Abstract:

Based on the outdoor blasting experiments, mid and far field pressures of explosive stress waves are measured using self-made PVDF pressure sensor under the condition of couple charges and water-decouple charges. Whereafter, the attenuation exponent relationships between explosive stress wave amplitude and distance of the wave front from the blasting source in the case of four different decouple coefficients are fitted according to experimental results. The conclusions are drawn as follows. ①In blasting experiments involved range, the attenuation of explosive stress wave amplitude of decouple charge is less than those of couple charge (namely K =1). According to this result, it is verified that water is suggested as an elastic buffer between detonation products and rock which decreases dissipation of explosive energy caused by crushing the rock surrounding a charge, increases the propagation of explosive energy and enlarges the action region of explosive stress wave. ②The attenuation exponent of explosive stress wave amplitude when decouple coefficient equal to 3.29 is more than those when decouple coefficient equal to 1.79 and 2.57. It is shown that decouple medium (namely water) induces excess dissipation of explosive energy when decouple coefficient is too large, because water is non-perfect elasticity medium under high temperature and high pressure. This weakens the advantage of decouple charge blasting. ③There is an optimal decouple coefficient in the decouple charge blasting. At this moment, in contrast with couple charge and other decouple charge; the explosive stress wave amplitude attenuates most slowly; the explosive energy can be fully utilized; and then the best blasting result will be obtained. The study results have some guiding significance for design of decouple charge blasting and its engineering application.

Key words: decouple charge, blasting experiments, explosive stress wave, propagation law, PVDF pressure sensor