Effect of explosive charge-blast distance interaction on ground damage (Boukhadra mine, Algeria)

Kamli, O.; Boutaleb, A.; Hacini, M.; Djouama, M. C.

Purpose. The aim of this research work is to assess the effect of the explosive charge and the blast distance on the stability of the Boukhadra iron mine. The objective is to contribute to the conception of a blasting plan in order to reduce the effect of the vibrations on the slope stability and ground damage. Methodology. The characterisation of the blasting process was done using geophones to record the particle velocity for sixteen tests, and the DELTA SEIS software to determine the ground displacement influenced by the particle velocity. We also used the PLAXIS 8.2 software to simulate the slope stability under the effect of blasting by calculating the safety factor for the entire mine. Findings. We concluded that the blasting itself is not the main cause of the slope instability, since the cause of instability is conditioned by structural, blend and phase composition of slope rocks and peculiarities of physicochemical interaction with propagating blast and elastic waves caused by explosive charge blast. Originality. Numerical simulation of ground displacement under the effect of blasting was performed with the use of two different tools: geophones assisted by the Delta SEIS characterising certain blasting results and the PLAXIS 8.2 software. It was found that "the mass of explosive charge - explosive charge-blast distance" being 130 kg and 177 m respectively leads to a peak particle velocity of 16 mm/s and acoustic overpressure of 147 dB causing a ground displacement of <$E 335~mu roman m>. Practical value. The results are used while preparing technical specifications for conducting drilling-and-blasting operations, which allowed increasing slope stability regarding the effect of blast and elastic waves significantly. In the process of stimulation we found that we found that a safety factor Fs is 0,90 (less than one), which certainly leads to the slope sliding.


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