Large-scale Explosion Research Articles

Damage assessment method of clay brick masonry load-bearing walls under intense explosions with long duration

The vulnerability of clay brick masonry load-bearing (CBML) walls under low-intensity explosions has been extensively investigated. In recent years, large-scale explosions have raised wide concerns about the destructive effect of intense explosions. Intense explosions induced by large TNT equivalent explosives usually cause severe damage to building structures within several kilometers. Although the damage of building structures under intense explosions and normal low-intensity explosions might be different, the differences have yet received any attention in previous studies. Therefore, this study numerically investigates the dynamic performance of CBML walls under intense explosions with long duration (IELD). Firstly, the numerical model is validated by reproducing experimental records. Then the verified model is utilized to investigate the dynamic response and dynamic modes of CBML walls under IELD. Based on the identified failure mechanism, the effects of several parameters such as axial compression ratio, compressive strengths of masonry materials and wall geometry on the damage degrees of CBML walls are analyzed in detail. The damage index based on the residual axial loading capacity of CBML wall is proposed for damage evaluation. The damage assessment method is established for CBML walls under IELD, which can help to evaluate the damage level of clay brick masonry structures under far-field intense explosive scenarios.

Laminated insulated glass units under blast loads: Experimental and numerical study

Laminated insulating glass units (IGUs), commonly used in modern buildings, are prone to shattering from explosive loads, causing significant damage and loss. Existing research on IGUs is constrained by a lack of experimental validation and comprehensive numerical analyses, as large-scale explosion tests are rarely reported due to safety and cost concerns. Furthermore, previous modeling efforts often oversimplify critical factors such as the supporting structure, component interactions, strain rate effects, hourglass energy, and failure criteria, leading to an inadequate representation of glass behavior under explosive loads. This paper addresses these gaps by conducting large-scale explosive test on glass system and utilizing sophisticated nonlinear dynamic analysis with LS-DYNA for simulation. The research considers the influence of the support system and incorporates detailed considerations of component interactions, constitutive relationships, and strain rate effects in the numerical simulations. The results confirm that the proposed model successfully replicates the crack patterns and damage observed in experimental test. Also, it accurately predicts the trajectory, quantity, and size distribution of glass fragments. The proposed modeling approach offers a more informed assessment of damage and improves the evaluation of glass safety in practical applications.

Investigation of the effect of exposed area on blast mitigation response of structures

In this study, the effect of exposed area on the failure response of large plates subjected to large scale explosions are investigated using coupled Eulerian-Lagrangian (CEL) approach. A new failure due to multiple necking between plate center and the clamped edge is reported. The fragment velocity in the plate configuration with square exposed area is higher than the circular exposed area at higher impulses. Further, the square exposed configuration exhibited higher mid-deflection than the circular exposed configuration and this difference increases with the increasing impulse.

Research progress and development trends of hydrogen explosion suppression materials and mechanisms

In order to effectively control and reduce the destructive effects caused by hydrogen leakage and explosion accidents, continuously improving the theoretical system of hydrogen suppression. Based on a survey of literature, this article reviews and discusses the current research status of hydrogen explosion characteristics, explosion suppression materials, and explosion suppression mechanisms. In terms of research on hydrogen explosion characteristics, the impact of initial conditions on macroscopic parameters such as explosion limit, explosion pressure and flame propagation speed were mainly studied. In terms of research on hydrogen suppression, summarizes the research progress of hydrogen explosion suppression materials in recent years from five aspects: inert gas, water mist, solid powder, halogenated hydrocarbons and composite suppression. The suppression effects and suppression mechanisms of different materials were comparatively analyzed. The analysis found that the explosion suppression mechanism of inert gas is mainly physical inerting, and a higher concentration of inert gas is required to completely suppress hydrogen explosion. The explosion suppression mechanism of fine water mist is mainly evaporation and heat absorption, but it cannot completely suppress lean fuel hydrogen explosion. Solid powder materials have almost no inhibitory effect on hydrogen explosion. The explosion suppression mechanism of halogenated hydrocarbons is mainly to eliminate H radicals, but halogenated hydrocarbons have an promoting effect on lean fuel hydrogen. The suppression effect of composite explosion suppressants is better than that of a single explosion suppressor. However, there are currently few studies on the suppression of hydrogen explosions by composite suppressants, and the mechanism of explosion needs to be improved. The article proposes that hydrogen absorption materials, eliminate H radical targeted suppression materials and composite explosion suppression materials are the focus of research on hydrogen suppression materials. Using advanced optical diagnostic technology to study the concentration of radicals and explosion flow field characteristics, and using kinetic simulation software to reveal the complex chain reaction process are important means to study the mechanism of hydrogen explosion suppression. Large-scale explosion suppression experiments are more instructive for engineering applications, but there is a lack of large-scale equipment and experimental research.

