Search

A critical challenge of any blast simulation facility is in producing the widest possible pressure-impulse range for matching against equivalent high-explosive events. Shock tubes and blast simulators are often constrained with the lack of effective ways to control blast wave profiles and as a result have a limited performance range. Some wave shaping techniques employed in some facilities are reviewed but often necessitate extensive geometric modifications, inadvertently cause flow anomalies, and/or are only applicable under very specific configurations. This paper investigates controlled venting as an expedient way for waveforms to be tuned without requiring extensive modifications to the driver or existing geometry and could be widely applied by existing and future blast simulation and shock tube facilities. The use of controlled venting is demonstrated experimentally using the Advanced Blast Simulator (shock tube) at the Australian National Facility of Physical Blast Simulation and via numerical flow simulations with Computational Fluid Dynamics. Controlled venting is determined as an effective method for mitigating the impact of re-reflected waves within the blast simulator. This control method also allows for the adjustment of parameters such as tuning the peak overpressure, the positive phase duration, and modifying the magnitude of the negative phase and the secondary shock of the blast waves. This paper is concluded with an illustration of the potential expanded performance range of the Australian blast simulation facility when controlled venting for blast waveform tailoring as presented in this paper is applied. [ABSTRACT FROM AUTHOR]

With the application of electronic detonators, delayed blasting is considered a very effective method to improve rock fragmentation, and this technique is widely used in practical engineering. Therefore, it is necessary to study the rock-breaking mechanism of double-hole delayed blasting. In this paper, based on the finite difference method, the influence of double-hole delayed blasting on the reservoir permeability was quantitatively analyzed by adopting the adjacent hole spacing, delay time, and decoupling coefficient (K) as variables and the permeability increment as an evaluation index. Based on the parameters studied in this paper, it was found that the effect of the delay time on the reservoir permeability depends on the hole spacing. When the hole spacing is less than 20ra (ra is the borehole radius), a reasonable delay time could significantly increase the reservoir permeability, but when the hole spacing is greater than 20ra, the delay time does not affect reservoir permeability enhancement. The decoupling coefficient could control the attenuation speed of shock wave energy. For K = 2, energy attenuation occurred the slowest, and the reservoir permeability increase effect was the best. Based on site-scale numerical simulations, the mechanism of stress superposition between boreholes was revealed, and the position of stress superposition was controlled by adjusting the delay time to break hard reservoir rock so that the cracks between two holes were connected, i.e., accurate reservoir reconstruction was achieved. This work provides a certain guiding basis for actual engineering applications. [ABSTRACT FROM AUTHOR]

This paper investigates the three-dimensional crack propagation and damage evolution process of metallic column shells under internal explosive loading. The calibration of four typical failure parameters for 40CrMnSiB steel was conducted through experiments and subsequently applied to simulations. The numerical simulation results employing the four failure criteria were compared with the differences and similarities observed in freeze-recovery tests and ultra-high-speed tests. This analysis addressed the critical issue of determining failure criteria for the fracture of a metal shell under internal explosive loads. Building upon this foundation, the damage parameter Dc, linked to the cumulative crack density, was defined based on the evolution characteristics of a substantial number of cracks. The relationship between the damage parameter and crack velocity over time was established, and the influence of the internal central pressure on the damage parameter and crack velocity was investigated. Variations in the fracture modes were found under different failure criteria, with the principal strain failure criterion proving to be the most effective for simulating 3D crack propagation in a pure shear fracture mode. Through statistical analysis of the shell penetration fracture radius data, it was determined that the fracture radius remained essentially constant during the crack evolution process and could be considered a constant. The propagation velocity of axial cracks ranged between 5300 m/s and 12600 m/s, surpassing the Rayleigh wave velocity of the shell material and decreasing linearly with time. The increase in shell damage exhibited an initial rapid phase, followed by deceleration, demonstrating accelerated damage during the propagation stage of the blast wave and decelerated damage after the arrival of the rarefaction wave. This study provides an effective approach for investigating crack propagation and damage evolution. The derived crack propagation and damage evolution law serves as a valuable reference for the development of crack velocity theory and the construction of shell damage evolution modes. [ABSTRACT FROM AUTHOR]

Blast deafness and balance disorders are common consequences of modern warfare and terrorist actions. A predictive evaluation system can assist commanders in quickly gathering information on the incapacitation of combat personnel. However, a critical challenge to this goal was to clarify the dose–response relationship between the blast parameters and the severity of auditory and vestibular dysfunction. This paper describes the algorithms for a prediction model. We performed blast experiments to obtain data on animal auditory/vestibular dysfunction under different overpressures. Peak overpressure and positive phase duration of the blast wave were obtained by pressure measurements. The severity of auditory and vestibular dysfunction was established by the auditory brainstem response test, behavioral rating, and vestibular-evoked myogenic potentials tests. Test data were analyzed using receiver operating characteristic (ROC) curves and logistic regression analysis to obtain the overpressure limits for auditory/vestibular function and logistic regression curves for severity separately. The ROC curve analysis showed that the overpressure limit for the auditory function was 32.635 kPa and the vestibular function was 96.275 kPa. Logistic regression fitted curves illustrated the dose–response relationship between the coefficient K, normalized by peak overpressure and positive phase duration, and the risk probability of auditory and vestibular disfunction. The prediction model for the risk of auditory and vestibular disfunction severity (mild/moderate/severe) has been established based on the overpressure limit and dose–response relationship. [ABSTRACT FROM AUTHOR]

The significance of predicting the dynamic response and damage of an existing concrete tunnel during underground blasting has increased owing to the close proximity between the newly built and existing tunnels. Peak particle velocity (PPV) is a commonly used criterion in the assessment of blast-induced structural damage. However, such structural damage is also associated with the frequency content of the blast wave. Nevertheless, the recommended threshold PPVs, which are based on empirical criteria, predict conservative estimations. Using stringent and regulated blasting methods often results in project delays and escalates the total project expenditure. In this paper, a three-dimensional finite element model of an underground tunnel has been developed in LS-DYNA to analyze damage to the concrete tunnels under blast loading. A suite of analyses was performed to examine the potential damage induced in the underground tunnel. A lower frequency load was found to have a greater potential for producing damage compared with a high frequency blast load. The results showed that the location of the cracking within the tunnel, such as the arch foot or tunnel wall, was also influenced by the frequency of the blast wave. The maximum allowable PPV for the concrete tunnel was determined for a range of frequencies based on predicted free field PPV and additional factors of safety of 1.2 and 1.5 were established, depending on the safety needs and importance of the tunnel construction. Thus, our findings provide useful information for improving the evaluation of tunnel damage and guaranteeing the safety of underground tunnels. [ABSTRACT FROM AUTHOR]

