• Proceedings of the Korean Institute of Industrial Safety Conference
• /
• 2002.11a
• /
• pp.172-177
• /
• 2002

가스폭발 시 폭발 압력에 의해 건물의 일부 또는 전체적인 파괴와 함께 외부에 영향을 미치는 영향은 주로 폭풍파의 압력과 고온의 화염이다. 그 중에서도 폭풍압은 건물에서의 가스폭발 시 파열면을 통과한 급격한 압력 방출에 의해 생겨나는 물리적인 현상으로 그 충격은 때에 따라서 구조물을 붕괴시킬 만큼 크다. 폭발에 의해 발생되는 폭풍압에 의한 피해가 크기 때문에 과거부터 폭풍압에 대한 연구가 계속되어 왔다.(중략)

• Explosives and Blasting
• /
• v.41 no.3
• /
• pp.1-12
• /
• 2023

A basic assessment of techniques to mitigate the risk of blast shock waves from proximity explosions was conducted. Common existing techniques include using mitigant materials to form barriers around the explosive or in the direction of propagation of the shock wave. Various explosive energy dissipation mechanisms have been proposed, and research on blast shock wave mitigation utilizing impedance differences has drawn considerable interest. In this study, shear thickening fluid (STF) was applied as a blast mitigation material to evaluate the effectiveness of STF mitigation material on explosion shock wave mitigation through explosion experiments and numerical analysis. As a result, the effectiveness of the STF mitigant material in reducing the explosion shock pressure was verified.

• Journal of the Korean Society for Railway
• /
• v.17 no.2
• /
• pp.100-105
• /
• 2014

To design a submerged floating railway that is safe against underwater explosions, railway behavior must be investigated and clarified. In this paper, shock waves and impulse pressures generated by a charge away from the submerged floating railway are expressed using experimental formulas. The submerged floating railway tethered by mooring lines is modeled as a simply supported beam with elastic springs. Finite element analysis for the beam model subjected to impulse loading is conducted so that the response of the submerged floating railway can be investigated. For design purposes, a simplified analysis method combined with dynamic load factor is proposed for the same model. Maximum deformation and internal forces are calculated and compared with the time dependent analysis results. It is shown that the simplified analysis results show good agreement.

• Tunnel and Underground Space
• /
• v.22 no.1
• /
• pp.69-76
• /
• 2012

Theoretical backgrounds on the experimental methods of explosive welding, explosive forming and shock consolidation of powders are introduced. Explosive welding experiments of titanium (Ti) and stainless steel (SUS 304) plate were carried out. It was revealed that a series of waves of metal jet are generated in the contact surface between both materials; and that the optimal collision velocity and collision angle is about 2,100~2,800 m/s and $15{\sim}20^{\circ}$, respectively. Also, explosive forming experiments of Al plate were performed and compared to a conventional press forming method. The results confirmed that the shock-loaded Al plate has a larger curvature deformation than those made using conventional press forming. For shock consolidation of powders, the propagation behaviors of a detonation wave and underwater shock wave generated by explosion of an explosive are investigated by means of numerical calculation. The results revealed that the generation and convergence of reflected waves occur at the wall and center position of water column, and also the peak pressure of the converged reflected waves was 20 GPa which exceeds the detonation pressure. As results from the consolidation experiments of metal/ceramic powders ($Fe_{11.2}La_2O_3Co_{0.7}Si_{1.1}$), shock-consolidated $Fe_{11.2}La_2O_3Co_{0.7}Si_{1.1}$ bulk without cracks was successfully obtained by adapting the suggested water container and strong bonding between powder particles was confirmed through microscopic observations.

• Proceedings of the KSEE Conference
• /
• 2006.10a
• /
• pp.119-140
• /
• 2006

The rock excavation work by doing blasting breaks the rock by using a shock pressure and gas pressure produced when explosive explodes and the shock wave by shock pressure propagated three-dimensionally from the exploding center is on the decrease notably to the distance, however, $0.5{\sim}20%$ of energy produced by blasting propagates into the ground outside a crack zone by the shape of an elastic wave, on the ground it appears as a ground vibration with a seismic amplitude and a seismic cycle, it is called a blasting vibration. on the other side, what propagated in the air is called a blasting sound. The blasting sound of both means the things which the shock sound within the range the audible frequency($20{\sim}20000Hz$) of the elastic wave in the air influences the response system of a human body, it doesn't harm physically to any structures but influences unreasonably a work accomplishment, such as a work discontinuance due to the outbreak of a public complaint by a mental pain, reduction of a blasting scale, etc.. So, this study is examined at about 20 sites on the installation time and method of soundproofing facilities for reduction of the sound accompanied with a tunnel blasting work.

