Abstract: In order to analyze the mining pressure behavior mechanism of lower coal seam working faces in shallow and closed coal seams while mining through upper coal seam goaf and left coal pillars, and determine the support resistance reasonably, the mine pressure change law and the support resistance of the lower coal seam in shallow and closed coal seams have been discussed. Results show that with the increase of coal seam spacing support resistance decreases. The mining pressure behavior will be influenced greatly by coal seam spacing when the coal seam spacing is less than 15 m while the influence will be very limited when the coal seam spacing is more than 15 m. The mining pressure behavior are different under the goaf, the left coal pillars and the coal seam：under the goaf the roof breakage pace is 9.8 m, the maximum operation resistance is 10 920 kN and the dynamic factor is 1.3; under the left coal pillars the roof breakage pace is 10.8 m, the maximum operation resistance is 11 065 kN and the dynamic factor is 1.35; under the coal seam the roof breakage pace is 12.2 m, the maximum operation resistance is 10 742 kN and the dynamic factor is 1.39.

Key words: ultra closed coal seams, mine pressure law, numerical simulation