Research on Safe and Efficient Retraction of Hydraulic Support in Fully Mechanized Mining Face and Control of Top Plate Pressure

Using the multi-channel formed by the auxiliary transportation roadway to quickly retract the hydraulic support in the working face is a safe and efficient moving method. Taking the period when the 22303 fully mechanized top coal caving working face is connected to the main retraction channel as the research background, in-depth research was conducted on the reserved width of the isobaric coal pillar and the isobaric position when stopping mining through on-site monitoring, theoretical calculation analysis, mechanical mechanism analysis, and other methods. The results showed that the reduction of the mining speed of the working face can also reduce the step distance of the roof, which is conducive to the early rupture and compression of the roof; The width of the isobaric coal pillar determined by theoretical calculation is 6.1 m. When the mining speed of the working face decreases or even approaches 0 m/d, the step distance of the incoming pressure is 6.3 m. It is comprehensively judged that the isobaric measures for stopping mining will be implemented from the position of about 6.3 m near the main retreat channel of the working face; There are four types of mutual feedback relationships between isobaric coal pillars and their overlying rock layers, which provide clear basis for the safe and efficient implementation of hydraulic support retraction operations. Based on relevant production experience, a series of prevention and control methods and response measures have been proposed for the period of penetration and subsequent withdrawal operations.