With the shift of coal seam mining to the deep, the in-situ stress of coal and rock mass increases gradually. High ground stress can limit the generation of rock cracks caused by blasting, and blasting usually shows different crushing states than low stress conditions. In order to study the blasting expansion rule of rock mass with cavity under high ground stress and the rock mass fracture state under different side stress coefficients. In this paper, the effective range of blasting and the stress distribution under blasting load are analyzed theoretically. The RHT (Riedel-Hiermaier-Thoma) model is used to numerically simulate the blasting process of rock mass with cavity under different ground stress, and the influence of ground stress and lateral pressure coefficient on the crack growth of rock mass is studied. The results show that when there is no ground stress, the damage cracks in rock mass are more concentrated in the horizontal direction and the fracture development tends to the direction where the holes are located, which confirms the guiding effect and stress concentration effect of the holes in rock mass, which helps to promote the crack penetration between the hole and the hole. The length difference of horizontal and vertical damage cracks in rock mass increases with the increase of horizontal and vertical stress difference. Under the same lateral stress coefficient, the larger the horizontal and vertical stress difference is, the stronger the inhibition effect on crack formation is. For blasting of rock mass with high ground stress, the crack formation length between gun holes decreases with the increase of stress level, and the crack extends preferentially in the direction of higher stress. Therefore, the placement of gun holes along the direction of greater stress and the shortening of hole spacing are conducive to the penetration of cracks between gun holes and empty holes. The research can provide reference for rock breaking behavior of deep rock mass blasting. [ABSTRACT FROM AUTHOR]

Featured Application: The shock wave generator developed in this article is easy to operate and reusable. It can generate high-pressure and high-speed shock waves. Therefore, it can be widely used in the design and development of various devices, such as shock-driven power generation devices, pipeline obstruction removal devices, geothermal well productivity enhancement devices, lightweight rock fracture devices for disaster relief, shock wave soil loosening and hole fertilization devices that can reduce soil carbon emissions, etc. Wind energy is a kind of renewable energy with great potential for development. This study mainly investigated the application of shock waves generated by high-pressure gases (wind energy) for generating energy. In this study, we designed a new supersonic shock wave generator that can be reused without disassembling and assembling bolts and developed a shock wave monitoring system. It could measure the velocity of the generated shock waves at about Mach 3–5, and the output pressure exceeded 900 kg/cm2 (more than 100 times the input pressure). Then, we developed a power generation system driven by supersonic shock waves based on the characteristics of the new shock wave generator, which could generate high-pressure and high-speed blast waves and could be reused. The shock wave generator can repeatedly generate high-pressure waves to drive the Tesla turbine and then rotate the magnetic energy generator for power generation. This paper used tank pressure, output pressure, gas flow, rotation speed, voltage, and current detected by the system to conduct power generation performance analysis. When the minimum rotation speed was set to 1500 rpm and three bulbs were turned on as loads, the system could generate an average voltage of 36.64 V and an average current of 211.01 mA as output (power about 7731.41 mW). [ABSTRACT FROM AUTHOR]

In tunnel smooth blasting, optimizing the water interval charging structure of peripheral holes is of great significance in improving the effect of smooth blasting and reducing the unit consumption of explosives. Addressing the issue of a single traditional evaluation standard, this paper proposes a composite index evaluation method for rock blasting damage in different zones, and the best charging structure is optimized according to the evaluation results. Taking Liyue Road Tunnel Light Smooth Blasting Project in Chongqing as the Research Background, the numeric models were established with ten kinds of charge structures, the charge structures and explosive quantity were optimized according to the evaluation results, and then the field tests were conducted. The results show that when the length of the water medium at the bottom of the hole is 20 cm, the damage range of the retained rock mass can be controlled while ensuring rock fragmentation. If the length of the water medium at the orifice and in the center of the hole is more than 30 cm, it will affect the superposition effect of the blast stress wave, resulting in under-excavation; in the preferred charge structure, the ratio of the length of the upper and lower explosives reaches 1:3, and the ratio of the length of the water medium is 2:2:1, which achieves a better rock-breaking effect in the field test. [ABSTRACT FROM AUTHOR]

The ongoing study of blast waves and blast wave mitigation continues to play an essential role in protecting structures and personnel. The methodology, however, for capturing far-field blast waves in large-scale tests has remained largely unchanged for three decades, relying on large arrays of pressure transducers connected by hundreds of meters of cabling and requiring a considerable amount of time to set up. This paper evaluates the use of a modern low-cost microprocessor with high computational power to capture blast waves with sufficient fidelity to provide scientists and engineers with credible data. The system utilizes an ARM Cortex M7 processor as an experimental data acquisition (DAQ) system for measuring far-field blast waves in an open-air blast arena at sampling speeds of up to 1.8 Msps (megasamples per second). The experimental system's performance was evaluated by comparing it to a traditional commercial system used for measuring blast waves. The comparison showed an average Spearman correlation coefficient r of 0.928 between the two systems, suggesting a low variance between the commercial and experimental DAQ systems. This suggests that, despite its simplicity, the experimental system is an effective and low-cost alternative for accurately measuring blast waves. [ABSTRACT FROM AUTHOR]

Damage assessment of the wing under blast wave is essential to the vulnerability reduction design of aircraft. This paper introduces a critical relative distance prediction method of aircraft wing damage based on the back-propagation artificial neural network (BP-ANN), which is trained by finite element simulation results. Moreover, the finite element method (FEM) for wing blast damage simulation has been validated by ground explosion tests and further used for damage mode determination and damage characteristics analysis. The analysis results indicate that the wing is more likely to be damaged when the root is struck from vertical directions than others for a small charge. With the increase of TNT equivalent charge, the main damage mode of the wing gradually changes from the local skin tearing to overall structural deformation and the overpressure threshold of wing damage decreases rapidly. Compared to the FEM-based damage assessment, the BP-ANN-based method can predict the wing damage under a random blast wave with an average relative error of 4.78%. The proposed method and conclusions can be used as a reference for damage assessment under blast wave and low-vulnerability design of aircraft structures. [ABSTRACT FROM AUTHOR]

At present, the drill-and-blast method is still one of the main construction means in the road tunnel excavation process. When the tunnel penetrates underneath sensitive structures such as high-voltage transmission towers, the blasting and supporting parameters must be strictly controlled to ensure the stability and safety of the surface structures. In this paper, numerical simulations based on a large-section shallow buried tunnel project in Zhuhai are conducted to study the effect of controlled tunnel blast on the dynamic response of transmission towers. The numerical simulation results indicate that the blast vibration velocity of the rock generated by controlled blasting decreases rapidly along the tunnel excavation direction. The blast vibration velocity of the high-voltage transmission tower and its pile foundation gradually increases with the propagation of the blast waves, and the maximum vibration velocity is about 1.24 cm/s. The results indicate that the controlled blasting design of this project can effectively restrain the vibration velocity induced by the blasting load and could ensure the stability and safety of the transmission tower. [ABSTRACT FROM AUTHOR]

Vapor cloud explosions (VCEs) continually generate an extreme blast load and cause heavy casualties, property loss, and environmental pollution. It is therefore essential to evaluate and control the consequence of vapor cloud explosions. So far, the widely used models in vapor cloud explosions include the Trinitrotoluene (TNT) equivalency method (TNT EM), the Netherlands Organization for Applied Scientific Research (TNO) multienergy method (TNO MEM), the Baker-Strehlow-Tang (BST) method, and FLACS. In this paper, a review and comparative analysis of vapor cloud explosion models were carried out. Combined with a realistic petrochemical plant with different obstacle blockage ratio, the side-on overpressure and duration were evaluated and analyzed with different vapor cloud explosion models. Based on the predicted blast load, the structural response of RC columns, including nonseismic columns and seismic columns with different cross sections, were studied through computer simulation. Vapor cloud explosion models were compared with each other from the perspective of the structural response. It was found that the selection of vapor cloud explosion models has a great influence on the dynamic response of RC columns; the TNO multienergy method was the most conservative method in all vapor cloud explosion models, but its failure mode was quite different from FLACS in the scenario with a high blocking ratio. The predicted results from the Baker-Strehlow-Tang method were closest to that of FLACS. The structural response of the TNT equivalency method was close to that of the TNO multienergy method with the influence of the blast wave shape in Scenario 1. This work points out the applicable characteristics of each load model, which can provide some suggestions for the blast-load evaluation of vapor cloud explosions in the RC column design. [ABSTRACT FROM AUTHOR]

