Abstract: The view that the overlying key strata come into being long-span inverted cantilever structure with coal mining face advancing is proposed by analyzing the datum from the observation of coal mining stress of No.12314 fully mechanized coal mining face in Huojitu pit of Daliuta Mine and researching the hydraulic powered support jammed mechanism and process of elementary mining in the No.12314 face for guiding the production of the face in a shallow buried seam with ultra closed distance to the above seam safely and effectively. The cantilever structure of overlying key strata break up and then happen to be instable due to sliding reversely as a result of the instability of boundary coal pillar near the open-off cut of the above seam since the working face go beyond the boundary goaf coal pillar of above seam. The hydraulic powered support jammed accident occurred due to the upper load transferring to the brackets in the working face at a short time. Some targeted treatment measures are proposed from the aspects of technology, design, locale management and etc, which provides technical support and gathers experience for the production of the face in a shallow buried seam with ultra closed distance to the above seam safely and effectively.

Key words: elementary mining, closed distance seam, working resistance, hydraulic powered support jammed, measures