• Journal of the Korea Concrete Institute
• /
• v.25 no.1
• /
• pp.107-114
• /
• 2013

In this study we experimentally evaluated an impact resistant performance of fiber reinforced concrete in the moment of explosion by high-velocity projectile with emulsion explosive. To assess the impact resistance, we conducted the impact test of high-velocity projectile which reaches an impact speed of 350 m/s and the experiment of contact exploding emulsion explosive. As a result, bending and tensile performance depending on type of PVA, PE fiber (polyvinyl alcohol fiber, polyethylene fiber) and steel fiber affects destruction of rear side in the form of spalling. Destroying the backside of the concrete compressive strength compared to suppress the bending and tensile performance is affected. In addition, the experiment shows that the destruction patterns of concrete specimen producted by high velocity impact and contact explosion are significantly similar. Therefore, it is possible to predict the destruction patterns of specimens in the situation of contact explosion by high-velocity projectile.

• Explosives and Blasting
• /
• v.40 no.3
• /
• pp.33-43
• /
• 2022

In order to minimize the impact on the structure during an internal explosion, the explosives storage must be kept at a distance from the inner wall to prevent the sympathetic detonation of the others explosives in an unexpected explosion. For safe explosives storage, a gap test was conducted by simulating the split arrangement of explosives inside the storage. In this study, the separation distance and arrangement between the emulsion explosives were applied differently to be sympathetic detonation at 2D of diameter and non-detonated at 2.5D. Considering the coefficient of detonation transmission and the size of the explosives storage, the explosive amount of 3kg was set, and most of the gap tests according to various arrangement changes were non-detonated, and safety was confirmed when applying the batch.

• Explosives and Blasting
• /
• v.24 no.2
• /
• pp.23-31
• /
• 2006

Optimum additive which gets Possible detonation sensitivity and minimum stability has been selected among several additives. It is able to mitigate a chemical reaction without destroying a structure of emulsion. Kinecker has been developed by mixing both matrix and selected additive through a perfect formulation. The detonation pressure is reduced by 40.66%(47.27% by Nitro Dyne's program), and hole pressure by 33.25% and even VOD by 52.88% against currently used emulsion explosives.

• Explosives and Blasting
• /
• v.35 no.4
• /
• pp.19-26
• /
• 2017

The most widely used method for determining the blast effects of explosives is the Trauzl lead block test. This test is used to measure the explosive power (strength) of a substance by determining volume increase, which is produced by the detonation of a test explosive charged in the cavity of a lead block with defined quantity and size. In this paper, Trazul lead block test and AUTODYN numerical analysis were conducted to evaluate the coupling medium effect of blast hole. The effects of coupling materials can be expressed as the expansion of the cavity in a standard lead block through explosion of the explosives. The tests were conducted with emulsion explosives. The coupling mediums used as the filling material around a explosive charge were air, sand, water and gelatine. Results of test and numerical analysis showed that expansion of lead block were much more affected by water&gel than by sand and air. The water and gel showed similar results. As expected, the transmitted pressure and dynamic strain was higher in water and gelatine coupled blast hole than in air and sand.

• Explosives and Blasting
• /
• v.20 no.3
• /
• pp.7-13
• /
• 2002

제 5세대의 안전화약이라고 부르는 에멀젼폭약은 고전적인 폭약의 개념을 불과 수년 사이에 크게 바꾸어 놓았다. 그러나 정밀화학공업이 상당한 수준에 이르고 있는 현시점에 가장 핵심적인 기술에 속하는 에멀젼폭약의 계면활성저에 대한 국내 연구 발표사례는 전무한 실정이다. 에멀젼폭약의 기본 이론인 왁스 성분과 수분과의 상관관계에 결정적인 역할을 하는 계면활성제에 대한 꾸준한 연구결과 HLB 3~9 범위 중 4.3에 속하는 Span80 이라는 S.A.A가 가장 양호한 결과를 나타내었다. 아울러 기존 생산시스템의 작업온도 $90^\circ{C}$보다 훨씬 낮은 $60^\circ{C}$전후에서도 생산이 가능하다는 실험적 결론을 얻을 수 있었다.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2016.05a
• /
• pp.128-129
• /
• 2016

