Numerical analysis of influencing factors of steeply inclined coal face damage and instability.

In the process of longwall mining along the strike with steeply inclined coal seam, the coal face instability spalling seriously affects its safe and efficient mining. In order to explore the response law of damage and instability of coal face to its influencing factors, 3DEC numerical simulation was used to analyze the displacement characteristics and instability of coal face under different mining heights, inclination angles, coal cohesion and coal joint spacing in steeply inclined coal seam. The relationship between the above factors and the displacement of coal face is further obtained by multivariate nonlinear fitting, and the prediction model of coal face displacement is constructed. The results show that with the increase of coal seam mining height, the decrease of coal seam joint spacing and the decrease of coal cohesion, the horizontal and vertical displacement values of working face increase. With the increase of inclination angle of coal seam, the displacement value of working face decreases in a certain range, but the overall trend is increasing. The displacement (y) prediction model of working face based on coal seam mining height (x₁), inclination angle (x₂), cohesion (x₃) and joint spacing (x₄) is further obtained. The fitting degree R² of the fitting value and the actual value of the horizontal displacement and vertical displacement prediction model are 0.9692 and 0.9979, respectively. In addition, according to the actual engineering situation of a mine, the model prediction and 3DEC numerical simulation are carried out. The obtained displacement results of the working face are basically consistent with the actual monitoring results, which further verifies the reliability and scientificity of the displacement prediction model of the working face. [ABSTRACT FROM AUTHOR]