Design and field response analysis of double-sided staged hydraulic fracturing in gob-side entry under multi-layer hard roof condition

Abstract Aiming at the problem of deformation and fracturing treatment location determination of gob-side entry under the condition of multi-layer hard rock roof, based on the engineering data of I030902 working face in Limin Coal Mine, the combined beam load screening and numerical simulation were used to determine the fracturing horizon and its lateral loading position, and the staged hydraulic fracturing scheme of bilateral long and short holes was analyzed. Combined with surrounding rock deformation, support load, hole wall peep and microseismic records, the field response and effect were evaluated. The results show that Y2, Y8 and Y13 can be used as the design focus layers. The stress concentration positions of Y2 and Y8 are close to the gob-side entry, and the peak value of Y13 is biased to the old goaf side. The approximate maximum deformation of the roof and floor direction, coal pillar side and solid coal side of the unfractured section and the fractured section is about 225 mm, 180 mm, 125 mm and about 22 mm, 18 mm, 12 mm, respectively. The average working resistance of the two sections of the support is 9725 kN and 8943 kN respectively, and the fracturing section is about 8% lower ; the microseismic records of the fracturing section are dominated by 10 1 ~ 10 2 J events, and no events of 10 4 J and above are shown. The field response is generally consistent with the design goals of reducing deformation and reducing load, but the information of mining stage, monitoring window and supporting conditions is incomplete, and the existing data cannot separate the independent contribution of fracturing.