Dynamic pressure mechanism and pre-control technology of gob-side roadways for large mining height working faces
Wall rock deformation control of gob-side roadway is a technical difficulty of roadway control.The greater the mining thickness of coal seam and strength of overlying rock are,the more difficult the gob-side entry deformation control is.Aiming at solving the problem of dynamic pressure control of gob-side roadway for large mining height working face at Yushupo Coal Mine,the mechanical model of lateral hanging plate structure for gob-side roadways was established.The theoretical analysis shows that the maximum lateral hanging length of main roof is 4.69 m,and the maximum strain energy density of main roof is located at 5.51 m in coal pillars,which is 2.831×106 J/m3,and the accumulated strain energy of main roof is 3.269×107 J.By means of numerical simulation,the development of plastic zone,deformation law and stress distribution characteristics of surrounding rocks in gob-side roadway were further analyzed.It was found that the supporting stress of goaf coal pillars can reach more than 35 MPa,which is the main factor for increasing stress on bolt and cable in roadway coal pillars and the deformation and failure of coal pillars.The comprehensive in-site technical methods of"pressure relief hole+lateral roof cutting"were used to control the dynamic pressure gob-side roadways.The design diameter of the pressure relief hole is 108 mm and the depth is 7 m.The hydraulic fracturing holes are L hole and S hole,the aperture is 60mm,the spacing is 8 m,the vertical fracturing height is 50 m and 30 m,respectively,and the water injection rate is 80 L/min.According to the in-site practice,the deformation of wall rocks of roadways was reduced by more than 30%compared to the section without pressure relief,and the floor heave of roadways was obviously controlled.
large mining heightgob-side roadwaylateral hanging platepressure relief holehydraulic fracturing
万方数据
维普
