• Explosives and Blasting
• /
• v.40 no.3
• /
• pp.54-65
• /
• 2022

Recently, the demand for the dismantling of large-scale industrial structures is increasing, and the construction of restoring the dismantled industrial to their original natural environment is underway. This case was an application of the explosive demolition method to the demolition of a large section turbine foundation structure which structural obsolescence and failure to meet functional requirements. As a result of the explosive demolition, the fracture condition of the turbine foundation was satisfactory, and the explosive demolition was completed without causing any damage to the surrounding facilities.

• Explosives and Blasting
• /
• v.36 no.2
• /
• pp.10-18
• /
• 2018

The shaped charge is used in explosive demolition of steel frame structure, but it was often not used because it was limited to use or impossible to supply at domestic and foreign. To solve this problem, we needed a device that could generate matal jets using industrial explosive. In this study, we made a charging container, which metal jets were generated when explosives were detonated. Cutting performance tests were carried out to evaluate the effect of cutting of a charging container on a steel plate of 25mm thickness. In addition, we compared the results between the numerical simulation of penetration process and cutting performance tests and then was evaluated a cutting performance for steel plates of 35mm and 70mm thickness.

• Explosives and Blasting
• /
• v.38 no.2
• /
• pp.13-21
• /
• 2020

The shaped charge was used in explosive demolition of a steel frame structure, but it was often not used because it was limited to use and impossible to supply at domestic and overseas. Existing linear shaped charge did not have sufficient cutting performance to cut steel frame structures with a huge scale and thick steel plate. To solve these problems, we produced a device that could generate metal jets using industrial explosives of high detonation velocity and pressure. In this study, we made a charging container of three types which applicable to explosive demolition of steel frame structures. The experiment of cutting performances was carried out to evaluate the effect of cutting of charging containers on the various thicknesses of the H-beam and steel plate. As a result of the experiment, sufficient cutting performance was confirmed.

• Explosives and Blasting
• /
• v.39 no.1
• /
• pp.1-9
• /
• 2021

As the national economic growth and the rapid increase in industrial structures are aging, the demand for removing steel structures is increasing, and research on improving the penetration performance of the linear shape charge explosives. In the study, numerical analyses were performed on the effect of the type of explosive used in the self-made shape charging container and the initiation method on the cutting performance of the steel plate and the effect on the shaped explosive installed close to it. ANSYS LS-DYNA, which can analyze the large deformation problem of materials due to explosion, was used, and an ALE(Arbitrary-Lagrange-Eulerian) model was applied that enables interlocking analysis of gases, liquids, and solid.

• Explosives and Blasting
• /
• v.34 no.1
• /
• pp.19-28
• /
• 2016

The number of industrial structures that must be demolished due to functional and structural deterioration has been increased. There is an increasing application of explosive demolition or explosive demolition combined with mechanical demolition to minimize temporal and spatial environmental hazardous factors created during the process of demolition. In this case study, to demolish the turbine foundation structure, which is a large-section reinforced concrete structure, the parital explosive demolition thchnique was conducted. As a result of the partial explosive demolition, the overall crushing of the blasting sections of beam-column joints structure with haunched beams and second-floor columns about the turbine foundation was satifactory, and the explosive demolition was completed without causing any damage to surrounding facilities.

• Explosives and Blasting
• /
• v.40 no.3
• /
• pp.66-76
• /
• 2022

Recently, the demand for the dismantling of old industrial complexes has been increasing, and the construction of restoring the dismantled industries to their original natural environment is underway. In this case, the felling method was applied to the explosive demolition method to dismantle a large steel frame structure in an old industrial complex. We used a charging container to cut the steel frame structure that generates a metal jet. The thickness of the thick steel structure in the blasting section was controlled by gouging which a method of digging deep groove by gas and oxygen flame or arc thermal. As a result of the explosive demolition, the steel frame structure collapsed precisely according to the estimated direction. The explosive demolition was completed without causing any damage to the surrounding facilities.

