Abstract: The bunch-holes equivalent spherical charge blasting belongs to a mass caving blasting technology. It can comprehensively combine the optimal charge depth of blasting crater with the bunch-holes blasting effect which can enhance blasting energy in the intermediate and far field from blasting point， so that the blasting efficiency can be increased sharply. It is applied in several mines and has achieved good technical and economic effects. In this paper， blasting crater tests of bunch-holes equivalent spherical charge with different charge depths were done and crater volumes were scanned precisely by 3D laser scanner. Then， the relationship between charge embedding depth and crater volume was established， based on which the best embedding depth was obtained. Analyzing the relationship between the embedding depth ratio and crater volume per unit explosive， the blasting crater curve was fitted by Gauss function， so the Gauss formula of blasting crater was gained. The influences of blasting releasing energy per unit explosive， rock tensile strength， charge depth and energy utilization ratio of explosive on bunch-holes equivalent spherical charge blasting were analyzed，which can offer a quantitative characterization method for blasting effect evaluation of bunch-holes.The bunch-holes blasting parameters composed by 4 and 5 holes were calculated respectively， and the optimal charge embedding depth of bunch-holes blasting was determined based on the fitted Gauss curve model and the results of blasting crater tests. The results of this paper can provide a technical reference for design of bunch-holes blasting.

Key words: bunch-holes, equivalent spherical charge, blasting crater, Gauss curve fitting model