Design of Effective Blast Design as A Mitigative Measure Against Ground Vibration Based On Numerical Modelling- A Case Study

Abstract

Blasting is a major operation in mining activity. It is the most convenient method for fragmenting the hard strata for removal of coal and mineral. In spite of the emergence of many blast free technology including surface miner, vibro-ripper, etc blasting still dominates over them due to its cost effectiveness and productivity. Large opencast mines across India uses tons of explosives annually for removal of over burden material. Use of large volume of explosives with improper blast geometry, delay sequence, selection of drills etc may lead to environmental hazard in terms of ground vibration leading to damage of many civil and earthen structures. Blast wave propagation along a rock strata has a damaging impact on the structures built across it when there is resonance of blast wave frequency with that of natural frequency of the structure concerned. Ground movement can be ascertained by measuring the ground displacement, velocity or acceleration by the geophones or seismographs. DGMS, the mine safety watch dog of India has laid down guidelines suggesting limiting criteria of Peak Particle Velocity based on the dominating frequency ranges for various civil structures. This paper discussed the mechanism of blast wave propagation in a mine strata with the use of numerical modelling software in continuum approach