Question

Explain how confinement affects detonation properties, specifically in non-ideal high explosives.(Using Annual Review of Fluid Mechanics
High Explosive Detonation–Confiner Interactions for reference).

Answer 1

The primary purpose of a detonation in a high explosive (HE) is to provide the energy to drive a surrounding confiner, typically for mining or munitions applications. The details of the interaction between an HE detonation and its confinement are essential to achieving the objectives of the explosive device. For the high pressures induced by detonation loading, both the solid HE and confiner materials will flow.
The structure and speed of a propagating detonation, and ultimately the pressures generated in the reaction zone to drive the confiner,
depend on the induced flow both within the confiner and along the HE–confiner material interface.
A new model to predict the non-ideal detonation behaviour of commercial explosives in rock blasting is presented.
The model combines the slightly divergent flow theory, polytropic equation of state, simple pressure-dependent rate law and statistical expressions to model the effect of confinement on detonation.
The model has been designated as DeNE, an acronym for the Detonics of Non-ideal Explosives. It is aimed at predicting the detonation state and subsequent rarefaction (Taylor) wave to provide the pressure history for different explosive,
rock type and blasthole diameter combinations.
It enables the prediction and comparison of the performance of commercial explosives in different blasting environments.
The unconfined detonation velocity data has been obtained from the testing of six commercial explosives to calibrate DeNE.
A detailed sensitivity analysis has been conducted to evaluate the model.
The model has been validated using the results of hydrocodes as well as measured and published in-hole detonation velocity data.
The detonation–confiner interactions are heavily influenced by the material properties and, in some cases, the thickness of the confiner.
This review discusses the use of oblique shock polar analysis as a means of characterizing the possible range of detonation–confiner interactions.