• Journal of the Korean Geosynthetics Society
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• v.21 no.2
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• pp.57-65
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• 2022

This study simulated the shock wave propagation through the tamping material between explosives and hole wall at blasting works and verified the effect of tamping materials. The Arbitrary Lagrangian-Eulerian(ALE) method was selected to model the mixture of solid (Lagrangian) and fluid (Eulerian). The time series analysis was carried out during blasting process time. Explosives and tamping materials (air or water) were modeled with finite element mesh and the hole wall was assumed as a rigid body that can determine the propagation velocity and shock force hitting the hole wall from starting point (explosives). The numerical simulation results show that the propagation velocity and shock force in case of water were larger than those in case of air. In addition, the real site at blasting work was modeled and simulated. The rock was treated as elasto-plastic material. The results demonstrate that the instantaneous shock force was larger and the demolished block size was smaller in water than in air. On the contrary, the impact in the back side of explosives hole was smaller in water, because considerable amount of shock energy was used to demolish the rock, but the propagation of compression through solid becomes smaller due to the damping effect by rock demolition. Therefore, It can be proven that the water as the tamping media was more profitable than air.

• Explosives and Blasting
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• v.38 no.4
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• pp.46-52
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• 2020

Although anti-washout grouts are used extensively in underwater targets, major constraints continue to be associated with their use. These include poor bonding strength, poor pumpability, and loss of high strength in everyday engineering applications. In this study, based on the literature pertaining to self-compacted, non-dispersive, anti-washout grouts, a review of research trends in anti-washout grouts for underwater construction and sealing of karst cavities was carried out in order to determine the problems faced in this field. Grouts used under water suffer a loss of strength and bonding strength in comparison to grouts cast in air. Researchers are designing high-viscosity grouts to overcome the inrush of water and seal karst cavities; however, in doing so, they have inadvertently caused serious problems pertaining to the pumpability of these grouts and concretes in deep target locations. Thus, the majority of the anti-washout grouts and concretes that have been developed are not applicable to deep target environments, instead being suitable for only near-surface targets.

• Explosives and Blasting
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• v.28 no.2
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• pp.59-68
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• 2010

Building demolition and blasting work in urban areas has a possibility which has an effect on the structural stability of nearby structures. In this study, the compressive strength and chemical composition of decrepit concrete materials were estimated by Schmidt rebound test and XRD phase analysis. The damage index of the concrete materials was calculated by measured P-wave velocities. It was revealed that the constituents of the concrete materials affect on the compressive strength. The damage index decreases with increasing compressive strength and decreasing impact energy.

• Explosives and Blasting
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• v.42 no.3
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• pp.9-22
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• 2024

As buildings constructed in the 1980s during a period of rapid urbanization and economic growth have aged, the demand for demolition, especially of reinforced concrete structures, has increased. In large-scale structures such as industrial buildings, a mixed approach utilizing both mechanical demolition and explosive demolition methods is being employed. As the demand for demolition rises, so do safety concerns, making structural stability during demolition a crucial issue. In this study, drones and LiDAR were used to collect actual structural data, which was then used to build a simulation model. The analysis method employed was a combination of the Finite Element Method (FEM) and the Discrete Element Method (DEM), known as the Combined Finite-Discrete Element Method (FDEM), which was used to perform dynamic structural analysis during various demolition phases. The results were compared and analyzed with the commercial software ELS to assess its applicability.

• The Journal of Engineering Geology
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• v.28 no.4
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• pp.701-714
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• 2018

The purpose of this study is to show the possibility of 3-dimensional modeling of open-pit limestone mine by using a rotary-wing unmanned aerial vehicle, a drone, and to estimate the amount of mining before and after mining of limestone by explosive blasting. Analysis of the image duplication of the mine has shown that it is possible to achieve high image quality. Analysis of each axis error at the shooting position after analyzing the distortions through camera calibration was shown the allowable range. As a result of estimating the amount of mining before and after explosive blasting, it was possible to estimate the amount of mining of a wide range quickly and accurately in a relatively short time. In conclusion, it is considered that the drone of a rotary-wing unmanned aerial vehicle can be usefully used for the monitoring of open-pit limestone mines and the estimation of the amount of mining. Furthermore, it is expected that this method will be utilized for periodic monitoring of construction sites and road slopes as well as open-pit mines in the future.

