| The coal seam infusion has an important significance in coal mine safety and production, especially plays an important role in the gas control, dust prevention, rock burst prevention. So after coal infusion coal body structure (such as porosity, permeability changes and distribution of research content) is necessary, and another important phenomenon of water flooding after water infusion in coal body is followed the increase of moisture content, it not only has important influence on the coal body structure, but also can control the gas and dust, so the above several aspects of the study is very important to carry out water, after the research on the change rules of coal body structure and the moisture range has important significance.Using comso14.3b 2D numerical simulation, through the analysis and Research on related theory combined with the related basic parameters obtained from field test, model is set up to simulate the two-dimensional numerical water infusion in coal body, by means of numerical simulation combined with post processing pressure of injection pressure, injection time of 0-6 d, 4-14 MPa after injection of coal around the borehole water pressure distribution, displacement distribution, porosity distribution, water distribution and its variation are calculated, through a series of study reached the following conclusions:(1) After water infusion around the borehole pressure and porosity and permeability shows a circular distribution, water distribution has an elliptical contour distribution; pressure, porosity and permeability and moisture distribution and displacement accord with Gauss2D distribution.(2) Around the coal borehole in the process of water infusion pressure, porosity and water with increasing injection time and injection pressure is gradually increasing and expanding rapidly to the more distant; moisture distribution is obviously anisotropic in the longitudinal and transverse, its distribution in the horizontal and vertical scale is 1.64174.(3)Center of pressure distribution contour,porosity distribution contour and water distribution contours remain centered drilling.Around the coal borehole porosity with prolonged injection time, when the moisture content increased to a certain extent coal porosity started to grow, with the increase of moisture content, porosity increased gradually, the inflection point coal porosity increase rate accelerated when coal water reaches a certain value, moisture inflection point and borehole distance more far increased the porosity lower inflection point, the lowest water content rate of 2.5%, water injection after coal injection between the porosity and the water pressure is linear relationship, the injection pressure is greater, the linear intercept of the smaller, the greater slope.(4) High pressure exists a critical rapid breakthroughs in injection process value, when the injection pressure is greater than the pressure of water injection effect to be more obvious, in view of the scope of this study for the breakthrough pressure of water injection pressure 10 MPa.(5) According to the numerical simulation of water injection and processing data, through stepwise regression, exponential regression, polynomial regression, linear regression method to establish the water after drilling around the coal water pressure distribution, porosity distribution, water distribution on water injection pressure and time at different positions of the distribution function.The above research results indicate that, on the basis of the theory and the physical equations suitable, build simulation model of research on coal seam water injection can not only greatly lower the workload of numerical coupling of multi physics field, and is favorable for carrying out multi factor comprehensive research, research on water flooding issues more fully, is conducive to a more comprehensive understanding of the effect of coal seam water injection. Engineering design and Study on the guidance of coal body water can achieve the expected result has guiding significance. |
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