| Aiming at the problem of strong strata bebaviors occurring during face mining out of the upper dip concentrated coal pillar of a room mining goaf in Shendong mining area, based on the field observations, theoretical analysis, numerical analysis, the authors studied the mechanism and prevention technology of strong strata behaviors.Seven models in view of the structures of stratas between the two seams were proposed for the first time, including four types of all stratas between the two seams broke and three types of not all stratas between the two seams broke, then the seven models were divided into three simple structures including "All stratas breaking" structure, "Not all stratas breaking" structure and "Combinated" structure, then the method that discriminating the damage of the structural of stratas between the two seams under impact action was obtained through analyzing the stability of these three simple structures under impact action; the effects that the roof’s breaking has on the abutment pressure applied to coal pillars was analyzed, and the formula that discriminating the stability of the small coal pillars was obtained; "Single rotary rock block" formed by the main roof was proposed for the first time, and the support load after the all of the structures between the two seams were destroyed was analyzed, then the strong strata bebaviors was explained reasonably.Based on the achievements above, the prevention measures of prompting the room mning goaf and blasting the concentrated coal pillar were proposed. To the measure of blasting the concentrated coal pillar, the formula calculating the safety distance was obtained, and that the face should be mined after the overburden of the pillars out of stability was compacted was proposed. Based on the optimal selection, the measure of the blasting the concentrated coal pillar downhole was applied in Shigetai Coal Mine of SHENHUA SHENDONG COAL CORPORATION LIMITED and the measure turned out a notable field application effect. |
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