Dynamic simulation approach to assess influence of charging parameters on blast induced vibration

摘要

Blast induced ground vibration is one of the key concerns from safety view of nearby structures. There are many direct and indirect parameters responsible for blast induced ground vibration. Explosive parameters including its charging quantity and quality is one of them. Velocity of detonation of explosives, its interaction with rock strata and charging condition of a blasthole influences blast outputs in the form of fragmentation as well as undesirable effects like ground vibration, flyrock, air-over-pressure/noise etc. Researchers around the globe have established empirical formulations to investigate effects of explosive parameters on blast induced ground vibration. Following paper focused on investigating influence of charging parameters on blast induced ground vibration. Numerical simulation using dynamic modelling package of FLAC3D have been used for this. Signature hole geometry with rock properties and explosive properties in the form of detonation pressure has been modelled. Detonation pressure of the explosive was estimated from recorded in-the-hole velocity of detonation and density data for different explosive types. Damping parameters in the form of damping coefficient and frequency has been given to deplete blast vibration velocity for the medium. This was estimated by back calculation from recorded blast vibration data. Influence of hole diameter, distance of blast face from monitoring point, column length of explosive charge and charge distribution on blast induced vibration were assessed. Blast induced ground vibration in the form of history of velocity peaks has been plotted against dynamic time of blast wave propagation. Results of the dynamic simulation shows effects of hole diameter and charge column length on blast vibration in the same line with explosive weight per delay considered in USBM predictor equation. Investigation of effects of distance on blast induced vibration shows dependency of blast vibration on directional distance rather than radial distance. Charge distribution effects shows considerable reduction in blast vibration magnitude for distributed charge than full column charge.