Application of forced caving of hard roof by axial fracture cutting and fracturing of abrasive jet

LI Hongping; DU Taotao; SUN Bingcheng; YANG Wei; CHANG Bo; ZHAO Zhipeng; JIA Bingbing; LIU Jiang

doi:10.11799/ce202312018

Abstract：In order to adopt the new technology of abrasive jet axial clipping to complete the initial roof caving of the hard roof with expanded surface,the industrial field test was carried out in Kuangou Coal Mine to determine the key technical parameters of abrasive jet slotting and fracturing,and the initial roof caving project of abrasive jet axial clipping was designed and carried out.The implementation process was monitored by means of hydrometer,drilling peeping and on-site observation of water outlet.The effect of mining process is tested by microseismic monitoring,support pressure monitoring,coal body stress monitoring and roof caving observation.The results show that,by controlling the main technical parameters such as pressure,time and sand amount,the industrial test of fracture radius of 200mm and length of 300 mm has been completed,and the fracture radius of 5 m and 10 m has been completed.The results of the initial implementation of surface expansion verify the roof joint network of the whole surface expansion,which indicates the effectiveness and reliability of the implementation process of the technology.The test and analysis of the effect of stoping process after surface expansion show that the caving situation of the first roof caving with the axial cutting of the frosted jet basically achieves the effect of the traditional blasting at the same time,the effect of the roof on the coal wall of the working face is significantly improved,the stress drop of 2.9 MPa occurs in the coal body during the engineering implementation process,and the stress concentration degree of the coal body is significantly improved during the surface expansion stoping.The stress of coal body does not form stress concentration,which plays a good pressure relief effect.