In this paper we present a Computational Fluid Dynamics (CFD) simulations for the case of natural gas explosion in urban area. Blast simulations aid in the development of effective mitigation strategies. By understanding how blast waves propagate through an urban environment, authorities can implement measures such as barriers, protective shields, strategies for firefighting strategy or evacuation plans to minimize damage and casualties. Accurate simulations provide insights into the potential impact of a blast on surrounding infrastructure and populations. This information is crucial for emergency response planning, helping authorities to allocate resources and respond effectively to minimize the consequences of an explosion. [ABSTRACT FROM AUTHOR]

A multilayer liquid-containing protective structure is composed of a liquid tank, ceramic, a honeycomb sandwich and homogeneous steel. This structure has superior resistance to combined blast wave and fragment loading. Due to the relatively complicated construction of the structure, the inner damage, energy absorption and the protection characteristics of the multilayer liquid-containing protective structure need to be further studied. In this paper, a multilayer liquid-containing structural model is constructed, the dynamic response process of multilayer liquid-containing structure under combined blast wave and fragment loading is analyzed, and the damage and energy absorption characteristics of each layer structure are investigated. In addition, the effects of the charge mass and fragment form on the structural failure modes and energy absorption characteristics are discussed. The results indicate that different modes of damage occur in each layer structure. The front plate of the liquid tank sustains the most damage and absorbs the most energy, and the honeycomb sandwich absorbs the second most energy. The damage area of the front plate and the degree of compression collapse of the honeycomb sandwich increase with increasing charge mass. When the charge mass is small, the damage mode of the multilayer liquid-containing structure is greatly affected by fragments, and the damage effect of the blast wave increases with increasing charge mass. For a constant charge mass, the degree of damage to the protective structure is minimally impacted by the fragment weight, and the degree of damage can be substantially reduced by reducing the number of fragments. [ABSTRACT FROM AUTHOR]

In situ stress and joints have a significant impact on the propagation and attenuation pattern of blast stress waves, and they are two important factors that must be considered for tunnel blasting hole network deployment. This paper proposes a blast stress wave attenuation equation and a peripheral hole distance calculation method under the combined action of in situ stress and joints. First, the static and dynamic parameters of the jointed slate are obtained by drilling core samples in the field and conducting indoor tests. Next, considering the geometric and physical attenuation of the blast stress wave, the attenuation formula of the blast stress wave under the combined action of in situ stress and joints is derived. Based on the theory of the combined action of stress waves and explosive gas, a formula for calculating the peripheral hole distance that integrates the effects of in situ stress, joints, and tensile strength of the rock body is proposed. Finally, LS-PREPOST software is used to analyze the damage to the surrounding rock, verified by an on-site blasting test. The results show that the blast stress wave attenuation formula proposed in this paper can accurately predict the stress wave peak value under the combined action of in situ stress and joints. Combining the geological conditions and blasting parameters of the Bayueshan Tunnel study section, the optimal peripheral hole spacing is calculated to be 45 cm. The average over-excavation value of the grade IV surrounding rock is controlled within 22 cm and the over-consumption of concrete per linear meter is controlled within 100% using the peripheral hole layout method and the hole network layout parameters proposed in this paper. The research results provide a reference for the control of over-excavation and under-excavation in large-section tunnel blasting. [ABSTRACT FROM AUTHOR]

This paper studies the response characteristics of shock wave and boundary layer interaction (SWBLI) controlled by high-frequency pulsed arc discharge (PAD) in a Mach 2.5 flow. The dynamic evolution of SWBLI disturbed by arc plasma energy deposition was captured, and the controlling mechanism under different exciting power and frequency was explored. The results showed that the blast wave induced by PADs had a strong impact on SWBLI structures and distorted the separation shock wave. During the downstream propagation, the controlling gas bubbles (CGBs) delivered a continuous thermal excitation to the boundary layer and reached the maximum penetration depth near the semi-cylinder. The arc discharge in the SWBLI region induced larger energy deposition, which made the heating zone obtain the highest initial temperature and longest heating duration. Under the plasma condition of 1 × 1011 W/m3/15 kHz, both the upstream part of the shear layer and the foot portion of the reattachment shock wave were removed. When setting the excitation to 2.5 × 1010 W/m3/60 kHz, a thermal exciting surface of merged CGBs was formed and the separation shock wave was completely replaced by an equivalent compression-wave system. A better drag-reduction effect on the flow field would be produced by the actuator with an increased operating power or frequency, and a drag reduction rate of nearly 25.5% was achieved under the 2.5 × 1010 W/m3/60 kHz control condition. [ABSTRACT FROM AUTHOR]

To reduce the large size of a gunshot recognition network model and to improve the insufficient real-time detection in urban combat, this paper proposes a fast gunshot type recognition method based on knowledge distillation. First, the muzzle blast and the shock wave generated by the gunshot are preprocessed, and the quality of the gunshot recognition dataset is improved using Log-Mel spectrum corresponding to these two signals. Second, a teacher network is constructed using 10 two-dimensional residual modules, and a student network is designed using depth wise separable convolution. Third, the lightweight student network is made to learn the gunshot features under the guidance of the pre-trained large-scale teacher network. Finally, the network's accuracy, model size, and recognition time are tested using the AudioSet dataset and the NIJ Grant 2016-DN-BX-0183 gunshot dataset. The findings demonstrate that the proposed algorithm achieved 95.6% and 83.5% accuracy on the two datasets, the speed was 0.5 s faster, and the model size was reduced to 2.5 MB. The proposed method is of good practical value in the field of gunshot recognition. [ABSTRACT FROM AUTHOR]

In various situations, targets with different characteristic dimensions are being exposed to blast waves generated by high explosive detonation. One of the existing mitigation methods consists of protecting the target from the explosion with a sandwiched crushable core between a front plate and the target. The pressure generated by the explosion is converted into the planar displacement of the front plate, which compresses the crushable core, delaying the transmission of the load to the target. The influence of the crushable core on the transmitted load in the form of a plateau stress is well described in the literature contrary to its influence on the transferred momentum. In this paper, momentum transmission during the crushing of the core has been experimentally investigated, taking into account the fluid–structure interaction effect, the mechanical behavior of the core, and the pneumatic effects generated by the air trapped into its cells. It is shown that the beneficial effects of fluid–structure interactions are often counterbalanced by the mechanical behavior of the core and that analytical models from the literature are sufficient to describe the order of magnitude of the uniaxial crushing process. [ABSTRACT FROM AUTHOR]

The paper presents modelling and simulation of a local blast wave interaction with a tire of a logistic truck supporting military operations. In the military industry, it is desired to improve effectiveness and strength of vehicle components and simultaneously to minimize the risk of crew injuries. Therefore, the main goal of this paper is to present an attempt to improve blast resistance of a tire. Based on the developed, verified and validated finite element model an optimization procedure was conducted to minimize the damage of a tire subjected to a blast wave. The main issue in the performed computations was to estimate an influence of the cords angle in each layer. For this purpose, a pre-processor script was developed in order to easily modify the finite element model so that the generation process was performed automatically on the basis of optimization variables. Dynamic response of a tire subjected to blast wave in different cases (cords configurations) was analyzed. It was shown that the optimized cords angles configuration reduces tire local damage and increases its blast resistance. [ABSTRACT FROM AUTHOR]