This paper evaluates experimentally the explosion proof of fiber reinforced cement composite(FRCC) panels with various fibers of 2 % volume fraction subjected to contact explosions using an emulsion explosive. As a results, the proportion of the total damage in FRCC panels is not biased scabbing on the rear side with contrast to plain panels, which means that the local damage of FRCC panels was significantly controlled. The experimental results presented useful information for prediction of limited thickness on the local damage subjected to contact explosions through comparison with existing damage evaluation prediction equations.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.5 no.4
• /
• pp.337-348
• /
• 2003

The propagation mechanism of a detonation pressure with fully coupled charge is clarified and the blasting pressure propagated in rock mass is derived from the application of shock wave theory. The blasting pressure was a function of detonation velocity, isentropic exponent, explosive density, Hugoniot parameters, and rock density. Probabilistic distribution is obtained by using explosion tests on emulsion and rock property tests on granite in Seoul and then the probabilistic distribution of the blasting pressure is derived from the above mentioned properties. The probabilistic distributions of explosive properties and rock properties show a normal distribution so that the blasting pressure propagated in rock can be also regarded as a normal distribution. Parametric analysis was performed to pinpoint the most influential parameter that affects the blasting pressure and it was found that the detonation velocity is the most sensitive parameter. Moreover, uncertainty analysis was performed to figure out the effect of each parameter uncertainty on the uncertainty of blasting pressure. Its result showed that uncertainty of natural rock properties constitutes the main portion of blasting pressure uncertainty rather than that of explosive properties. In other words, since rock property uncertainty is much larger than detonation velocity uncertainty the blasting pressure uncertainty is more influenced by the former than by the latter even though the detonation velocity is found to be the most influencing parameter on the blasting pressure.

• Explosives and Blasting
• /
• v.28 no.2
• /
• pp.69-75
• /
• 2010

Excavations by blasting in urban area have caused lots of complaints. Hence, special attentions need to be paid to controlling the ground vibrations in designing blasting for those areas. In this study, among the various parameters that can affect the propagation characteristics of ground vibrations, the effect of the priming location of explosive on the ground vibration level was studied for two types of emulsion explosives that had different detonation velocities. Three priming locations of top, middle, and bottom were considered in a charged hole. In the experiment on the effect of detonation velocity, the ground vibration caused by the explosive with a lower detonation velocity showed larger attenuation in the amplitude. The priming locations also affected the ground vibrations levels. The ground vibration level produced from middle priming was found to be larger than the other priming methods under the same blast conditions, but the attenuation of amplitude was also larger in this case. In contrast, the ground vibration level from bottom priming was not larger than the middle priming, but the attenuation was smaller so that the ground vibration was detected at a longer distance.

• Explosives and Blasting
• /
• v.36 no.3
• /
• pp.19-28
• /
• 2018

Locally damaged structures caused by earthquake or extraordinary external forces have been required to rapidly be dismantled because of its possibility of additional collapses. Particularly, steel frame structures were demolished by the shaped charge blasting method. Recently a research suggested a shape charge blasting technique which uses bent-shaped charge holder of copper plate and emulsion explosive charge to cut thick steel plates. This study simulated the cutting performance of the bent-shaped charge holder with considering types of explosives, thickness of copper liner and stand-off distances using LS-DYNA software. The shape charge blasting test of a 25mm thickness steel plate were used to calibrate the input parameters of the numerical models. The penetration depth and penetration width were analysed with different types of explosives, thickness of copper liner and stand-off distances.

• Explosives and Blasting
• /
• v.26 no.2
• /
• pp.29-37
• /
• 2008

In general, the size of tunnel cross section in construction site is $50{\sim}200m^2$. But, electric cable tunnel, telecommunication cable tunnel, mine tunnel. Waterproof tunnel have small cross section less than $20m^2$. There are so many problem at small sectional tunnel: restriction of equipment, dead pressure by precompression, loss of efficiency, increase of work time. Especially, explosives remainder by precompression of previous detonation is serious problem. To find its measures of dead pressure (explosives remainder), the following series of progress have been conducted: (1) survey of previous study (2) investigate causes of dead pressure (3) set up of its measures (4) application and appraisal at tunnel site. The measures, change of cut pattern, hole space over 40cm, adjustment of delay time, are proved by experimental results.