Experiment Study On Effect Of Temperature On Permeability Of Coal Under Fluid-solid Coupling

This thesis takes the different regions’ sample of raw coal as studying objects, uses ourselves-developed fluid-structure interaction three-axis servo system seepage test units containing heat flow of gas, conducts experimental study on how temperature effects coal’s seepage under the condition of fluid-structure interaction, and adopts double porosities-permeability model to theoretically analyze the change mechanism of coal’s permeability rate. The results are as follows:① Through the coal sample tests about permeability rate under different temperature and different effective stress, we concluded: under the condition of more effective stress, the permeability rate of coal samples decreased gradually as the temperature increased; under the condition of less effective stress, the permeability rate of coal sample tend to rise first, then drop as the temperature increased.②With analysis of how slippage effect influences coal sample`s permeability rate under different temperature, and calculation of absolute permeability rate and slippage factors, we found coal sample`s absolute permeability rate showed the tendency of decrease as the temperature increased; By contrary, slippage factors showed the tendency of increase, that is to say, slippage effect is increasingly obvious.③Through the seepage tests of heating-cooling cycles of coal samples under different gas pressure, we get the coal samples` permeability rate decreased after heating-cooling cycles. And with the increase of several cycling times, the coal samples` permeability rate gradually dropped and tend to be stable.④Through the coal samples’ seepage tests under different bedding directions, we found with the same effective stress, the permeability rate and radial direction of parallel bedding coal sample was bigger than one of vertical bedding coal sample, but volumetric strain and axial strain of the former should be less than the latter ones.⑤Based on double porosities-permeability model, we drawn the conclusion that the coal sample`s permeability rate is influenced both by "porosity" of matrix and "fracture" between matrixes. By analyzing the temperature rise caused by thermal expansion effects on double porosities-permeability model, we concluded "fracture rate" between matrixes decreased. Thus, coal’s permeability rate decreased.