation,it can be calculated the radius of the fractured area in the coal seams around the boreholes disturbed by blasting and the damaged area.with the aid of the UDEC numerical simulation,it is concluded the damage scope of overlying strata with the advance of the working surface.(6)Based on the quantitative analysis system of explosion-proof ultra-high precision tracer gas,an actual measurement technology system based on the principle of gas tracer is established for the first time,and the measured results in the experimental mine show that the measured values of the damage zone range of disturbed coal seam by tunneling and blasting are consistent with the theoretical calculation results,the error value between the measured value and the theoretical calculation result is in acceptable range.