Spherical charge cratering—plane and angle geometry involving small-scale single and row tests

CIM Bulletin, Vol. 74, No. 829, 1981

R.R. MacLACHLAN, D.E. SALMAN and R.J. BARCLAY, Department of Mining and Metallurgical Engineering, McGill University, Montreal, Quebec

There is a considerable resource of data for spherical charge cratering, both as single  charges  and  in   row-of-charge geometry. The data are, however, based on cratering performance to a single free planar surface.In practice, the more common circumstance involves an angular surface geometry, such as occurs at the toe of a bench or the wall of aslope. It is for the purpose of investigating this circumstance that the described test work was conducted.The test objectives were: (1) to observe the change in single-charge cratering performance between plane-surface and angle geometry; (2) to identify the optimum performance of single charges cratering to a plane surface, cratering from a bench sub-grade position and cratering from a condition of zero sub-grade or slope wall geometry; and (3) to observe the performance of row-of-charges cratering to an angular surface at various row burials and spacing. The row charge burial and spacing dimensions were to be expressed in simple numerical multiples of single-charge depth-of-burial data.
Keywords: Open-pit mining, Cratering, Spherical charge cratering, Blasting, Benching, Rock mechanics, underground mining.