FORMATION OF THE NEAR-FAULT DAMAGE ZONE DURING DYNAMIC RUPTURE IN A CRYSTALLINE ROCK MASS

Many models for analyzing the dynamic propagation of seismogenic ruptures are based on solving classical problems of fracture mechanics. It is assumed that the fault is a shear fracture mode with uniformly distributed friction and stresses at the crack tip. Known fracture mechanics theories do not describe the formation of laterally oriented damage zones, i.e., in the direction perpendicular to the crack plane. Observational data indicate the presence of a fairly extensive zone of damaged material in the vicinity of the fault. This is the zone of dynamic influence where the material has an increased number of fractures, higher permeability and lower elastic wave velocities. A correct assessment of the properties and sizes of zones of dynamic influence is crucial for constructing adequate earthquake preparation models. This paper analyzes the development patterns and quantitative characteristics of the damage zone during dynamic earthquake rupture and quasi-static evolution of the fault. To estimate the size and mechanical characteristics of the near-fault damage zone caused by movement along the slip surface, it is convenient to use the value of the second invariant of the deviatoric stress tensor (shear intensity). Matching of the calculated value with one or another degree of rock mass damage can be done using measurement data from large-scale explosions, by comparing them with the calculation results. It is shown that coseismic movement along the fault leads to insignificant changes in the properties of the host rock mass. Although the longitudinal wave velocity near the fault decreases markedly by 30-35%, the permeability increases only by approximately a factor of three, and the increase in the degree of fracturing is almost unnoticeable. This means that the properties of the rock mass change due to the opening of preexisting cracks. Repeated movements do not radically change the characteristic dimensions and properties of the damage zone. It is concluded that the fault-affected zone is formed mainly at the quasi-static stage of the formation of a single main fault zone through the coalescence of individual macrofractures, and future seismogenic movements add to the already existing amount of fractures.

Interaction Behaviors of Longitudinal and Transverse Seismic Waves with Underground Geoengineering Objects

Abstract Main pipelines as long linear objects are vulnerable to dangerous natural and man-made influences. One of the technogenic sources is large-scale explosions, which cause a sharp fluctuations of soil and cause serious damage to underground pipelines. When calculating the strength of pipeline systems, it is assumed that the damage occurs mainly due to additional axial stretching. However, the destruction and damage of pipelines can occur during seismic impacts directed perpendicular to the longitudinal axis of the pipeline. To assess the impact of longitudinal and transverse waves on the underground pipeline during seismic action a software-calculation module is developed. It implements a model of dynamic strength analysis, which allows estimating the magnitude of longitudinal and trans-verse seismic loads on the underground pipeline to establish safe parameters of seismic loads and geometric dimensions of the protected object. The final system of equations of motion of N nodes of a discrete system for a single length of the pipeline is presented as a system of 4N equations of the first order. The efforts on the internal nodes are determined by the strain stresses at the displacement of the nodes of the adjacent rods. The efforts on the nodes of the pipe contour are the diffraction interaction of seismic waves in the soil with the pipe. The system of equations is supplemented by the corresponding initial and boundary conditions. The dependences of the inflow of longitudinal and transverse pressure of explosive seismic pressure on the pipeline are established. The dependences of stresses in the pipeline of the diameter, thickness and type of soil are researched.

