Fig. 6

(a) Development characteristics of plastic zone in the mining floor of No. 3–5 coal seams. (b) The plastic zone range of the 50 m floor of coal No. 3–5 is pushed forward, (c) The plastic zone range of the 70 m floor of coal No. 3–5 is pushed forward, (d) The plastic zone range of the 200 m floor of coal No. 3–5 is pushed forward.