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Study on Evolution of Mining-induced Fractures Field and Its Coupling Effect with Gas Seepage under the Conditions of High-strength Underground Mining

Author: PengYongWei
Tutor: YaoJianGuo;LiFengMing;QiQingXin
School: CCRI
Course: Mining engineering
Keywords: High-intensity mining Mined crack field Elastic -brittle-plastic Permeability stress sensitivity Gas Seepage Numerical Simulation
CLC: TD712
Type: PhD thesis
Year: 2008
Downloads: 884
Quote: 6
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China is one of the world's coal and gas outburst of the most serious. The common feature of recent years, the gas-related accidents occurred accident face most of the coal seam conditions for thick and extra-thick coal seam, most of the mining method used for mechanized mining caving coal, large mining highly mechanized mining of high-intensity mining method. However, the formation mechanism of the gas disaster, as well as coal and gas outburst, early warning of gas accident prevention, emergency rescue, basic research is not enough. Related research on the indirect cause of the gas explosion gas explosion hazard, such as how to flow with the gush is not deep enough, the coal mining fissures research concerns the impact of gas flow is not enough. In view of this, the paper with high intensity exploitation of mining coal for the study, the combination of field measurement and laboratory experiments, theoretical analysis of the combination of numerical analysis methods, the use of mining engineering, rock mechanics, fluid flow mechanics, multidisciplinary crossover method to study the evolution of the crack field of coal mining and gas flow field coupling. Papers papers structure diagram, thesis research content and results: (1) in order to obtain the internal and surface coal mining fissures, drilling peep line measurement method and the measurement window combined coal mined crack field measurement study of the field; based on the analysis of the coal mining stress distribution characteristics, proposed the concept of work ahead of coal mining crack field in its partition, and partition distribution characteristics and influencing factors were analyzed. (2) In order to simulate the coal fracture and its evolution, the non-uniformity of the coal through the appropriate mathematical methods to characterize. Specific approach is the use of Monte Carlo method to generate pseudo-random numbers, random assignment to the unit; comes Mohr-Coulomb model has been modified and is more suitable for coal-based bomb, developed with VS2005 FLAC 3D brittle-plastic constitutive model Fracture.dll. Live coal mining fracture observations as the initial state, FLAC 3D call Fracture.dll the coal mining fracture evolution simulation. (3) a series of coal permeability stress sensitivity experiments to simulate the mining of high-intensity gas seepage. Stress sensitivity of experiments, including single / three-axis penetration stress sensitivity experiments of the permeability of coal samples at different scales, the permeability of coal samples under different pore pressure stress sensitivity experiments, the permeability of coal samples stress sensitivity in parallel experiments. The main conclusions: (1) permeability of coal samples and the applied stress relationship satisfies the mathematical expression of the negative exponential relationship; different loading patterns, and varying degrees of permeability, large confining pressure on permeability than the axial compression; ② With The significant coal body size increases, the absolute permeability of coal samples with confining pressure stress sensitivity curve slope gradually smaller. When the coal sample size increases to d = 100 cm, the lower confining pressure affect the permeability of the coal sample is no longer obvious; case of the same size, the higher initial permeability of coal seepage paths larger , more easily compressed. ③ For low permeability coal, coal gas flow in the body exists in the lower pore pressure and flow rate of slippage effect. Lower pore pressure, relatively high permeability of coal, with sandstone oil and gas reservoirs similar characteristics. ④ With coal by force status changes, different coal seams ability to penetrate the change, the contribution of the main flow direction and flow rate will be changed; (4) on the basis of the above study, the analysis of the evolution mined crack field changes in coal permeability, seepage - stress coupled equations. Gas flow process analysis through numerical simulation study of the different options. (5) to heaven Wangpo Coal Limited 3207 Face of gas drainage for the background, use of research results, combined with COMSOL Multiphysics software for the numerical simulation of mined crack field effects on gas drainage. The study shows that the fissure orientation and direction of the gas flow field distribution plays a major role.

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CLC: > Industrial Technology > Mining Engineering > Mine safety and labor protection > Mine atmosphere > Mine Gas
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