Numerical Simulation of the Effect of Joint Fissures on Mechanical Properties of Phosphorite
In the process of deep phosphate mining,rock burst and other geological disasters occur in underground stopes and roadways due to the occurrence and unstable expansion of cracks in phosphorus blocks,among which the inclination angle and width of cracks can change the stress state of phosphorus blocks and affect the rock burst tendency of phosphorus blocks.Taking the rock burst disaster in Wawu Ⅳ mine section of Yichang as the engineering background,the stress-strain curve,peak strength,crack propagation characteristics and rock acoustic emission curve with loading step under different crack inclination and width were analyzed by RFPA2D numerical simulation software,and the influence of different crack inclination and width on rock burst tendency and failure characteristics of phosphorus block were explored.The experimental results show that the peak strength and peak strain decrease gradually with the increase of crack angle,the effect of crack width on elastic modulus is very small,the peak stress decreases with the increase of crack width,and the peak stress level tends to be consistent with the increase of crack angle.With the increase of crack inclination angle,the failure mode of rock gradually changes from brittle failure to plastic failure.When the crack inclination angle is 0° and the crack width is 1.5 mm,the failure mode changes ab-ruptly,showing the inverted"V"crack growth characteristics.The crack growth characteristics are similar at different crack widths when the crack inclination angle is 30°,60° and 90°.Acoustic emission can well monitor the process of rock crack gen-eration and rock failure.The occurrence time and duration of acoustic emission can also be compared,and the tendency of rock burst is obviously weakened with the increase of crack inclination angle.
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