Simulation of the generation and propagation of blast induced shock waves
Hybrid modelling of blast vibration uses the signal produced from a single hole test shot to simulate the vibration that would be produced by a full-scale production blast. This simulation can be used to determine optimum hole timings to minimise the vibration generated at a point of interest. This thesis studies the assumptions that are made to facilitate the use of hybrid modelling with emphasis placed on near to mid field applications. A highly accurate seismograph is developed and used to monitor a series of test blasts carried out in limestone and chalk. The repeatability of single hole test shots is investigated. It is shown that in the near field single holes are generally highly repeatable even with relatively major differences in design. It is also shown that an inversion of the radial and transverse vibration traces may occur. The factors which affect the vibration magnitude are also explored, showing that the level of confinement can have a large effect on the magnitude of vibration. Two, three and five hole production blasts are examined to determine the signal generated by each hole in the blast. It is shown that in a two hole blast the second hole can produce an inverted signal in the radial and transverse components. The three and five hole are disassembled by using a computer program to test every possible combination of convolved single holes and select the best. It is concluded that the complex interaction of the vibration generated by each blast hole makes it very difficult to model the vibration generated by a production blast in the near field.