NUMERICAL SIMULATION ON MINING EFFECTS OF UPPER COAL SEAM ON LOWER COAL SEAM OF SPLITTING AREA OF SPLITTING AND MERGING COAL SEAM**

The 7225 face is above the gob of 7118 face. The elevation of face ranges from –452.9 to –485.6 m, and ground elevation is +25.0 m. Strike length of the face varies from 417 to 527 m, 474 m, and the length of 121 m in width.72 coal seam in this face belongs to Lower Shihezi Formation of Lower Permian, thickness changes from 1.70 to 2.50 m, an average thickness of 2.50 m, occurrence is stable, spacing between 71 coal in the upper layers and 72 coal varies from 0.8 to 9.3 m, with an average 5.0 m, and the spacing of 82 coal in the lower part and 72 coal ranges from 14.35 m to 16.20 m, an average thickness of 15.15 m, coal seam dip angle vies from 8 to 16°, the average angle is 10°. 2. Establishment of model 2.1. Geometric model The actual geological conditions are simplified appropriately. The length of the model is 260 m, and the strike length is 300 m. The total height of the model is 116.86 m. The widt