The propagation characteristics of blast waves and the prediction accuracy of blast vibration velocities along negative slopes are important because those can be used to guide engineering application and theoretical research. In this paper, the wave theory was applied to better understand the propagation mechanism of blast waves along negative slopes. Regression analysis was used for the Sadovsky and the CRSRI blast vibration velocity prediction models during on-site operations. The magnification of peak blast vibration velocity along a negative slope was introduced to determine the threshold altitude difference for the magnification effect to occur. Based on this parameter, the relative errors between the two prediction models were compared. The obtained results indicate that the superposition of incident and reflected blast waves on a negative slope creates the "slope effect" which locally amplifies the blast vibration velocity. The relative error of the CRSRI prediction model was as small as 17.53%, demonstrating a greater accuracy than Sadovsky's prediction model. The magnification effect of a negative slope was observed at specific altitude differences and was more noticeable in the perpendicular direction. This paper creates a theoretical basis for studying the propagation mechanisms of blast vibration waves along negative slopes as well as predicting the blast vibration velocities. [ABSTRACT FROM AUTHOR]

This paper investigates the influence of real-gas effects in fluid–structure-interaction while estimating high-intensity air-blast loads and its subsequent implications on the crushing of metallic sandwich panels. It is well known that at high pressure and temperature, nitrogen and oxygen molecules present in the air undergoes ionization and dissociation, which may, in turn, lead to higher stagnation pressure upon reflection from a wall. However, almost all fluid–structure-interaction models use the ideal-gas assumption even at very high pressure and temperature in estimating air-blast loads to simulate core compression of sandwich panels. In the present work, a new method is proposed to predict air-blast loads on free-standing metallic sandwich panels considering electronic excitation, ionization, and dissociation of the constituents in the air during fluid–structure-interaction. One-dimensional dynamic response of free-standing sandwich panels due to air-blast loads, which is computed based on the proposed method, is investigated and compared with other existing theories based on ideal-gas. The interaction of the panel with the fluid beyond, i.e., air-backed and water-backed conditions, is also studied. Real-gas effects in the air at the backside are also investigated and compared with the ideal-gas based backing condition. The study reveals that using ideal-gas based fluid–structure-interaction models in predicting high-intensity air-blast loads on sandwich panels leads to an under-prediction in core compression and plastic dissipation for the same "crushing strength to incident over-pressure ratio." Therefore, ignoring real-gas effects in the fluid–structure-interaction phase while designing the low-density core of a sandwich panel for high-intensity air-blast mitigation can be detrimental and may lead to catastrophic failure. [ABSTRACT FROM AUTHOR]

This paper investigated the blast behavior of a low‐rise composite steel structure of three stories subjected to internal and external explosions for the same explosive charge of 250 kg TNT. A comparison of three various blast scenarios is aimed at better understanding how blast waves propagate in confined risk zones and their damage effects on far and exposed elements to an explosive charge. Evaluation of the damage level and the overall response of the proposed numerical model is done by estimating the adequacy of structural members subjected to blast loading using general limits in attempting to check the structure's strength and regularity. The analysis was based on load combinations and damage criteria according to the Unified Facilities Criteria which are general design approaches suitable for civil design applications in forecasting blast loads and structural system responses. The overall behavior of this structure was simulated based on a dynamic analysis by the direct simulation approach, which was chosen for modeling blast loads using the Friedlander blast load equation, and the simpler, less expensive, more accurate, and realistic A.T.‐BLAST model to deduce the simplified blast‐wave overpressure profile. The material nonlinearity at a high strain rate using the Johnson‐Cook strength and concrete plasticity damage model is studied dynamically using ABAQUS finite element code to simulate the explicit dynamic nonlinear analysis. The overall response of the proposed numerical model was evaluated by estimating the adequacy of structural members, considering the blast load as the initial cause of failure, such as axial plastic strain, internal forces limits, maximum deformation, support rotation, demand‐capacity‐ratio (DCRshear/moment), drift index and material damage model. The position of the explosive charge played an important role in determining the rate at which the structural element begins to plastic strains, displacements, moments, or rotations beyond the limits, and then key elements should be considered in structural design against progressive collapse. Results showed that steel members exhibit early indicators of failure, such as buckling necking, shear tearing, or plastic hinges, whereas concrete slabs break up immediately due to brittleness. DCRmoment values successfully showed the columns in which the first plastic joint can occur, whereas DCRshear values signaled the onset of shear failure at connections. Besides, plastic hinges played an important role in dissipating energy and preventing total structural collapse via the Strong Column‐Weak Beam design concept, which appears repeatedly in this study. The structure is a well‐designed and ductile building capable of supporting higher loads and is considered to be repairable and intact. [ABSTRACT FROM AUTHOR]

Trenches, as important practical military facilities, have important theoretical and military value in evaluating the damage power of ammunition, operational application, and effective safety protection of personnel on the battlefield through the spatiotemporal evolution of explosive shock waves within them. At present, there is a lack of in-depth research on the distribution and impact of overpressure inside the trench. The paper constructed a typical finite element simulation model of a trench, numerically calculated the shock wave overpressure inside the trench and on the wall, analyzed the spatiotemporal distribution of shock wave pressure in various parts of the trench, conducted on-site explosion tests, and installed shock wave pressure sensor measurement points in the trench. The pressure time history curve was obtained, and verified and compared with the simulation calculation results. Research data shows that the peak overpressure of the shock wave in the trench increases sequentially from the front wall to the back wall. The peak overpressure of the shock wave at the front wall attenuates by 10 % to 20 % compared to the inside of the trench, and increases by 40 % to 60 % at the back wall; The peak overpressure in the trench exhibits a "V-shaped" distribution at different depths, decreasing first and then increasing as the depth increases. The maximum overpressure peak increases by 40 % to 50 % compared to the minimum; Based on simulation and measured data in the trench, as well as the distribution law of shock wave pressure, safety protection suggestions for on-site combat personnel in the trench are provided. [ABSTRACT FROM AUTHOR]

The cutting blasting project of the Hehui Expressway is close to existing buildings. Vibration reduction measures based on a fine blasting design are put forward to ensure the safety of the project and existing buildings. The project is divided into three blasting areas for construction. This paper investigates "first middle and then edge" and "first edge and then middle" blasting sequences and the vibration responses of adjacent buildings. For the cutting blasting project of the Hehui Expressway, the different blasting sequences are investigated according to the positional relationship between three blasting areas and an existing village, and a reasonable blasting sequence is determined through numerical simulation, on-site blasting tests, and the on-site vibration response data of adjacent buildings. The results show that the existing buildings can be effectively protected by changing the construction sequence of the blasting area on the premise of ensuring the effectiveness and safety of construction. Zone II can be regarded as a huge blasting isolation hole that plays a positive role in the control and attenuation of the blasting stress wave. Blasting in Zone II thus has an excellent vibration reduction effect exceeding 90%. With the adoption of the "first middle and then side" construction sequence, the maximum particle velocity of existing buildings under the action of the blasting stress wave is 1.1 cm/s, which is within a reasonable safety range. [ABSTRACT FROM AUTHOR]

