Blast Wave Propagation Research Articles

A two-scale approach to widen a predictive blast propagation model around a hemicylindrical obstacle

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.

Numerical study of a near-field explosion using arbitrary Lagrangian–Eulerian mapping technique

This study adopted the LS-DYNA mapping algorithm to implement a numerical simulation of a near-surface burst and steel plate non-contact explosion experiments. The rationality and reliability of the mapping technique used in the numerical simulation were validated by a comparison between the experiments and the numerical simulation. The findings showed that the numerical simulation result was consistent with the experimental blast attenuation, meaning the numerical mapping technique could effectively enhance the simulation accuracy and could reflect the experimental blast wave propagation.

Influence of the spatial distribution of underground tunnel group on its blasting vibration response

The spatial distribution of underground tunnels is significant to the stress redistribution in the surrounding rock masses and blast wave propagation. The field blasting tests were first carried out to study the propagation of blast-induced seismic waves through underground tunnels of the Xiluodu Hydropower Station in China. The results show that the peak horizontal particle vibration velocity can be used as a safety criterion for underground tunnels. The effects of in situ stresses and spatial distributions of the tunnel group on the vibration velocities distribution is afterward investigated by numerical simulation. The results show that there is a significant amplification of the blasting vibrations in the adjacent tunnels, which depends on their vertical positions during the excavation of a tunnel. The peak vibration velocity decreases as the lateral separation between tunnels increases. When the separation between the tunnels exceeds the width of three tunnels, the impact of the blast waves on each part of the adjacent tunnel tends to be stable on the whole. In terms of the size of the tunnel, the blasting vibration velocity in the upper part of the straight wall on the front-blast side increases as the width increases (and then levels off), while the blasting vibration velocity in the lower part decreases as the width increases (and then levels off). Finally, a generalized formula of blasting vibration velocity considering the spatial distribution is established, which can well predict the vibration velocity of particles in underground tunnels.

Blast wave propagation characteristics in FPSO: Effect of cylindrical obstacles

The propagations of blast waves on Floating, Production, Storage, and Off-loading unit (FPSO) are influenced by the shapes, dimensions and arrangements of obstacles. In this paper, the effects of cylindrical obstacles on the characteristics of explosion pressures in the process modules of FPSO are studied by using computational fluid dynamic (CFD) method. Defining an effect coefficient η to express the changes of explosion pressures due to the existence of obstacles. It indicates that only the explosion pressures in the limited region adjacent obstacles can be affected by cylindrical obstacles. The increase of obstacle diameter only improve the η values front of the obstacles while increasing obstacle height can significant decrease the explosion pressures behind obstacle. When blast waves propagate multiple obstacles, the explosion pressures adjacent front obstacle are not affected by the rear obstacle, however, the explosion pressures in the gap of two obstacles are relieve due to the existence of front obstacle. The comparisons of effect of cubical and cylindrical obstacles reveal that cubical obstacles have more excellent pressure reduction ability as cylindrical obstacles can provide a larger pressure reduction region.

Evaluation of collapse resistance of masonry-infilled RC frame building under blast loadings

As non-structural members, the masonry-infilled (MI) walls are always ignored in the numerical and experimental study on the blast and collapse resistance of RC frame buildings, while the contribution of MI walls on preventing the large-scale collapse has been observed according to the past explosion incidents. This paper aims to propose and verify a numerical simulation approach considering the blast- and collapse-resistant effects of MI walls, and further evaluate the collapse resistance of MI RC frame buildings under blast loadings. Firstly, based on our previously validated hybrid finite element (FE) modelling approach for RC frame structures and Multi-material Arbitrary Lagrangian-Eulerian method for applying blast loadings, the simplified micro-model and compressive strut model of the MI wall were adopted to characterize its blast and collapse resistance in the near- and far-regions of building, respectively. Secondly, the out-of-plane explosion test and in-plane quasi-static collapse test were numerically reproduced to verify the applicability of adopted FE modelling approaches for MI walls. Furthermore, by establishing the hybrid FE models of prototype bare and MI RC frame buildings, the propagation of blast waves, damage modes as well as dynamic responses of RC frame buildings under two design-based threat of explosion at corner and side columns were derived and examined. Finally, the applicability of the anti-collapse design method specified by U.S. Department of Defense, i.e., alternate path method (APM), for RC frame buildings under external explosions was examined. It derives that, (i) the presence of MI walls can efficiently block the blast waves into the building structures, and relieve the upward arch of slabs and damage degree of interior columns; (ii) compared with the bare RC frame buildings, the MI walls provide sufficient alternate load paths to enhance the structural robustness and restore the gravity stability of MI RC frame buildings after the explosions; (iii) the APM is only applicable to evaluate the collapse resistance of MI RC frames under the external explosion of cargo van bomb (1814 kg of equivalent TNT) or even less charge weight.

