Abstract: The rational layout of mining roadways below upper synchronously mining longwall faces under the condition of ultra-close coal seams is the key issue for the safe operation in Huojitu coal mine. To overcome this critical challenge, this paper studied the double-roadway layout under the upper section coal pillar in less than 2 m interval coal seams through numerical simulation and field measurement．It is showed that when the widths of section coal pillars are 20 m and 35 m, the maximum cover depths of lower double-roadway are 100 m and 150 m, respectively. By placing the double-roadway under the upper 35 m-wide section coal pillar in No.3 panel of Huojitu mine, the deformation of the roadway is only 50 mm totally in spite of 3 times mining influence. The roadways can be in safe and normal use without maintenance. This provides reference for safe and efficient mining under the similar shallow ultra-close coal seams condition.

Key words: ultra-close coal seams, section coal pillar, double-roadway layout, shallow coal seam