Effect of Face Length in Initial Mining Stage of Fully Mechanized Top-Coal Caving Face with Large Mining Height

Based on the field measurement of the end resistance of the support during the initial weighting of the basic roof and the macroscopic mine pressure behavior during the weighting period of 101, 22,211, 103 and 301 fully mechanized caving face in Changchun Xing Coal Mine, the mine pressure law of the working face is summarized and compared. Furthermore, the relationship between the working face length, the working resistance of the support (the weighting strength) and the macroscopic mine pressure behavior is obtained. In the range of face length 126–230 m, with the increase of face length, the end-of-cycle resistance of the support gradually increases, the dynamic load coefficient of the support gradually increases, and the strata behavior of the working face changes from strong to very strong. When the face length is short (126–140.5 m), the hanging roof area is too large to cause hurricanes when the working face is pressed, which threatens and damages the personal safety and equipment of the working face staff. Based on the above research, the problem of optimizing the surface length is proposed, and the surface length is determined to be within the range of 140–230 m.