Abstract:
In view of the occurrence of rock shock and other disasters during the working face excavation in Dongtan mine, the stress instability of the roof of the coal seam is easy to occur, with 63
上03 working face roadways and overburden as construction area, through the key stratum lithology analysis, judgment and actual comprehensive comparison, determine the key construction of roof strata directional drilling, and hydraulic fracturing, long for the thick sandstone roof in comprehensive coal directional drilling section hydraulic fracturing rock burst prevention and control to provide technical support.The results show that the middle sand strata in the upper part of the Permian Shanxi formation and the fine sand strata in the lower part of the Jurassic Santai formation are selected as the key strata for drilling.The construction of 4 roof directional long drilling has been completed, forming the roof continuous sliding drilling technology, with a single hole depth of 519-800 m and a total length of 2 517 m.The segmental fracturing technology of double sealing and single block backward fracturing of coal seam roof of Dongtan mine is formed through the segmental fracturing of four boreholes.There are 25 sections of segmental fracturing, with a total water injection volume of 1 286 m
3 and a construction pressure of 17.1-32.8 MPa.The pressure curve clearly reflected the fracture point, and the maximum pressure drop exceeded 10 MPa.At the same time, hydraulic fracturing greatly reduces the occurrence frequency of seismic events greater than magnitude 2 and magnitude 1-2 microseismic events.Meanwhile, the average value of the final resistance of the working face bracket after fracturing is reduced by 1.2 MPa, and the periodic pressure step distance is reduced by 7.3 m, which has achieved the effect of mine earthquake control.