An investigation of the effects of the vehicle terror suicide attack in the urban area

In this study, the explosion that occurred due to a suicide attack in Elazig Province in Turkey in 2016 was investigated. For this purpose, a preliminary visual numerical analysis was conducted to form a three-dimensional topographic map, and the damage levels to which the buildings were subjected were estimated. Accordingly, in the aftermath of the explosion, a crater pit formed was formed, in addition to collapsed walls of buildings in the region. The explosion pressure also resulted in broken doors, windows along with their frames, broken glasses, and collapsed roofs. According to the results of the study, the amount of TNT, which was the main explosive in the attack, was calculated based on the level of damage caused by the explosion in the failures analysis. Finally, the amount of TNT that was calculated, and the levels of actual damages in the buildings, which were calculated by choosing a specific area in the region of the attack, were compared. The fact that the region where the attack occurred has a sloping topography and is full of trees at 1000 m altitude is a unique and authentic feature of this study in terms of theoretical and numerical analyses on the subject. Accordingly, it was determined that negative pressure could cause greater damage than positive pressure in large-scale explosions.

Infrasound propagation with realistic terrain and atmospheres using a finite-difference time-domain method

Numerous infrasound observations and complementary numerical simulations have shown that infrasound propagation is strongly influenced by terrain within approximately 10 km from the source. Recent computational efforts using ray theory have shown that terrain influence extends over hundreds of km and is especially strong for waves ducted in the troposphere. Wind and temperature gradients also have a strong influence on propagation at these distances, which suggests that both terrain and atmospheric structure need to be accounted for in waveform modeling at a wide range of distances. Here we show preliminary results from numerical simulations of linear acoustic propagationthrough a moving, inhomogeneous atmosphere using a finite-difference time domain propagation code. We compare our synthetic waveforms in two and three dimensions with existing community infrasound propagation codes and discuss future developments, including open source licensing. Finally, we present preliminary comparisons between modeling and observations from a large-scale explosion at the Utah Testing and Training Range. This scenario highlights the importance of using full-wave modeling compared to ray methods to explain the observed waveforms. [Work funded by the Defense Threat Reduction Agency. Cleared for release.]

The instability of laminar methane/hydrogen/air flames: Correlation between small and large-scale explosions

Darrieus–Landau (D-L) instability can cause significant acceleration in freely expanding spherical flames, which can lead to accidental large-scale gas explosions. To evaluate the potential of using high-pressure lab-scale experiments to predict the onset of cellular instabilities in large-scale atmospheric explosions, experimental measurements of the cellular instabilities for hydrogen and methane mixtures are conducted, in laboratory spherical explosions at elevated pressures. These measurements are compared with those from several large-scale atmospheric experiments. Comprehensive correlations of the pressure effect on a critical Karlovitz number, Kcl, together with those of strain rate Markstein number, Masr, are developed for hydrogen/air mixtures. The regime of stability reduces for all mixtures, as Masr becomes negative. Values derived from large-scale experiments closely follow the same correlation of Kcl with Masr. As a result, the extent of the regime where the laminar explosion flames become unstable can be predicted as a function of Masr and pressure.

