Study on hydraulic fracturing technology in initial caving of fully-mechanized coal mining face

The roof of fully-mechanized coal mining face in Ningtiaota coal mine is stable and difficult to cave. The impending roof with a large area has become a potential accident. In this paper, hydraulic fracturing technology was applied in the open-off cut of fully-mechanized working face in Ningtiaota coal mine to cut the roof. The fracture propagation process, pressure variation and roof caving state were monitored to llustrate the effect of this technology. This results showed that hydraulic fr acturing could effectively weaken the roof strata and ensured roof caving safety during initial mining period. The fracturing parameters, such as interval, depth, angle an d required fracturing pressure of boreholes, for working face were determined based on the roof conditions of this coal mine.This program was able to guarantee a sequ ential caving process, reduced mine earthquakes and ensured production safety during initial mining period.