1939 Where: Ωmax = Higher natural frequency of the system. ξ = Fraction of critical damping corresponds to the highest frequency. To couple the pressure generated by the gases produced by the detonation of the explosives, only the pressures on the surfaces are interpolated with the discrete elements for each timestep and by means of an iterative process, the interaction of the discrete elements in the gas mesh is recalculated. Figure 3 shows the cyclical operation of calculation. Illustration 4; Coupling of the gas flow with discrete elements (Minchinton & Lynch, 1197). USE OF ELFEN PROGRAM FOR PRESPLIT CALCULATION WAVE THEORY As indicated in previous points, ELFEN simulates the detonation of explosive charges in a blasthole and the effect of gas pressures, expanding in the rock mass around the blastholes. To develop a presplitting model, it is necessary to have rock mass strength data with their respective structural sets and the properties of the explosive to be employed for this technique. Regarding respect to the parameters of the explosive, we need to know: VOD, density, effective energy, Relative Weight Strength (RWS), and Relative Bulk Strength (RBS). Under a Cpex model (Esen S, 2005; Minchinton, 2015; Louw, 1993), the pressure parameters are defined as a function of the rock strength and the confinement diameter. Since this method includes a confined explosive, it is necessary to make a modification to the detonation pressure, which is given by the following expression.
RkJQdWJsaXNoZXIy MTM0Mzk2