Predicting the effects of explosions placed on the earth's surface

Date
2020
Authors
Grobbelaar, Michelle Robyn Garvin
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Abstract
Many predictive equations within literature are focused on explosions within the ground such as mining blasts and tunnelling. According to the United States Code of Federal Regulations (30 CFR part 816.67 of 1998), the recommended equipment to monitor buried explosions, are geophones. Other equations which examine surface explosions utilise a number of specialised equipment in addition to the seismograph equipment used for monitoring buried explosions, such as microphones and pressure gauges. The aim of this study is to determine whether or not one could use predictive equations for buried explosions to predict the effects from surface explosions by merely using data obtained from a small network of surface installed seismograph stations. Military demolition sites are areas where old and potentially unstable explosives and obsolete equipment are destroyed and the ordnance is placed on the surface of the ground and detonated. The ordnance is seldom buried and thus modelling and predicting the ground vibrations and shock waves should consider predictive equations for both ground waves and atmospheric shock waves. The modelling can assist in preventing damages to surrounding infrastructure and injury to people in the vicinity. These equations could similarly be utilised for assisting in forensic seismology to determine the details of unexpected explosions, such as gas pipelines, silo explosions and vehicle bombs. By combining the various equations available, this study has identified a number of predictive equations which have produced acceptable results when examining data obtained from military ordnance demolitions on the surface. In general, the values for atmospheric shock waves are easier to determine than those from the ground motion because the atmospheric shock waves are more prominent on the seismograms than those of the ground motion, due to the fact that very little of the energy is transmitted into the ground. Therefore, utilising atmospheric shock wave measurements may be more useful because the ground motion waves are not clearly recorded. The study has shown that the USBM peak particle velocity (PPV) predictive
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A dissertation submitted to the Faculty of Science, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science, 2020
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