3-D numerical simulation on the top-coal movement law under caving mining technique.

In fully mechanized top-coal caving mining, the top-coal is broken into loose state under stratum pressure, whose mechanical characteristics are different from the complete rock. Based on the three-dimensional Particle Flow Code (PFC3D), established the top-coal caving 3-D numerical simulation model, which can truly reflected the top-coal caving process, and carried out with different caving ratios and drawing interval simulations. During the initial caving process, top-coal particles will form a stable velocity field and the second loose region; the draw body is a deflect quasi-ellipsoid constrained by support shield, the deflect angle of axis decreases exponentially with the increasing of drawing time, the height of draw body decreases with increase in drawing time which presents the power function relationship; draw body cuts coal and gangue interface and forms a three-dimensional hopper surface, of which the central axis deflects towards the gob; under different cutting-caving ratios and drawing intervals, the top-coal extraction ratio shows a typical progressive stabilization effect with the face forward distance. [ABSTRACT FROM AUTHOR]