円筒形爆薬の爆発に対する岩盤の動的応答について

抄録

In this paper, the behaviors of stress waves in infinite rock-media produced by each explosion of various cylindrical charges were analyzed by the theory of elasticity. According to the results obtained, if the peak values of various types of bore-hole pressures are equal, a bore-hole pressure with longer rise-time causes more drastic decay of the compressive peak-value of the radial stress wave as the distance from the bore-hole increases. On the other hand, the decay of the tensile peak-value of the circumferential stress wave has nothing to do with the rise-time, but it has relation to the total shape of the borehole-pressure curve. Furthermore, the bore-hole pressure which makes the decay of the former peak-value small does not always correspond to the pressure which makes the decay of the latter peak-value small. Thus, it can be realized that for a given blasting method, there is an optimum bore-hole pressure, namely an optimum explosive or an optimum charging method:
If the rocks broken by blasting are assumed to have Poisson's ratio of 0.2-0.3, the induced stress waves in the rock-media are not affected very much by the change of Poisson's ratio. As Poisson's ratio increases, the wave-lengths of the stress waves are slightly elongated, and the absolute values of both the compressive and tensile peaks are slightly increased except for the case of a bore-hole pressure with an infinitely short risetime, where the compresive peak value of the radial stress wave has no relation to Poisson's ratio.