472 / 2018-12-31 09:02:20

Study on the Microstructure Evolution of Coal and Its Influence on Mechanical Properties under Different Moisture Contents

coal, moisture content, uniaxial compression, mesostructure, fractal dimension

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Three kinds of typical Chinese coal types of Hongshaquan coal, Wucaiwan coal and Shenmu coal were selected. The uniaxial compression experiment was done for coal samples with different moisture contents (0%, 25%, 50%, 75%, 100%) by self-designed mechanical test and image acquisition bench to explore the influence of moisture content on the mechanical properties during crushing process. And combined with the coal surface image collected by high-speed camera, the fractal theory was used to analyze the mesostructure of coal surface during the crushing process. The results show that the higher the degree of coalification, the greater the compressive strength. The compressive strength and elastic modulus of Hongshaquan coal and Wucaiwan coal with low degree of coalification have positive relationship with moisture content, while the Shenmu coal with high degree of coalification shows the opposite law. The fragile interval of the Hongshaquan coal is between 0-25% of moisture content, the Wucaiwan coal is easily broken at about 25% moisture content, and the Shenmu coal is most vulnerable to breakage at the moisture content of 100%. And there is a nonlinear relationship between the surface mesostructure and its mechanical properties during coal crushing process.