Application of directional long borehole subsection hydraulic fracturing technology in Buertai Coal Mine

In order to solve the problem of strong ground pressure behavior of fully mechanized top-coal caving face under the influence of hard roof and concentrated coal pillar, the design principle of directional long borehole subsection hydraulic fracturing is analyzed, and the fracturing design scheme considering the influence of “square” of the working face is proposed, which is applied in 42202 fully mechanized top-coal caving face of Shendong Buertai Coal Mine. The results show that after the directional long borehole staged hydraulic fracturing technology is implemented in the “square” range of the working face, the incoming pressure intensity and incoming pressure step distance in the fracturing area of 42202 working face decrease significantly, and the incoming pressure step distance decreases by 4.3%. When the pressure is applied, the average resistance of the support is reduced by 6.9%, the dynamic load coefficient is reduced by 4.2%, the coal wall of the working face is basically free of obvious caving, and the collapse of the goaf at the tail of the machine is sufficient. The approach of two sides of the auxiliary transportation chute in 42202 working face is reduced by 30.0%, and the approach of the top and bottom plate is reduced by 24.2%; the maximum stress of the auxiliary side is reduced by 32.1%, and the stability of the surrounding rock along the auxiliary transportationchannel is improved as a whole. After fracturing, the stress of anchor cable is greatly reduced and the stress of anchor bolt fluctuates violently. It is proved that the directional long borehole staged fracturing technology can effectively solve the far-field overburden structure of the working face, make the overlying basic roof collapse orderly and form a stable “voussoir beam structure”, and ensure the “gangue of gob-hydraulic support-coal wall of the working face” stability. The results can provide experience and basis for rock stratum control under similar mining conditions.