Experimental and Numerical Study on the Influence of Plastic-Modified Concrete as Attenuation Layer on Explosion Effect

Reducing the damage of structures under stress wave is one of the popular and challenging issues in the field of protection engineering. In this study, the effect of plastic modified concrete as an attenuation layer on stress wave was investigated through large-scale explosion tests. The volume ratios of plastic particles used as replacement material were 2%, 4%, and 8%. Two explosions were used in each group to analyze the change of pressure under the plastic modified concrete as the attenuation layer. Experimental results showed that as low-impedance material, plastic particles can reduce the stress wave transmitted through the plastic modified concrete, and the elastic–plastic deformation of plastic increases energy consumption. Plastic modified concrete is more difficult to be compacted than loess attenuation layer. Thus, the clipping performance of the plastic modified concrete under the second explosion is better than that of the loess attenuation layer. The effect of plastic modified concrete on shortening the action time of stress wave is not obvious. Plastic modified concrete reduces damage by weakening the peak value of stress wave. The effects of explosive quantity, detonation distance, and plastic particle content on stress wave were studied through experiments and simulation. The propagation process of waves in the plastic modified concrete was studied via numerical simulation, and a fitting formula of wave cutting performance of plastic modified concrete was presented.

Space Radiation of Solar Storm: A Meeting Report in Taiwan

Solar storm was an effect when Sun was active. Solar flares flame released a large amount of energy and caused a large-scale explosion. A large amount of coronal matter was ejected into space by plasma composed of electrons and protons. Their shock waves or magnetic clouds and the earth Magnetic storms generated by the interaction of magnetic fields caused disturbances and squeezing of the earth’s magnetosphere. A solar flare was a phenomenon of solar storm. It had huge eruptions of electromagnetic radiation. The sudden electromagnetic energy traveled with the speed of light. Large solar flare might affect the effects of reliability of electronic components in satellites and could cause economic losses by soft error and could affect human health through the space radiation, especially causing cancer.

Assessing the influence of real releases on explosions: Selected results from large-scale experiments

The research activities in the project Assessing the Influence of Real Releases on Explosions (AIRRE) included a unique series of large-scale explosion experiments with high-momentum jet releases directed into congested geometries with subsequent ignition. The primary objective for the AIRRE project was to gain improved understanding of the effect that realistic releases and turbulent flow conditions have on the consequences of accidental gas explosions in the petroleum industry. A secondary objective was to develop a methodology that can facilitate safe and optimal design of process facilities. This paper presents selected results from experiments involving ignition of a highly turbulent gas cloud, generated by a large-scale, pressurised release of natural gas. The paper gives an overview of the effect on maximum explosion overpressures of varying the ignition position relative to the release point of the jet and a congested region placed inside the flammable cloud, with either a high or a medium level of congestion. For two of the tests, involving a jet release and the medium congestion rig, the maximum overpressures significantly exceeded those obtained in a quiescent reference test. The paper presents detailed results for selected tests and discusses the effect of the initial flow field generated by realistic releases – including turbulence, net flow and concentration gradients – on relevant explosion phenomena.

Прогнозирование скорости колебаний грунтов при массовых взрывах в подземных условиях

At present, to ensure seismic safety in massive explosions, the analytical dependence of the determination of the vibration velocity of M.A. Sadovsky rock mass is mainly used. This dependence is widely used in the creation of seismic-safe technologies for mineral deposits open-pit and underground mining. However, scientific research and production experience showed that the rate of oscillation depends on the energy parameters of the explosive, the diameter and length of its charges, the number of simultaneously exploded charges, the number of deceleration stages, the deceleration interval, etc. The purpose of this article is to predict the speed fluctuations of the massif on the earth surface when conducting the underground explosions depending on the parameters of large-scale explosions and physical-technical properties of the rock masses in the areas of explosion of the protected object. The formulas for calculating the velocity of rock mass on the earth surface during large-scale explosions in the underground conditions are substantiated and presented. The formulas were used for calculating the vibration velocities of the rock mass on the earth surface in accordance with the parameters of drilling and blasting operations during large-scale explosions in the mines of GK VostGOK. Comparison of theoretical (calculated) data and the results of actual measurements indicates their convergence. By changing the controlled parameters in the calculation formulas, it is possible to quantitatively reduce the seismic effect of a large-scale explosions on the protected objects. Further research will be aimed at studying the influence of tectonic faults, artificial contour crevices, filling massif or mined-out space on the rate of seismic-explosive vibrations during blasting operations in the mines. The research results can be used in the preparation of rules for conducting large-scale explosions at the underground mining.

