大発破に関する研究(II) ―爆破点近傍の振動測定―

The ground motions near shot point are measured at various places, that is, in the quarryand on the ground surface of each different geological structure. The weights of charge are inthe range of 0.1-1 tons and the distances from shot point and measure points are 20--~--120 in.It is confirmed that the displacement, particle velocity and acceleration of the ground motioncaused by explosion are largely related to the blasting conditions, geological structure of themeasure point and the path through which the waves passes. Especially, the tainping of thecharge and the shape of the free surface before the blast are mainly concerned with the emis-sion of elastic waves from the shot point. The size of rock fragments after the blast is foundto be a function of C which is expressed by C=a/W'/'d'. (a: amplitude, W: weight of charge, d: distance between shot point and measure point.)The ground motions near shot point are measured at various places, that is, in the quarryand on the ground surface of each different geological structure. The weights of charge are inthe range of 0.1-1 tons and the distances from shot point and measure points are 20--~--120 in.It is confirmed that the displacement, particle velocity and acceleration of the ground motioncaused by explosion are largely related to the blasting conditions, geological structure of themeasure point and the path through which the waves passes. Especially, the tainping of thecharge and the shape of the free surface before the blast are mainly concerned with the emis-sion of elastic waves from the shot point. The size of rock fragments after the blast is foundto be a function of C which is expressed by C=a/W'/'d'. (a: amplitude, W: weight of charge,d: distance between shot point and measure point.

大発破に関する研究(I) ―発破計画および爆薬について―

In order to discuss about the method and the explosives for the coyote blasting and also themethod for verifying whether whole charges have been detonated or not, a specially designedcoyote blasting was carried out at Maeshima, Ushimadocho Okayama prefecture, on 18th April1962.Rocks around test site is a kind of granite. In this blasting, 11 chambers were formedwithin rocks and these were filled up with proper explosives. Total weight of explosives filledup in these chambers were about 6, 500 kg, and these explosives were fired by some delay de-tonators. The time from the instant of detonation of the initial chamber to that of the last wasabout 4, 000 ins.Some high speed moving camera and some pick-up which were used for observing the vi-bration of rocks caused by these explosions were used for verifying the detonation of each ex-plosive.It was recognized on this coyote blasting that the breakage of rocks by the delay blastingwas better than that by the instantaneous blasting, therefore, the delay blasting was useful inthe coyote blasting as same as the general blasting which was performed by the explosives load-ed in some drill holes, and also the verification of detonation was more easily on the delayblasting, therefore, adopting the delay blasting method to the coyote blasting was available onthe stand point of safety in operations.In order to discuss about the method and the explosives for the coyote blasting and also themethod for verifying whether whole charges have been detonated or not, a specially designedcoyote blasting was carried out at Maeshima, Ushimadocho Okayama prefecture, on 18th April1962.Rocks around test site is a kind of granite. In this blasting, 11 chambers were formedwithin rocks and these were filled up with proper explosives. Total weight of explosives filledup in these chambers were about 6,500 kg, and these explosives were fired by some delay de-tonators. The time from the instant of detonation of the initial chamber to that of the last wasabout 4,000 ins.Some high speed moving camera and some pick-up which were used for observing the vi-bration of rocks caused by these explosions were used for verifying the detonation of each ex-plosive.It was recognized on this coyote blasting that the breakage of rocks by the delay blastingwas better than that by the instantaneous blasting, therefore, the delay blasting was useful inthe coyote blasting as same as the general blasting which was performed by the explosives load-ed in some drill holes, and also the verification of detonation was more easily on the delayblasting, therefore, adopting the delay blasting method to the coyote blasting was available onthe stand point of safety in operations