A method of protecting roofs of drifts during blasting operations in a deep mine.

摘要

A method of protecting roofs of drifts during blasting operations in a deep mine, characterised in that, first, testing and a calibration blast is carried out in the mining district and measurements of the seismometricly maximum speed of immediate roof vibrations at various distances from the explosive blasted in the working face. The values of coefficients of the equation of the scaled distances are determined on that basis; they express the numerical relation between the speed of vibrations, the weight of explosive blasted simultaneously and the distance from the centre of mass of the explosive to the vibrations measurement point. Further, in the working face, there is applied a pre-determined maximum weight of the total explosive per effective milidelay, which, after blasting, produces vibrations of the roof of the closest excavation or a crossing of excavations with vibrations speed not causing boundary value characteristic of a roof damage or destruction.