Three-dimensional numerical simulation of spinning detonation in a square tube is carried out using the time-dependent, reactive Euler equations with detailed H2/air chemistry. A two-dimensional simulation of single-head detonation is also performed at similar conditions for the purpose of comparison with three-dimensional simulation. The pseudo-detonation phenomenon that appears in the flow field of spinning detonation at low resolution is revealed by a resolution study, indicating that a suitable grid resolution is necessary for reproducing the real spinning detonation under present conditions. Subsequently, a representative pattern of helical strips left by the spinning detonation on the wall of square tube is carefully analyzed under limiting propagation conditions. Our results show that the transverse wave structure behind the detonation front for both two- and three-dimensional cases can be featured by a second kind of strong transverse wave structure defined in this paper, and such structure lead to the generation of a number of unreacted pockets downstream the front. Furthermore, the results demonstrate that the blast dynamics instead of the transverse detonation wave dominates the propagation of spinning detonation in present study. The blast kernels, including line blast kernels and point blast kernels, promote the heat release and subsequently support the spinning detonation in the square tube. Finally, the results indicate that the out-of-phase collisions between the triple lines on the leading shock front lead to the resonant coupling between the reaction surface and the shock front, permitting the detonation to propagate self-sustainingly in the lowest mode within a square tube. [ABSTRACT FROM AUTHOR]

To explore the dynamic crack propagation behaviour in the fracture zone and the damage characteristics of the rock mass around the blasthole during eccentric uncoupled blasting of a deep-level rock mass, theoretical analysis, model experiments and numerical simulation studies have been described in this paper. Firstly, the stress state of the crack and the stress distribution state and failure mechanism of the rock mass around the blasthole under the influence of the in-situ stress, and the pressure distribution of blast shock wave on the blasthole were analysed. Secondly, with the help of a new digital laser caustics experimental system, the eccentric uncoupled blasting model experiment under the action of the in-situ stress was carried out. The fractal damage theory is used to quantitatively evaluate the damage degree of the rock mass in different areas around the blasthole, and the blast-induced crack propagation mechanical behaviour characteristics in the fracture zone are analyzed from the perspective of dynamics. Then, based on the LS-DYNA software, a numerical simulation study was conducted on the eccentric blasting of deep rock mass. Finally, some discussions and suggestions are provided for the analysis of blasting mechanisms in a deep-level rock mass. [ABSTRACT FROM AUTHOR]

In large equivalent explosion tests, the method of calculating blast wave parameters by the plastic deformation angle of a cantilever beam can effectively avoid the problem of power supply, storage, communication, and low survival rate of conventional blast wave sensors. In this paper, by means of theoretical analysis and numerical simulation, the deformation response of a pure aluminum cantilever beam with different scaled distances is calculated, and the relationship between the plastic bending angle and blast wave parameters is obtained, which provides a novel and effective method for the measurement of blast wave parameters. The experimental results show that the deformation of the cantilever beam is mainly dominated by the impulse load and the error of this measurement method is within 15%. This method can provide a complementary approach to more precise but complex sensor measurement and can effectively evaluate the impulse in the explosion accident outside. [ABSTRACT FROM AUTHOR]

Explosions in an urban setting can have a significant negative impact. There is a need to further understand the loading effects caused by the blast's interaction with structures. In conjunction with this, the effects of scaling and understanding the limitations of laboratory experiments are equally important given the cost incurred for full-scale experiments. The aim of this study was to determine the scaling effects on blast wave parameters found for reduced-scale urban blast scenario laboratory experiments. This paper presents the results of numerical modelling and physical experiments on detonating cuboidal PE-4 charges and measuring the pressure in direct line of sight and at three distinct positions around the corner of a small-scale "building" parallel to the rear wall. Two scales were used, namely 75% and 100%. Inter-scaling between 75% and 100% worked fairly well for positions shielded by the corner of the wall. Additionally, the lab-scale results were compared to similar (but not identical) field trials at an equivalent scale of 250%. The comparison between lab-scale idealised testing and the larger-scale field trials published by Gajewksi and Sielicki in 2020, indicated sensitivity to factors such as detonator positioning, explosive material, charge confinement/mounting, building surface roughness, and environment. [ABSTRACT FROM AUTHOR]

On April 9, 2018, a massive rock avalanche hit the area of Karimabad, Hunza. Approximately 2Mm3 of rock mass detached from the source area and traveled a total of 4.88 km. The rock mass deposited along 2000 m length and destroyed the Ultar meadows. The avalanche killed three tourists and resulted in a vast dust cloud that engulfed the entire town of Karimabad in a few seconds. In this paper, we have analyzed the dynamic characteristics of the Ultar rock avalanche and subsequent airblast using a coupled three-dimensional discrete element modeling and computational fluid dynamics approach. Two-way coupling was carried out using an application programming interface that transferred the data between models to simulate the avalanche movement and induced airblast. We have also analyzed the formation and propagation of induced dust clouds based on field investigation, captured video, and climatic conditions. The study concludes that the Ultar rock avalanche's movement lasted 148 s. The average velocity of sliding material was found to be 26.35 m/s. The dynamics of induced airblast were studied along the entire runout path. The maximum velocity of generated airblast along different sections of the runout path was found to be 40 m/s and 35 m/s, respectively, whereas the relative pressure of the blast wave was found to be 0.6 kPa. Furthermore, the results revealed that a low-pressure dust cloud traveled a long distance due to the continuous fragmentation of the sliding material along a steep runout path. The induced dust cloud engulfed the entire town of Karimabad, Hunza, for several hours. This study is expected to help scientists further explore the dynamics of the airblast. It will also help understand the formation and propagation of dust clouds induced by rock avalanches involving excessive fragmentation. [ABSTRACT FROM AUTHOR]

Experiments and numerical simulations of shock wave/turbulent boundary layer interaction (STBLI) disturbed by arc plasma energy deposition (APED) were carried out in this paper. The experiments were conducted in a M = 2.497 wind tunnel. Both the flow structures and the evolution process of impinging STBLI disturbed by APED were captured by time-resolved schlieren imaging. The disturbance effects of APED on supersonic flow without STBLI were studied with different capacitor stored energies. Furthermore, under the same capacitor stored energy, the impinging STBLI control with APED were explored in different flow deflection angles. The experimental results indicated that thermal bubbles induced by APED had a high penetration depth and impacted the STBLI seriously. Compared to the incident shock wave, the separation shock wave was more sensitive to the influence of APED and showed significant instability. With equivalent energy deposited into the flow, the ability of APED to disturb the impinging STBLI was decreased as the flow deflection angle increased, and the separation shock wave had a smaller position change and shorter recovery time. The direct numerical simulation results showed that the APED added in a flow field can hinder the velocity development of the turbulent boundary layer. The unsteadiness of separation shock waves was induced by both thermal bubbles and blast waves, and the thermal bubbles' effects were dominant. They would modify the compressibility of the boundary layer and enlarge the separation zone, which contributed to the separation shock wave's dispersion and movement. [ABSTRACT FROM AUTHOR]

