Research on weakening thick and hard roof by ground deep hole hydraulic blasting technique
To prevent accidents caused by the strong shock waves resulting from large-scale roof caving during the first pressure in conditions of shallow burial depth,thick and hard roof,and ultra-thick coal seam mining,this paper proposed a ground deep hole hydraulic pre-fracture blasting technique to weaken the thick and hard roof.By using theoretical analysis and numerical simulation methods,the feasibility of hydraulic blasting was verified and the reasonable interval of holes was determined.Industrial tests in the 4302 comprehensive workface of Kouqian Coal Industry were then successfully conducted.Numerical simulation results showed that for the same charge,the maximum equivalent force of the borehole wall was 1.45 times higher and the explosive fissure zone was expanded by 38%when water-coupled charge blasting was used in comparison with air-uncoupled charge blasting.In the case of a borehole diameter of 180 mm and a charge diameter of 120 mm,hydraulic blasting could create a rock fissure zone with a diameter reaching 11.06 m.The field experiment effectively resolved the technical challenges related to charging and stemming,achieved an earlier occurrence of first pressure on the working face,and realized the normal periodic fracturing of the overlying rock with the continuous advancing of the working face,which confirmed the viability of the ground deep hole hydraulic blasting.
thick and hard roofinterval of holesnumerical simulationhydraulic blastingfirst pressure
万方数据
维普
