Commercial explosives exhibit non-ideal detonation behaviour since their performance is influenced by blasthole diameter and confinement. Although the laws governing the physico-chemical nature of non-ideal detonation in mathematical form have been known for over 50 years, there is yet no established method of analysing the problem such that it can be solved approximately with acceptable accuracy.
The principal objective of the research was to develop a hybrid non-ideal detonation model combining the proven non-ideal detonation theory (slightly divergent flow analysis), polytropic equation of state, simple pressure dependent rate law and statistical expressions which takes into account the confinement effect on detonation.
The model developed in this study is named the 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 the commercial explosives in different blasting environments (i.e. explosive and rock type, blasthole diameter). Furthermore, it provides the means of quantifying the explosive loads along the explosive column using the pressure history. These data can be used in any empirical to fundamental blasting models to model the blasting process.
Data required to run DeNE are explosive properties (ideal detonation parameters, unreacted explosive properties, unconfined VoD versus charge diameter data), blasthole diameter and intact rock data (density and P-wave velocity). The proposed model should provide acceptable representations of the behaviour of commercial explosives for rock blasting applications.
Six commercial explosives including ANFO, Heavy ANFO and blend type explosives have been tested to obtain a wide range of unconfined VoD versus charge diameter data. A total of eight in-hole VoD tests for four commercial explosives were collected from four mines. These have been used to calibrate and validate DeNE.
A detailed sensitivity analysis was carried out for the key identified input parameters in DeNE. The influences or relative, importance of each input factor on the output variables as well as the uncertainties in the input parameters are analysed in detail for ANFO, blend and emulsion explosives.
The sensitivity analysis is further extended to investigate the potential impact of blasthole diameter, explosive type, rock properties, Taylor wave model and the variations in the unconfined VoD and density of the explosive on the detonation state results. The sensitivity study conducted using a model made available by Braithwaite et al. (1989) has enabled a critical analysis on the unreacted equation of state, shock calculation method and rate law. The results of the code are compared with that from detonation shock dynamics theory. The DeNE has been validated using the results of the hydrocodes and the non-ideal detonation model developed by Braithwaite et al. (1989) as well as the measured and published in-hole VoD data. It is shown that the results of the DeNE compares well with these codes. The DeNE is further validated using in-hole VoD data which suggests that the average error in predicting the confined VoD is within the experimental error.