Computational fluid dynamics is a useful tool for investigating various cases when estimating the physical hazard of high explosives. This paper presents a test case to discuss the effect of a rigid barrier wall on the blast wave behavior of a high explosive. A condensed matter analysis program for highenergy materials (KHT2009) was used to obtain the properties of the detonation products. We modeled the detonation products with the equation of state for an ideal gas, and the initiation process of the high explosive was neglected. The wall was close to the high explosive and interacted with the initial blast wave and detonation products. An additional higher wall was installed over a standard barrier wall around an azimuth angle of 0°. The azimuthal distributions of the peak overpressures were compared for previously obtained experimental results and the present numerical results. The multiple reflected and diffracted waves off the wall produced complex flow patterns that were responsible for the azimuthal distribution of the peak overpressure. To secure a longer distance and time before the reflected wave from the additional higher wall intensifies the incident blast wave along 180°, and to achieve greater mitigation beyond and near the wall along 0°, we recommend that the additional higher wall be located as far as possible from the high explosive.Computational fluid dynamics is a useful tool for investigating various cases when estimating the physical hazard of high explosives. This paper presents a test case to discuss the effect of a rigid barrier wall on the blast wave behavior of a high explosive. A condensed matter analysis program for highenergy materials (KHT2009) was used to obtain the properties of the detonation products. We modeled the detonation products with the equation of state for an ideal gas, and the initiation process of the high explosive was neglected. The wall was close to the high explosive and interacted with the initial blast wave and detonation products. An additional higher wall was installed over a standard barrier wall around an azimuth angle of 0°. The azimuthal distributions of the peak overpressures were compared for previously obtained experimental results and the present numerical results. The multiple reflected and diffracted waves off the wall produced complex flow patterns that were responsible for the azimuthal distribution of the peak overpressure. To secure a longer distance and time before the reflected wave from the additional higher wall intensifies the incident blast wave along 180°, and to achieve greater mitigation beyond and near the wall along 0°, we recommend that the additional higher wall be located as far as possible from the high explosive. [ABSTRACT FROM AUTHOR]

Cylindrical shells are widely used in public buildings and military protection fields, and it has a high risk of terrorist attacks and military attacks, it is of great social benefit to carry out the anti-blast design of cylindrical shells, which needs to consider building shape and the shape of blast waves. In this paper, cylindrical charges in five directions were detonated on the outer ground of the scaled cylindrical shell, blast loads of the cylindrical shell were measured and blast waves were photographed. The variation of blast load is analyzed by combining the test and simulation results, the difference in peak overpressure of the blast waves on the end face between five orientations is nearly twice. The blast loads in the axial direction of cylindrical charges have a secondary peak phenomenon, and the blast loads between the axial direction and radial direction of cylindrical charges change abruptly at a specific angle. The experimental and simulation methods provide a reference for establishing a blast load database of typical buildings. [ABSTRACT FROM AUTHOR]

The aim of the present paper was to report on an experimental study of the characterization of a blast wave initiated by a solid explosive and its interaction with a rigid obstacle in the form of a hemicylinder. Pressure transducers located along the path of the blast wave and high-speed imaging allow (1) the measurement of the overpressure at different locations and (2) the characterization of the blast wave inception, propagation, and reflection off the hemicylinder. The scaling effect has been investigated by performing experiments in two different facilities, where one is at twice the scale of the other. [ABSTRACT FROM AUTHOR]

Public buildings that house large populations are easy targets for terrorist attacks, the primary issue of architectural blast-resistant design is how to get blast loads on the surface of structures, and the shapes of blast waves and buildings both have important effects on it. In this paper, experiments and numerical simulations were carried out on blast loads on the surface of the cylindrical shell. blast loads, detonation products, and blast waves were well recorded and simulated, blast loads at the edge of cylindrical shells were attenuated by about 75%, and vortex rings were accidentally photographed nearby. blast loads are much affected by the location of the detonation point, charge shape, and charge size. The original shape of structures rather than deformation determines the distribution of blast loads, the air viscosity also needs to be scaled when using a scaled model to test blast loads. Experimental and simulation methods can offer a reference for building a standard database of blast loads. [ABSTRACT FROM AUTHOR]

The blasting vibration has an impact on the rock and soil around the blasting hole and the nearby structures. The vibration-isolating slot is one of the methods to reduce the damage of blasting vibration. In this paper, the influences of the depth and position of the vibration isolation slot on the PPV (peak particle velocity) attenuation characteristics of the ground vibration and blasting vibration damping effect of the vibration isolation slot at different measuring points are studied systematically by LS-DYNA numerical models. The results show that the damping effect of the vibration isolation slot is realized by reflecting the blasting vibration wave and increasing the propagation paths of the blasting vibration wave. When the measuring points are 5 m∼45 m far away from the vibration-isolating slot, the average vibration damping effect of the vibration-isolating slot is more than 30% and the deeper the depth of the vibration isolation slot, the better the vibration damping effect when the measuring points are 5 m∼15 m far away from the vibration isolation slot. However, when the measuring points are 15 m∼45 m far away from the vibration isolation slot, the vibration damping effect is best when the depth of the vibration isolation slot is 15 m. The vibration damping effect of blasting vibration at the same measuring point is different due to different positions of vibration isolation slot. For the measuring points M3 and M5, with the increasing of the distance between the vibration-isolating slot and the explosion source, the vibration damping effect of the vibration-isolating slot shows an increasing-decreasing-increasing trend; however, it shows a decreasing-increasing-decreasing trend for the measuring point M4. [ABSTRACT FROM AUTHOR]

Asteroid impacts can cause a wide range of damage through multiple potential hazards, from localized blast waves or thermal radiation, to tsunami inundation, to global climatic effects. The level of risk posed by these hazards depends not only upon their extent and severity, but also upon the likelihood of the various damage ranges. Some consequences may be more moderate but very likely, while others may be unlikely but catastrophic. Evaluating the risk from these hazards involves substantial uncertainties across all aspects of the problem, including the properties of the asteroid, the specifics of its entry, and the complex high-energy damage physics involved. NASA's Asteroid Threat Assessment Project (ATAP) performs Probabilistic Asteroid Impact Risk (PAIR) assessments that use fast-running entry and hazard models to evaluate millions of impact cases representing the distributions of these many uncertain parameters. This paper presents the current PAIR modeling tools and approaches used for evaluating specific asteroid impact threat cases. We give an overview of the current PAIR model used to support hypothetical impact threat scenarios and discuss some of the key applications of these assessment in supporting planetary defense response and preparedness. We then present the results and key findings from the recent 2023 PDC hypothetical impact exercise as an example of the primary types of risk results and metrics being developed to inform potential mitigation and response decisions. The 2023 PDC scenario represents an impact threat from a large 800-m asteroid with an initial uncertain size range from ∼150 m to 2 km in diameter, spanning sizes that would cause only local damage to sizes that could potentially cause tsunamis or global effects. Results demonstrate key assessment and response challenges for such large impact scenarios, and motivate the need for further modeling and simulation studies to better understand the potential onset and severity of regional and global-scale hazards. • Probabilistic risk assessments support response decisions for asteroid threats. • Assessment of the 2023 PDC impact scenario demonstrated key response challenges. • Global effects were a major risk driver despite their low probability. • Asteroid size and damage uncertainties underscore the need for rapid space missions. • Results motivate simulation studies of large impact hazards to improve risk estimates. [ABSTRACT FROM AUTHOR]

