岩石内における爆破点近傍の波動の伝播及びそれに伴う破壊について(I)

Abstract

The basic character of fracture and plastic deformation processesthat will be operative under extremely high, yet very transitory pressure, imposedon rock by explosion is studied experimentally. The mode of propagation of tran-sient disturbance is measured by seismometric pick up and strain gage especiallydevised for this purpose put within the fracture zone and neighboring plastic zonewhich would be formed by explosion. Magnetic tape recording system is used par-tially and play back record are obtained with several ranges of filtering.The strain wave shapes, that is, the rise time, the pulse width, etc., are shownto be influenced by applied pressure, the distance from the shot point and free surface;moreover, these pulses are composed by component waves different in propagatingvelocity. The experimental results are discussed referring to the stress strainrelation of each rock determined statically by experiment. In the very neighbourhoodof shot point two different kinds of waves are detected. One is the elastic wave ofrelatively higher frequency and the other the plastic wave of lower frequency. Withthe increase of amount of explosive the propagating velocity of the plastic wave iseffected and becomes slower.