Instability mechanism and control of hydraulic support in fully mechanized longwall mining with large dip

In terms of the characteristics of stability control of hydraulic support under the condition of the fully mech- anized working face with large seam dip angle,rotating,large mining height and false bow oblique,and combining with the geological and engineering conditions of fully mechanized working face numbered 12124 in Pan’er Mine,this pa- per studies the mechanism and method of stability control of broken roof and hydraulic support and scraper conveyor under soft coal conditions. Based on the analysis of field observation data,two instability modes including the dumping and falling of hydraulic support in fully mechanized working face with large dip angle are constructed to analyze the force characteristics of the supports by comparison. The relationships between the instability of the supports and seam dip angle,beam of support,the friction coefficient of the direct top are revealed. Then " threshold with pressure" of moving hydraulic support with pressure is derived,and the method of moving support with load,laying metal net,con- tacting roof and chasing coal winning machine are provided. The ratio of adjusting oblique in the rotating mining area is designed to be 1 ∶ 3 by comprehensive analysis,and the decline value of conveyor in bow pseudo-inclined mining area is determined to be less than 304 mm. With the measures of preventing sliding and falling of “ three machine” which are installed jack with preventing sliding and falling,and the effective control on the “three machine” stability, wall caving and roof falling,the safety and high efficient mining of thick coal seam with large seam dip angle are real- ized.