To explore a new method of hard roof treatment in coal mine,the axial cutting technology of hard roof with abrasive jet is introduced,and the key technical parameters of slit cutting and fracturing are determined by carrying out industrial tests,and the anti-impact engineering practice is carried out. Its performance is evaluated by means of water pressure meter,borehole observation and observation hole outflow observation,microseismic monitoring,support pressure monitoring and stress monitoring in coal seam. The results show that the reasonable slit cutting parameters are as follows:slit depth 200 m,slit length 300 m,slit pressure 40-50 MPa;The fracturing parameters are as follows:fracturing pressure 50-55 MPa,fracturing time 20-30 min;After slit cutting and fracturing,it effectively promotes the generation and propogation of cracks in roof strata,and undermines the integrity of the roof. The fracturing radius is 10-20 m. Compared with the traditional roof cutting technology of top blasting,the microseismic event concentration area is transferred from 80 m to 130 m in advance of working face,and the microseismic energy release is mainly small energy events after the combined treatment of abrasive jet axial top-cutting and blasting. The pressure step of the period is obviously reduced,the influence range of mining stress and stress concentration coefficient are obviously reduced,the activity strength and dynamic load effect of surrounding rock are obviously weakened,achieving good bursting preventation effect.
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