Hydrodynamic Modeling of Air Blast Propagation from the Humble Redwood Chemical High Explosive Detonations Using GEODYN

Chipman, Veraun

doi:10.2172/1035964

Cited by 3 publications

(1 citation statement)

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“…The framework could be improved by testing the chemical‐nuclear equivalence assumptions for near‐surface events. Numerical experiments using material models trained on observations of chemical explosions could be used to predict the effects of large nuclear explosions (Chipman, 2011). And high energy density laser experiments could fill in experimental gaps between chemical and nuclear explosions (Fournier et al., 2014).…”

Section: Discussionmentioning

confidence: 99%

Joint Bayesian Inference for Near‐Surface Explosion Yield and Height‐of‐Burst

et al. 2021

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Explosions near the Earth's surface excite seismic motion in the ground, acoustic overpressure in the atmosphere, and optical irradiance in the air. Since geophysical observations of an explosion scale with the explosion size, features related to the seismic, acoustic, and optical observations can be used to infer the explosion size, or yield. There are many studies on the relationship between an explosive source and the resulting ground motion, air blast, and fireball to better understand their damaging effects in a forward sense (Glasstone & Dolan, 1977). However, the combined use of the explosion effects can also be used in the inverse sense (Arrowsmith et al., 2010). For example, Sabatier and Raspet (1988), and later Albert et al. (2013), showed that coupled observations of seismic ground motion and acoustic air blast aid in the understanding of damage from artillery blasts. And Kitov et al. (1997) looked at acoustically induced surface waves for inference of explosive yield and propagation medium properties. Many seismoacoustic inverse studies have to overcome incomplete joint data sets and Stump et al. (2004) showed the benefit of designing arrays that measure the complete seismoacoustic wavefield. A combined approach is especially important when estimating yield for events near the surface. Near-surface interactions will alter the outgoing wavefield such that there is a trade-off between the height-of-burst (or depth-of-burial) of an explosion and its inferred yield. When an explosive source is buried its seismic signal is maximized but its acoustic and optical signals are minimized. When that source is above-ground its acoustic and optical signals are increased but its seismic signal decreases. Therefore, any estimate of near-surface explosion yield must include an estimate of height-of-burst, and these estimates must be made using a combination of seismoäcoustoöptic observations to "break" the trade-off between yield and height-of-burst for any single type of observation. Building on the work from Koper et al. (1999), Koper et al. (2002) analyzed truck bomb explosions and determined relationships between seismic and acoustic observables and yield. They investigated several different features derived from seismic and acoustic observations and found that acoustic observations were the most robust with the impulse per unit area as the least biased measurement. Ford et al. (2014) used their

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Section: Discussionmentioning

confidence: 99%

Joint Bayesian Inference for Near‐Surface Explosion Yield and Height‐of‐Burst

et al. 2021

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Airblast observations and near-field modeling of the large surface explosion coupling experiment

Vorobiev,

Ford

2024

International Journal of Protective Structures

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Seismoacoustic wave generation for two consecutive surface chemical explosions of the same yield (approximately 1 ton TNT-equivalent) was studied during the Large Surface Explosion Coupling Experiment (LSECE) conducted at Yucca Flat on the Nevada National Security Site (NNSS) site in alluvium geology. We have performed numerical simulations for both chemical explosions to investigate how the non-central source initiation, site topography and soil mechanical properties affect the evolution of the explosion (fireball and cloud), its crater, and variations in the generated blast waves. The results can be used to improve the understanding of surface explosions and their effects and how those effects can be used to infer source information such as explosive yield and emplacement. We find that the non-central detonation of the explosive cube results in non-axisymmetric blast overpressures which persist through the strong and weak shock regimes, in this case out to 200 m and more. The pattern of the secondary shock (i.e., shock created due to slowing explosive products within the expanding fireball) is also affected and its arrival relative to the main shock and may be indicative of explosive type due to its dependence on the explosive products ratio of heats. Small reflections are visible within the overpressure signal that are most probably due to small artifacts in blast path. Importantly, the fireball growth, cavity generation, and cloud formation also depart from spherical and ideal approximations due to ground interactions and material dependence, which shows the importance of realistic geomaterial models for accurate prediction. The asymmetry in peak overpressure is diminished for the second chemical explosion, which was placed in the crater of the first. Numerical modeling shows that the explosive jetting created by the non-central detonation is reduced upon interaction with the crater walls and this has the effect of making the blast generation more axisymmetric.

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Numerical Modeling of Air-Blast Suppression as a Function of Explosive-Charge Burial Depth

Ford

Vorobiev

2023

Bulletin of the Seismological Society of America

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As a chemical explosion is buried, the mechanism for acoustic wave generation transitions from fully gas-generated at the surface to completely spall-induced at full containment depth. The fully gas-generated and completely spall-induced signals in the acoustic waveform are well described; however, the transition between these two end-members eludes numerical modeling because of the complex phenomena that are involved. The phenomena of crater formation and explosive cloud evolution are simulated using an Eulerian hydrocode that incorporates geomaterials with strength and porosity. Having accurately modeled these phenomena, we can confidently predict the propagation and relative strength of the gas-generated and spall-induced pulses in the recorded acoustic waveform. The numerical predictions agree with observations from the historical Stagecoach experiment as well as modern recordings from the Source Physics Experiment. In particular, the peak pressure p generated by an explosion is initially due to the gas-generated mechanism and decays with scaled depth of burial ds (depth d scaled by the cube-root of explosive yield w1/3) as exp(−ds) but then transitions near a scaled depth of 6 m/ton1/3 to the spall-generated mechanism in which the decay is ds−7/4. This decay form is related to the strong ground-motion attenuation relationship that affects spall strength. These results can improve seismoacoustic inverse models for the explosive source that need to account for the gas-generated and spall-induced signals and their effect on peak pressures and other acoustic signal features.

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Hydrodynamic Modeling of Air Blast Propagation from the Humble Redwood Chemical High Explosive Detonations Using GEODYN

Cited by 3 publications

References 1 publication

Joint Bayesian Inference for Near‐Surface Explosion Yield and Height‐of‐Burst

Joint Bayesian Inference for Near‐Surface Explosion Yield and Height‐of‐Burst

Airblast observations and near-field modeling of the large surface explosion coupling experiment

Numerical Modeling of Air-Blast Suppression as a Function of Explosive-Charge Burial Depth

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