• Explosives and Blasting
• /
• v.27 no.1
• /
• pp.1-6
• /
• 2009

The strainer can be clogged by dusts in a well. As a result, the permeability of a strainer is extremely reduced. This paper is intended to propose a cleaning method of strainer using blasting pressure of the detonating cords and to examine the applicability of this method. The pressure range that was not expected to affect the strainer was estimated. Test results of $3,000\;kg/cm^2$ pressure with a diameter of 12 cm without damage to the strainer was found to be appropriate. The mortar attached to the strainer was almost completely eliminated.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.20 no.3
• /
• pp.825-831
• /
• 1996

Using the two-dimensional hydrocode HI-DYNA2D, a calculation on the explosive selding of dissimilar plates(Steel Titanium) was made for the pressure, temperature, velocity and impact ingles adjacent to the collision point during the welding process. The FEM result indicates that optimal stand-off distance of initially parallel set-up is 3-5mm for various values of the explosive thickness. The calculation shows that when the explosive thickness is around 30mm, the temperature of welding point which is strongly related to the metallic jet formation is 2, 000-3, 500K for the given stand-off distance.

• Tunnel and Underground Space
• /
• v.21 no.4
• /
• pp.320-327
• /
• 2011

In this study, for stemming effect in blast of the mortar block body, the crushed granite sand as fine aggregate, which is waste rock obtained at the ○○ limestone mine, was investigated to compare with stemming materials such as sea sand, river sand, clayed soil and water can be acquired easily at the field. The mortar block body was manufactured with the dimensions of 50 cm width, 50 cm length and 70 cm height. The direct shear and sieve separator test were performed, and the properties of friction resistance were analyzed by the extrusion test for five stemming materials. Axial strain of steel bar and ejection velocity of stemming materials due to the explosive shock pressure in blasthole with the stemming length of 10 cm and 20 cm in the mortar blast test were measured by the dynamic data acquisition system. Among stemming materials, axial strain showed the largest value at the crushed granite sand as fine aggregate, and the ejection velocity was the smallest value at the stemming of water. The results has shown correlate with harden unit weight in blasthole, particle size distribution, shear resistance, and extrusion strength of stemming materials. The ejection velocity of stemming material at the mouth of blasthole and the axial strain of steel bar in the inside of blasthole tend to be inversely proportional to each other, represent exponentially.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.29 no.6
• /
• pp.521-527
• /
• 2016

This paper is concerned with the numerical analysis of dynamic response of floating offshore wind turbine subject to underwater explosion using an effective non-reflecting technique. An infinite sea water domain was truncated into a finite domain, and the non-reflecting technique called the perfectly matched layer(PML) was applied to the boundary of truncated finite domain to absorb the inherent reflection of out-going impact wave at the boundary. The generalized transport equations that govern the inviscid compressible water flow was split into three PML equations by introducing the direction-wise absorption coefficients and state variables. The fluid-structure interaction problem that is composed of the wind turbine and the sea water flow was solved by the iterative coupled Eulerian FVM and Largangian FEM. And, the explosion-induced hydrodynamic pressure was calculated by JWL(Jones-Wilkins-Lee) equation of state. Through the numerical experiment, the hydrodynamic pressure and the structural dynamic response were investigated. It has been confirmed that the case using PML technique provides more reliable numerical results than the case without using PML technique.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.27 no.4
• /
• pp.281-288
• /
• 2014

As a gas explosion is the most fatal accident in shipbuilding and offshore plant industries, all safety critical elements on the topside of offshore platforms should retain their integrity against blast pressure. Even though many efforts have been devoted to develop blast-resistant design methods in the offshore engineering field, there still remain several issues needed to be carefully investigated. From a procedure for calculation of explosion design pressure, impulse of a design pressure model having completely positive side only is determined by the absolute area of each obtained transient pressure response through the CFD analysis. The negative pressure phase in a general gas explosion, however, is often quite considerable unlike gaseous detonation or TNT explosion. The main objective of this study is to thoroughly examine the effect of the negative pressure phase on structural behavior. A blast wall for specific FPSO topside is selected to analyze structural response under the blast pressure. Because the blast wall is considered an essential structure for blast-resistant design. Pressure time history data were obtained by explosion simulations using FLACS, and the nonlinear transient finite element analyses were performed using LS-DYNA.