Inclined boreholes as a means of leveling the base of the ledge at granite quarries

Abstract

At quarries of the Leningrad region granite stripping is conducted, placing charges of explosives in vertical wells in diameter of 105 mm. Usually after explosions the bottom of a ledge turns out extremely uneven, ledges (sills) sometimes reach one third of height of a ledge. Due to the uneven bottom of the ledge productivity of excavators EKG-4 does not exceed 250 thousand m^3/ year, ie about half as much as at the advanced mining enterprises.