• Applied Chemistry for Engineering
• /
• v.33 no.3
• /
• pp.302-308
• /
• 2022

The PdO nanoparticle with large surface area was selected to solve the environmental pollution problem at fire range caused by high energy explosives research department explosive (RDX) and high melting explosive (HMX). By simulating water pollution, RDX and HMX nitramine explosives were dissolved in water, followed by the degradation reaction at 313 K by adding PdO. In order to measure the degradation reaction rate of explosives, ¹H NMR was used, which can monitor the reaction rate without losing sample during reaction, and observe the progress of the reaction through the spectrum. The results showed that the degradation of RDX and HMX by PdO nanoparticles are pseudo-first order reaction. The degradation of explosives compounds were observed via the chemical shift and peak intensity analysis of NMR peaks. The measured rate constants for these reactions of RDX and HMX were 2.10 × 10^-2 and 6.35 × 10^-4 h^-1, respectively. This study showed that the application of PdO nanoparticles for explosives degradation is a feasible option.

• Applied Chemistry for Engineering
• /
• v.20 no.2
• /
• pp.159-164
• /
• 2009

Monomers of oxetane high explosives were theoretically examined in terms of reactivity, reaction mechanism and process of polymerization substituted by azido $(-CH_2N_3)$, nitrato $(-CH_2ONO_2)$ and hydrazino $(-CH_2N_2H_3)$ which belong to the 5th class hazardous materials and have explosiveness under acid catalyst using MINDO/3, MNDO, and AMI methods for formal charge, heat of formation, and energy level. Nucleophilicity and base of oxetane high explosives could be explained by negative charge size of oxetane oxygen atom and reactivity of oxetane in the growth stage of polymerization under acid catalyzer could be expected to be governed by positive charge size of axial carbon atom and low LUMO energy of electrophile. It could be estimated that carbenium ion was more beneficial in the conversion process of oxetane high explosives than that of stabilization energy (13.90~31.02 kcal/mole) of oxonium ion. In addition, concentration of oxonium ion and carbenium ion in equilibrium state influenced mechanism and it was also estimated that $S_N1$ mechanism reacts faster than that of $S_N2$ in prepolymer growth stage considering quick equilibrium based on form and calculation of polymerization under acid catalyzer.

• Explosives and Blasting
• /
• v.40 no.4
• /
• pp.35-46
• /
• 2022

While the construction of dismantling the old industrial complex and restoring the dismantled industrial site to its original natural environment the is underway. In this paper, we introduce a case of dismantling a turbine building which one of the a large steel frame structures in an old industrial complex by applying the progressive collapse method among the blasting demolition methods. We used a charge container that generates a metal jet to cut dismantling the turbine building. The thickness of the steel structure was adjusted to 30 mm or less by applying gouging, which was a method of digging deep grooves by gas and oxygen flames or arc thermal, in the part where the cutting thickness was thick in the blasting section. The total amount of charge used for the blasting of turbine building was 175 kg, 165 electronic detonators and 124 charge containers. As a result of the blasting demolition, the turbine building was collapsed precisely according to the estimated direction. The blasting demolition was completed without causing any damage to the surrounding facilities.

• Applied Chemistry for Engineering
• /
• v.30 no.2
• /
• pp.178-185
• /
• 2019

Three spherical quaternary composites composed of metal/metal oxide/high explosive/oxidizer were prepared by a crystallization/agglomeration process. From the characteristics of composites by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), the shortening of the decomposition zone of high explosives in the quaternary composite was observed, which may be attributed to the autocatalytic reaction caused by $ClO_2$ or HCl which are ammonium perchlorate (AP) degradation products. The activation energy analysis showed that the activation energy abruptly decreases at the end of the decomposition zone of high explosives, and it was considered to be caused by $HNO_2$ which is common in decomposition products of high explosives. The activation energy predicted from complex pyrolysis results by the distributed activation energy model (DAEM) showed much better in accuracy than those by model-fitting methods such as Kissinger-Akahira-Sunose and Flynn-Wall-Ozawa models.