The design of blast-resistant structures and protective systems requires a firm understanding of the loadings imparted to structures by blast waves. While empirical methods can reliably predict these loadings in the far field, there is currently a lack of understanding on the pressures experienced in the very near field, where physics-based numerical modelling and semi-empirical fast-running engineering model predictions can vary by an order of magnitude. In this paper, we present the design of an experimental facility capable of providing definitive spatially and temporally resolved reflected pressure data in the extreme near field ( Z < 0.5 m/kg 1 / 3 ). The Mechanisms and Characterisation of Explosions (MaCE) facility is a specific near-field evolution of the existing Characterisation of Blast Loading (CoBL) facility, which uses an array of Hopkinson pressure bars embedded in a stiff target plate. Maraging steel pressure bars and specially designed strain gauges are used to increase the measurement capacity from 600 MPa to 1800 MPa, and 33 pressure bars in a radial grid are used to improve the spatial resolution from 25 mm to 12.5 mm over the 100 mm radius measurement area. In addition, the pressure bar diameter is reduced from 10 mm to 4 mm, which greatly reduces stress wave dispersion, increasing the effective bandwidth. This enables the observation of high-frequency features in the pressure measurements, which is vital for validating the near-field transient effects predicted by numerical modelling and developing effective blast mitigation methods. [ABSTRACT FROM AUTHOR]

Floating pontoons have played a supreme and indispensable role in crises and disasters for both civil and military purposes. Floating bridges and ferries are exposed to blast loadings in the case of wars or terrorist attacks. The protection effectiveness of sacrificial cladding subjected to a blast was numerically investigated. In this study, a steel ferry has been simulated and exposed to side explosions with different explosive charges at certain stand-off distances, according to military standards from NATO and American standard TM5. In this simulation, nonlinear three-dimensional hydro-code numerical simulation ANSYS autodyn-3d has been used. The results reported that the ferry could withstand a charge of 5 kg TNT at a stand-off distance of 1 m without failure. The main objective of this research is to achieve a design that would increase the capacity against the blast loading with minimal plastic deformation in the absence of any failure in the ferry. Therefore, an innovative mitigation system has been proposed to dissipate the blast energy of the explosion based on the scientific theory of impedance using sacrificial cladding. The new mitigation system used a specific structural system in order to install the existing pontoon structure without any distraction. The response, elastic deformations, plastic deformations and plastic failure of the ferry were illustrated in this paper. Furthermore, the results revealed that the proposed mitigation system could mitigate more than 50% of the blast waves. The new design revealed promising results, which makes it suitable for mitigating blast waves. Finally, the results were provided with a reference for the preliminary design and application of sacrificial cladding for structural protection against blast waves. [ABSTRACT FROM AUTHOR]

Blast waves generated by energetic materials involve very fast time variations in the pressure. One important issue for blast wave metrology is the accurate measurement (typical precision in the range of ±5% or better) of the static overpressure peak. For most near field configurations, this measurement requires ultra-fast sensors with response times lower than a few microseconds. In this paper, we design, model, fabricate and characterize a new ultra-fast sensor using piezo-resistive gauges at the center of a miniaturized and rectangular silicon membrane. When a pressure step of 10 bar is applied to the membrane, the signal delivered to the sensor output presents dampened oscillations, with a resonant frequency of 20.6 MHz and quality factor of 24,700 ns after the arrival of the shock wave. After removing undesirable drifts that appear after 700 ns, we may expect the sensor to have a response time (at ±5%) of 1.2 µs. Consequently, the proposed pressure sensor could be advantageously used for the accurate measurement of static overpressure peaks in blast wave experiments. [ABSTRACT FROM AUTHOR]

This paper presents the results of detonation and explosion characteristics for ammonium nitrate, aluminium, and aluminium-magnesium alloy powder mixtures. The following parameters were determined: detonation velocities, blast waves overpressure and their specific impulses. The emission of radiation was recorded, and the history of temperature of the detonation products cloud was established. It was shown that addition of aluminium-magnesium alloy powder increases blast waves' characteristics. Moreover, it increases the time of the afterburning reaction after detonation and increases the temperature of detonation products. [ABSTRACT FROM AUTHOR]

In this paper, 30 SFRC (Steel Fiber Reinforced Concrete) spindle specimens with different steel fiber contents were subjected to static loading tests and blast wave loading tests on spindle specimens with different steel fiber contents using a self-developed planar blast wave loading device (a new type of patent recognized by the State Intellectual Property Rights). The dynamic response, impact performance and damage mode of Steel Fiber Reinforced Concrete under blast loading were investigated. The experimental results show that with the increase of steel fiber content (within 2%), the strength of the Steel Fiber Reinforced Concrete increases slightly. The flatter the falling section of the stress-strain curve, the better the energy absorption effect. With the increase of explosive equivalent(24 g RDX and 36 g RDX), the more obvious the strain rate effect, the greater the increase of peak stress, and the SFRC with 2% steel fiber content has the best energy absorption effect. Furthermore, the dynamic response of SFRC spindle specimens was numerically simulated using the improved K&C material model with LS-DYNA explicit finite element dynamic analysis software. The results verify the validity and reliability of the improved K&C material model. [ABSTRACT FROM AUTHOR]

An explosion inside a cabin will converge at the corners to form high-pressure areas, significantly impacting the destruction of a bulkhead structure. This paper investigates shock wave convergence characteristics at the corners when the explosive detonates at the center of the cabin, based on a combination of the wall reflection law for shock waves and a numerical simulation method. The parameter K represents the aspect ratio of the cabin structure. This study shows that when 1 ≤ K ≤ 1.19, the high pressure at the corner is caused by the superposition of Mach waves along both wall surfaces. However, for the initial shock wave, when 1.2 < K ≤ 2, the high pressure is caused by the superposition of Mach waves along the longer wall surface and regular reflected waves on the shorter wall surface; when 2 < K, the cause are Mach waves along the longer wall surface and the corresponding positive reflection on the shorter wall surface. The influence of K on the range for the high-pressure region at the corner is also analyzed, the functional relationship between the range of the high-pressure area and K is given, and the universality is verified. [ABSTRACT FROM AUTHOR]

The paper studies the flexural responses of one-way reinforced concrete structural elements subjected to cased explosive charges to explore the suitability of using high-strength materials for such scenarios. The detonation of cased explosive charges leads to the generation of fragments due to the rupturing of the casing housing the high explosive charge. Consequently, structures subjected to the detonations of cased explosive charges are acted upon by both the blast wave (due to the detonation of the high explosive charge) and the fragments. This study was motivated by the fact that although similar studies have been conducted to explore the suitability of using high-strength materials for scenarios involving bare (uncased) explosive charges, such studies are still uncommon when it comes to cased explosive charges. The methodology adopted herein consisted of developing a semianalytical approach that was validated against (1) the results of experimental static tests available in the literature, (2) the results of experimental blast trials conducted with bare (uncased) explosive charges that are available in the literature, and (3) the results of finite-element simulations, conducted by the authors due to the nonavailability of a relevant experimental data set in the public domain pertaining to cased explosive charges (to the best of the authors' knowledge). Following the validations, the adopted semianalytical approach was further used for conducting detailed parametric investigations. It was observed that compared with the lightly cased explosive charge (casing to charge mass ratio=0.5), the peak structural displacements for the heavily cased explosive charge (casing to charge mass ratio=1.5) showed an increase of 50% (for high-strength materials) to 64% (for normal-strength materials). Moreover, compared with normal-strength materials, the application of high-strength materials was also noted to reduce the peak structural displacements by 9% to 23%, which indicated the increased measure of safety provided by the high-strength materials. In addition to this, compared with normal-strength concrete, the employment of high-strength concrete grades was also effective in limiting the fragment inflicted damage by 25% to 36%. Additionally, increasing the reinforcement ratio to 0.65% from 0.16% effectively reduced the peak structural displacements by 57% to 63%. [ABSTRACT FROM AUTHOR]