Influence of soil characteristics on working dynamics mining tral authority

The safest way to clear mines and barriers, in terms of saving human life and health, is to clear them at the site. Minesweepers are being used for this purpose, and in recent years they have gained extensive research, which is aimed at the use of large-scale explosion technology. Existing minesweepers in the Armed Forces of Ukraine, as a rule, are old-fashioned, and have certain shortcomings that affect the efficiency of their direct use. These include, first of all, insufficient survivability and different efficiency of their use during demining of minefields with different types of soils: from sandy, loamy and gravel. The range of physical and mechanical properties of the latter is very wide, and therefore - for the operation of an explosive device (mine) requires different amounts of action on the soil surface. The modernized mine trawl neutralizing device in the form of a system of U-shaped rockers with disks at the end is proposed in the work. They, acting directly on the mine, or through a small layer of soil, cause it to explode, provided that the force on the latter is not less than the minimum value required for its disposal. The advantage of this type of mine trawl is that even if one of the working disks fails during the explosion, it is structurally relatively easy to replace it with another. The magnitude of the deepening of the neutralizing disks into the soil (at a constant weight of the mounted part of the trawl), as well as their dynamic action through the soil on the mine depends on the physical and mechanical properties of the soil. Therefore, for the case of, for example, clay or sandy soils during the movement of the trawl, it will be sufficient for the operation of the explosive device, at the same time for the coating of gravel - insufficient. In addition, the amount of deepening of the working disks in the soil depends on its humidity.
 The study of the influence of the main physical and mechanical characteristics of soils on the dynamics of the modernized mine trawl neutralizing device during movement along the minefield (before and after the mine explosion) is the subject of research, hence their relevance.

Numerical study of external explosion characteristics induced by indoor natural gas vented explosion

PurposeThe purpose of this paper is to ascertain the harm to personnel and equipment caused by an external explosion during natural gas explosion venting. The external explosion characteristics induced by the indoor natural gas explosion are the focal points of the investigation.Design/methodology/approachComputational fluid dynamics technology was used to investigate the large-scale explosion venting process of natural gas in a 6 × 3 × 2.5 m room, and the characteristics of external explosion under different scaled vent size (Kv = Av/V2/3, 0.05, 0.08, 0.13, 0.18) were numerically analyzed.FindingsWhen Kv = 0.08, the length and duration of the explosion fireball are 13.39 and 450 ms, respectively, which significantly expands the degree and range of high-temperature hazards. The suitable flow-field structure causes the external explosion overpressure to be more than twice that indoors, i.e. the natural gas explosion venting overpressure may be considerably more hazardous in an outdoor environment than inside a room. A specific range for the Kv can promote the superposition of outdoor rupture waves and explosion shock waves, thereby creating a new overpressure hazard.Originality/valueLittle attention has been devoted to investigating systematically the external explosion hazards. Based on the numerical simulation and the analysis, the external explosion characteristics induced by the indoor large-scale gas explosion were obtained. The research results are theoretically significant for mitigating the effects of external gas explosions on personnel and equipment.

Large-Scale Explosion and Induced Seismicity: Geological, Structural, and Hydrogeological Impacts

This article presents the results of geological, structural, and hydrogeological investigations carried out before and after a large-scale explosion of an object located within the Semipalatinsk Test Site. The obtained data are compared with published information on aftershock emissions registered in an epicentral area after an explosion. Zones with irreversibly changed mechanical and filtrational parameters of geological media are compared with a spatiotemporal distribution of high-amplitude aftershocks in plan and cross-sectional views. The cone of depression formed in the potentiometric surface coincides with the area of registered microseismic events. The general trend of decreasing microseismicity intensity induced by underground large-scale explosion is synchronic with stabilization of the hydrogeodynamic situation.

