Theoretical model of drawing body in LTCC mining

This paper theoretically describes the shape of drawing body in LTCC and its influencing factors. The Berg- mark-Roos granular mechanical model ( B-R model) was adopted with the consideration on the influence of shield beam on drawing process and drawing body. The B-R model was modified by introducing the correction coefficient of gravity acceleration (K) and K was obtained through the experimental simulation and PFC3D numerical simulation. The modified model can precisely describe the drawing process and the theoretical shape of drawing body can be calculated by using this model. The difference value of the friction coefficients between the support shield beam and granular top- coal can lead to the different values of maximum migration angle θG ,and the different θG is the basic reason for the drawing body’s characteristic of developing toward the front of the support. This conclusion conforms to the shape of cut-variation ellipsoid proposed in BBR system. This model can accurately predict the drawing time in different heights of coal seams.