Double-spiral Cutting Parameters Optimization

The parallel cut is an effective way for driftage of the small and medium-sized sectionroadway to achieve rapid excavation with high efficiency and low consumption. Based on thesingle spiral cut method, double-spiral cut method is adopted and it is advantaged in cavitymaking and cutting success rate. Researches on double-spiral cut at present have been mostlyconcentrated on engineering applications, while theoretical studies of double-spiral cut haverarely been found in the existing literatures. Therefore, based on the drifting project ofXiangtan Manganese Ore Company, research on blasting mechanism of double-spiral cut andoptimization of cutting parameters is carried out. The main achievements of this thesis are asfollows:(1)Through theoretical analysis of the distance between first blasting hole and emptyholes, a new way of hole pattern which sets the empty holes in the crushing circle of the firstblasting hole charge has been presented. In the case of low drill precision, the cutting successrate can be improved.(2)The explosion of40mm diameter No.2rock modified ANFO cylindrical charge isnumerical simulated with ANSYS/LS-DYNA3D, and the radius of crushing circle in limestonehas been worked out as9cm.(3)Formula of blasting hole depth is deduced on the basis of Livingston blasting cratertheory and equivalent burden theory of cylindrical charge blasting.(4)The explosion of seven models of cutting holes with different extra-deeps arenumerical simulated with ANSYS/LS-DYNA3D, and the result indicates that the bestextra-deep of cut holes under the simulated conditions is15cm. Comparing stress variationrules of rock at the bottom of cut holes for seven models, find that stress field intensity has nolonger increased when the extra-deep reaches a higher value, and the ultra-deep is the criticalultra-deep at this time; Rock crushing at the bottom of cut holes is achieved when theultra-deep reaches a certain minimum value which is less than or equal to the criticalextra-deep, and the extra-deep is the best extra-deep at this time.(5)The double-spiral cut blasting parameters for the driftage project of XiangtanManganese Ore Company are designed. After the blasting text, drifting footage and blastingefficiency have been improved to88.33%and22.5%, and the cutting success rate has reached 100%. This research achieves good results in engineering practice.