Development of advanced explosion safety technology for hydrogen systems

A team of researchers from The University of Tokyo, Yamagata University and Hiroshima University, are working to understand phenomena related to large-scale hydrogen gas explosions. The team's research aims to develop a database of gas explosion behaviour through hydrogen gas explosion experiments. The hope is that this will deepen academic understanding, enable the building of a reliable simulation model and, ultimately, develop a practical and advanced explosion safety technology that can be used when designing, developing and implementing hydrogen systems. The findings will lead to improved safety and security for industries implementing hydrogen systems.

Evaluation of the effect of water mist on propane/air mixture deflagration: Large-scale test

Oil and gas explosions threaten the process of industrial protection and personal safety, and explosion risk control/reduction has always been an important issue. As a clean and efficient fire-extinguishing agent, water mist has been evaluated via small-scale tests as a potential efficient material for reducing explosion hazards. To deepen the understanding of large-scale explosion mitigation using actual water mist, which is typically used for fire suppression, a series of experimental tests were conducted using a large explosion vessel (with a 1.5 m × 1.5 m section and a 10 m length). Explosion characteristics—flame propagation process and speed, explosion overpressure, and explosion overpressure rise rate—were determined and analyzed based on the measured data obtained using a Phantom high-speed camera, flame sensors, and pressure sensors, respectively. Two different types of water mist nozzles, different constraints of the vessel and set locations of the nozzles, as well as water mist additives were considered. The results indicated that both the characteristics of the water mist spray and the installation locations of the nozzles have significant effects on the explosion mitigation. In addition, it was found that the K2CO3 additive can double the explosion mitigation effect of water mist using nozzle A, however, this effect is weaker than that when using nozzle B without K2CO3. Therefore, the effect of K2CO3 additive on the explosion mitigation is weaker than of the change in the water mist characteristics. These results will be relevant for further understanding the process safety of explosion mitigation using water mist under large-scale conditions and for the optimum safety design of water mist explosion mitigation systems.

Large-Scale Explosion Propagation Testing of Treated and Non-treated Rock Dust When Overlain by a Thin Layer of Coal Dust

To prevent coal dust explosion propagations, rock dust needs to be lifted and suspended in the air with the coal dust during an explosion. The addition of anti-caking agents prevents caking of rock dust in the presence of water. Mining and rock dusting processes can frequently create alternating layers of rock dust and float coal dust on mine surfaces. For this test series, a thin layer of coal dust was distributed on top of a layer of either treated or non-treated rock dust in the Experimental Mine Barbara, Poland. The experimental results compare the effectiveness of treated and non-treated rock dusts to attenuate a propagating coal dust explosion initiated with either strong or weak methane explosions. Experimental results indicate that the treated rock dust performs better than non-treated rock dust in arresting a propagating explosion, especially in the presence of moisture.

Geomechanical behavior of jointed rock mass in the large-scale blast impact zone

The review of literature sources has allowed determining the mechanism of seismic blasts waves in jointed rock mass. The author presents the theoretical formulas for calculating stresses, relative strains and displacement velocities induced in rock mass by large-scale blasts. The formulas take into account the detonation characteristics of explosives, the borehole diameter, the length of explosive charges, the number of simultaneously blasted charges per groups and the factor of explosion energy redistribution to rock throw. Moreover, the formulas include the properties of rocks between the blasting point and a guarded object, and on the exposed surface of a guarded object. The compressive stresses, relative strains and displacement velocities in rocks are calculated from the formulas. The theoretically found change in the displacement velocity versus distance agrees with the field measurement data obtained in an open pit mine of Polyus company. The formulas of stresses and relative strains were used to define seismic impact exerted by large-scale blasts on the barrier of dry dock No. 1. Based on the calculated results, the recommendations are developed on reduction of seismic impact of blasts during dredging in the dock. The research findings are applicable to developing blasting regulations toward reduction in seismic impact of large-scale explosions on exposed surfaces in rock mass, as well as on the ground surface structures and buildings.