• A new peridynamic model is presented to study the explosive blast effects on solids. • Failure behaviors of steel and aluminum plates are investigated in explosions. • A parametric study is conducted to examine the impact of different blast parameters. • New guidelines are proposed to enhance the explosive blast resistance of solid plates. The paper presents a novel and efficient model to examine deformations and fractures in solid plates when exposed to explosive blast events under various scenarios and boundary conditions. The proposed model uses the peridynamic method to simulate the motion and damage of solid plate particles during explosions in a mesh-free scheme. The model's validation with experimental results is essential to ensure that the proposed model can capture the actual behavior of solid plates in explosive blasts. The present study shows the following novelties: (1) A novel coupling strategy is presented, which integrates explosive blast loadings with the peridynamic method. Therefore, the model becomes capable of effectively capturing the interactions between explosive blasts and solid plates; (2) The proposed model demonstrates remarkable stability in modeling explosive blasts on solid plates, and it does not require refinement schemes nor adaptive modeling parameters such as adaptive timestep; (3) The peridynamic model overcomes the mesh-distortion issues commonly encountered in mesh-based models, particularly under extreme loading conditions; (4) The proposed model exhibits high efficiency, enabling fast and accurate simulations of solid plate behavior under explosive blast scenarios. The paper also presents a new parametric study that explores the failure behavior of solid plates during explosions. [ABSTRACT FROM AUTHOR]

In this paper, confined explosions of HMX-based aluminized explosives in a spherical chamber are studied. The effects of aluminum particles on the afterburning reaction and explosive performance are obtained by changing the size of the particles and the gas environment. The results show that the concentration of oxygen in air is not sufficient to support complete combustion of aluminum particles. The estimated oxidation rate of aluminum particles is 87–93%, and it tends to decrease with increasing particle size. Part of aluminum particles oxidize with detonation products, and the reaction can last for hundreds of microseconds. However, the degree of oxidation between the large-sized aluminum particles and detonation products is small. A new method is used to estimate the initial energy of detonation by observing the time difference between sensing the initial light and the pressure wave. This method leads to a conclusion that some of the aluminum particles are oxidized during detonation and provide additional energy to the primary blast wave. Small micron-sized aluminum particles in the range of 48.9 nm to 46.7 m extend the duration of the fireball. [ABSTRACT FROM AUTHOR]

Large-scale landslides as a common geological hazard can be easily triggered by natural factors, while it is extremely difficult to be activated by anthropolical blasting operations. The paper presents a comprehensive analysis of characteristics of stress wave propagation in a blasting-triggered large-scale rockslide, termed Wangshan–Zhuakousi Landslide, to investigate the effect of blasting wave on multi-layer interface condition. A detailed analysis of the propagation of P wave in the filling joints was conducted to verify the reliability of the analytical model and the deterioration characteristics of the weak interlayer. The results indicate that the reflection tensile wave can be formed when P wave propagates from the basalt across the tuff interlayer. The theoretical equation for damage assessment of soft rock interlayers is proposed, which can be adopted in calculating the additional stress of soft rock mass in blasting operation. It is found that the material density is the most influential factor in attenuation rate. Besides, the longitudinal wave velocity of materials and the period of incident waves perform the identical effect on the attenuation rate. It is demonstrated that the cumulative failure of tuff layer plays a crucial role in triggering successive sliding. According to the modelling, the tuff interlayer appears to be in a compressed state before the complete damage under P-wave propagation. The locally tensile behaviour can be observed after the complete damage of the tuff. The underlying tuff interlayer forms a discontinuous cumulative damage zone, which significantly triggered major ruptures and destabilized the original bedding rock slope. This paper could prove new insight towards the enforcement of risk assessments and mitigation countermeasures for blasting-induced landslide. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the effect of confinement on the explosion characteristic of a certain volume of a gas mixture in an environment. Instead of using the equivalent weight of TNT, we use a computational fluid dynamics method with a reduced chemical kinetic mechanism to simulate the gas mixture detonation. In this method, reacting flow equations including realistic finite-rate chemistry models are solved by employing the space-time conservation element and solution element (CESE). To evaluate the accuracy of the kinetic mechanism and the validity of the simulation of the volumetric explosions, including the blast wave propagation and its interaction with the walls, the explosion of a certain volume of stoichiometric propane/oxygen mixture in a semi-confined volume is investigated and the numerical results are compared with an experimental data. The excellent agreement between the numerical results and the experimental data indicates that it is possible to predict the behavior of the blast wave generated by the detonation of a gas mixture in a relatively complex environment accurately by using appropriate chemical kinetics. Therefore, we have used this method to investigate the effects of confinement on the blast wave propagation caused by gas detonation in more detail. [ABSTRACT FROM AUTHOR]

This paper presents the results of detonation parameters for ammonium nitrate-polyhydroxy alcohol mixtures and ternary explosive compositions modified by flaked aluminium. The detonation velocities, overpressures of blast waves and their specific impulses were determined. It was shown that the viscosity of liquid fuels is the leading property that determines the detonation parameters of the tested compositions. [ABSTRACT FROM AUTHOR]

Requirements for explosive safety are often given in terms of a "K-Factor", correlating incident blast effects with the distance and TNT equivalent weight of an explosion. Traditionally, this is conducted using empirical correlations to experimental measurements (e.g., the Kingery–Bulmash equations). In the far-field, empirical verification of incident overpressure and impulse magnitudes can be difficult; extrapolations from data give expected values at reasonable standoff distances that sometimes are too small to measure on available equipment but are larger than some regulations require. The present paper describes the results of numerical hydrocode analysis to verify the expected incident overpressure and impulse from small hemispherical ground charges of TNT at these relatively large distances. Furthermore, the dynamic effect of incident blast waves on lightweight, modular mitigation barriers is studied to gauge their effectiveness at providing safety standard compliance. [ABSTRACT FROM AUTHOR]

In this paper, an initial pressure adjustable explosion vessel was developed, and the effect of negative pressure, positive pressure (0.2–1.8 atm) different initial ambient pressure on the explosive shock wave generated by the explosion of explosives was studied. The relationships between the specific impulse, shock wave velocity, the amount of explosive gas products and the ambient pressure were analyzed for different initial pressure environments. It was found that: the overpressure of the blast shock wave decreases with the initial ambient pressure of the explosion, and there exists a negative pressure environment with a dramatic pressure decrease near 0.6 atm, defined as the super-sensitive negative pressure Pcr. The propagation velocity of an explosive wave increases with a decrease in the ambient pressure, and the propagation velocity at a pressure of 1.8 atm is four times less than the velocity at a pressure of 0.2 atm. The production of explosive gas products did not change. The greater the initial pressure of the environment where the explosive is located, the smaller the ratio of the gas generated by the explosion to the initial force gas in the explosion vessel is, and the greater the impact on the propagation of shock waves is. The maximum attenuation of the first specific impulse i1 is 72.97% and the maximum attenuation of the second specific impulse i2 is 72.39%. The experiments provide reference data for high-altitude military confrontation, high-altitude weapons and ammunition development, and deep-earth protection engineering. [ABSTRACT FROM AUTHOR]