• Explosives and Blasting
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• v.40 no.4
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• pp.15-26
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• 2022

With the recent increase in old and dangerous buildings, the demand for technology in the field of structure demolition is rapidly increasing. In particular, in the case of structures with severe deformation of damage, there is a risk of deterioration in stability and disaster due to changes in the load distribution characteristics in the structure, so rapid structure demolition technology that can be efficiently dismantled in a short period of time is drawing attention. However, structural deformation such as unauthorized extension or illegal remodeling occurs frequently in many old structures, which is not reflected in structural information such as building drawings, and acts as an obstacle in the demolition design process. In this study, as an effective way to overcome the discrepancy between the structural information of old structures and the actual structure, access to actual structures through 3D modeling was considered. 3D point cloud data inside and outside the building were obtained through LiDAR and drone photography for buildings scheduled to be blasting demolition, and precision matching between the two spatial data groups was performed using an open-source based spatial information construction system. The 3D structure model was completed by importing point cloud data matched with 3D modeling software to create structural drawings for each layer and forming each member along the structure slab, pillar, beam, and ceiling boundary. In addition, the modeling technique proposed in this study was verified by comparing it with the actual measurement value for selected structure member.

• Explosives and Blasting
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• v.34 no.1
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• pp.1-10
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• 2016

On August 12, 2015, two huge explosions were accidently happened in Tianjin port, China. The explosion energies of the two explosions were similar to those of TNT 3 tons and TNT 21 tons. Until now, the cause of the explosions was not clearly announced but some guesses of the cause were released. One of the possible cause of the explosion is the generation of explosive acetylene gas from the chemical reaction between $CaC_2$ and spraying water to extinguish fire happened at the storage site of different chemical compounds. The explosion of acetylene gas might ignite the explosion of 800 tons of ammonium nitrate. In this study, the explosion due to the scenario was analyzed in order to check that such a chemical reaction can produce the huge explosion observed at the Tianjin accident.

• Explosives and Blasting
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• v.40 no.1
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• pp.17-28
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• 2022

Electrical pulse disintegration(ED) is known as an efficient technology for recovering valuable resources by inducing dielectric breakdown in solids to separate mineral interfaces in ores among the crushing technologies by high voltage discharge. In this study, ED crushing experiment and mechanical crushing experiment of sulfide minerals were performed, and SEM analysis and Microfocus X-Ray CT of the crushed product were performed in order to analyze the disintegration characteristics of zinc minerals exist in the sulfide minerals by the shock wave generated in the solid by high voltage discharge.

• Proceedings of the KSEE Conference
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• 2008.10a
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• pp.119-127
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• 2008

불꽃놀이는 한국명 연화(煙火), 중국명 폭죽(爆竹), 일본명 하나비(花火), 영어명 파이어웍스 디스플레이(Fireworks display) 표기되며 화약류를 연소 폭발시켜서 빛, 소리, 형태, 연기, 연막, 시간지연, 운동에너지 등을 조합하여 예술적인 감각을 연출시키는 공학으로써 공예술학으로 불랴는 일종의 예술작품이다. 우리나라의 연화기술은 세계적이다. 1980년대에 개발이 완료되었고, 1990년대에 완숙단계흘 거쳐 향후 2010년 이후에는 환경안전을 고려한 최첨단 나노 생명공학으로 발전하여야 할 것이다. 즐거운 불꽃축제 후에 환경오염방지 대책과 비상체제 운영능력, 저장소관리, 불발탄 및 폐기물처리, 시민의식 향상 등이 더욱 요망된다. 본 논문은 올해 제4회를 맞는 부산불꽃축제를 중심으로 현황 및 발전방향과 개선안을 제시하였다.

• Explosives and Blasting
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• v.26 no.1
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• pp.15-21
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• 2008

In case of estimating the shocking vibration during the blasting demolitions, the weight and falling height of the structure, that is a potential energy, had been considered. But, this study presented a new equation which used the impulse concerning a falling weight instead of potential energy as a method of predicting the shock vibration. In this experiment, the data of the impulse were compared with the data of the potential energy by performing the free-fall, and all data were comparatively analyzed by the regression analysis method. Also, the method of the superposition theory, which is calculated by the diminution ratio according to distance, the free-fall difference according to height, and the time giving the shock to the ground according to the breakdown pattern, was compared with the previous vibration data occurring from the blasting demolitions in the same conditions. As a result, this study suggests that the impulse and the method of superposition theory be applied as a method of predicting the shocking vibration. Therefore, these results could be expected to estimate the shocking vibration more accurately than the previous method.