Response of Granular Materials Towards Blast Loading

Abstract

Granular media, such as sand, soil, and rocks, are commonly encountered in various engineering and geotechnical applications, and their response to blast loading is of significant interest. In this master’s thesis, the attenuation characteristics and equation of state of granular media subjected to different blast wave loadings are investigated. Experimental investigations are conducted to determine the attenuation characteristics of granular media subjected to blast loading. A series of laboratory-scale experiments are performed using a shock tube apparatus to generate controlled blast waves. Granular media samples of different types (naturally available sand and artificially generated glass beads) are subjected to different blast wave loadings. The response of the granular media, including the transmitted pressure and impulse, is measured using pressure sensors. The experimental results are analyzed to determine the attenuation characteristics of the granular media, including the attenuation coefficient, the influence of blast wave parameters and packing density of the granular media on the attenuation. It was discovered that the extent of attenuation was higher when blast waves impinged on sand samples with 43 % relative density compared to the scenario when the sand samples were packed to 25 % relative density. The range of attenuation coefficient is (-4.70 to -7.48) for 25% relative density sand samples and for experiments done on 43% relative density sand samples it was found to be in the range (-5.12 to -8.88). Furthermore, experiments have been conducted to come up with equation of state (EOS) to describe the behavior of granular media under blast loading. The EOS relates the change in granular media properties, such as particle velocity, to the applied blast wave loading. The parameters of the EOS are determined using the experimental data obtained from the high-speed imaging experiments. Relationship among particle velocity UP , wave speed US and pressure P described by following equations together is a basic equation of state for sand compacted till 43 % relative density as the granular media when subjected to blast loading of varying intensities. The findings of this research contribute to a better understanding of the response of granular media to blast loading and provide valuable insights for engineering and geotechnical applications where granular media are subjected to blast loads. The results also highlight the importance of blast wave characteristics and granular media properties in determining the attenuation behavior and equation of state of granular media under blast loading. Further research opportunities are identified, including the validation of the EOS using field-scale experiments and numerical simulations.