Experimental study of the dynamic responses of surrounding jointed rock masses and adjacent underground openings and induced ground vibrations subjected to underground explosion

The shock wave generated after underground blasting might lead to severe catastrophe or irreparable destruction of adjoining underground and ground structures. To investigate the dynamic response of rock masses and adjacent underground openings and induced ground vibrations subjected to underground blasting, a sequence of laboratory tests was implemented with explosive charges and cement mortar blocks. The results show that not only the charge loading density but also the joint orientation affect the ground peak particle velocity (PPV) in a significant way, as well as the first peak strain at the neighbouring opening and in the surrounding rock masses. The first peak strain of the rock masses has a rising tendency with increasing charge loading density or decreasing scaled distance. The PPV on the ground clearly increases with increasing charge loading density. The first peak strain of the rock masses and ground PPV are dominated by the wave path, which is determined by the relative locations of the explosion source, measuring point and joints. The principal frequency of ground vibrations shows an increasing trend with increasing joint orientation, while the charge loading density slightly impacts the principal frequency. These research findings could enhance the comprehension of blasting wave propagation through jointed rock masses and contribute to the stability evaluation of aboveground and underground structures subjected to underground explosions.

An Heuristic Prediction Method for Managing Environmental Blast Noise Impacts

The aim of this work is to manage adverse environmental impacts from long-range blast noise. The work was carried out as part of ongoing research at the DNV Spadeadam Testing and Research site (STaR). STaR carries out crucial major hazards work including improving safety concerns within industry decarbonization sectors and government agencies. The site performs a variety of explosives testing, resulting in environmental blast noise at off-site residential locations. The site is surrounded by complex topography, with terrain featuring range-dependent ground impedance and thermal properties which in turn effects the local meteorology. While accurately modelling blast wave propagation through such environments using traditional computational methods is a computationally expensive task, the required complex and rapidly varying meteorological data are not adequately available. To address this deficiency, a data-driven heuristic method is proposed for the prediction of blast noise levels at several sensitive receivers ranging from 4-14km. The model is formed from a preliminary dataset of off-site blast noise measurements, correlated with a multivariate array of available meteorological data. A principal component analysis is used to determine the atmospheric features which are most influential to sound propagation, and predict the likely range of peak sound pressure levels expected. It is concluded that useful predictions over time scales from an hour to a number of days can be obtained for managing environmental blast noise impacts, and that further measurements of blast noise, along with further correlations with measured atmospheric conditions, could improve the performance of the model.

Prediction of Peak Pressure by Blast Wave Propagation Between Buildings Using a Conditional 3D Convolutional Neural Network

To predict the damage resulting from an explosion in the middle of a city, where buildings are concentrated, the peak pressure reaching the walls of the buildings or in between buildings should be accurately and rapidly calculated. However, predicting peak pressure between buildings is known to be very difficult because of the diffraction and reflection of blast waves, which have generally been analyzed by numerical analysis methods. However, numerical analysis is not suitable in a military operation environment which requires rapid analysis, because it takes considerable time and resources. This study proposes a deep neural network that quickly and accurately predicts the peak pressure caused by the propagation of blast waves, for the effective analysis of weapon effectiveness and damage in urban environments. The proposed deep learning model is based on a 3-dimensional convolutional neural network (3D CNN) model that processes the spatial information of explosion and measurement in the 3D spaces using 3D kernels. To predict the peak pressure between buildings separated by an arbitrary distance using a single model, we also propose using conditional convolution, which modulates the prediction output according to the building distance. The proposed models were trained with a dataset constructed through finite element analysis with various building distances, explosion locations, and explosive weights. The experiment with a fixed building distance showed that the relative error of the proposed 3D CNN is less than 7%, which is 2.5 times more accurate than a simple multi-layer perceptron (MLP) model. For unseen building layouts, the conditional 3D convolution showed 3.6 times lower error than the MLP model, demonstrating the effectiveness of the conditional convolution for prediction in arbitrary building layouts. Most importantly, the proposed deep learning models took less than one minute per prediction, which is significantly faster than finite element analysis, which takes 6 to 8 hours to analyze a single simulation case.

Effect of Horizontal Curve on the Response of Road Tunnels under Internal Explosion

Internal explosion in a tunnel is a complex loading phenomenon where the tunnel lining is subjected to not only direct impact of explosion but also loading due to multiple reflection of blast waves which could be of magnitude higher than that of incident blast wave. This kind of loading is complex in nature and difficult to predict using simple analysis tools. Further, it poses a serious threat to its structural integrity. Studies have been conducted in the past to understand the behaviour of tunnel under internal explosion. However, they have been focused on straight tunnels ignoring the convex and concave shapes introduced due to horizontal and vertical curves. Shape of the target surface has significant effect on the characteristics of blast wave. This study investigates the effect of horizontal curves on the damage behaviour of tunnel lining due to internal explosion. A series of numerical simulation are performed on box-shaped tunnel with varying curvature radius and the results are compared with that of straight tunnel adopting Multi-Material Arbitrary Lagrangian-Eulerian (MM-ALE) method using LS-DYNA®. Explosive and air are modeled using ALE formulation, whereas, tunnel and soil are modeled using Lagrangian formulation. Further, Jones-Wilkins-Lee equation of state is used to model the explosion. Damage to the tunnel lining is measured in terms of peak particle velocity (PPV) and von-Mises stress. It is observed that walls of curved tunnels undergo more PPV compared with straight tunnel wherein concave wall show the highest PPV. Propagation of blast wave along the tunnel length is significantly affected due to the introduction of curvature resulting in change in reflection patterns. This further leads to variation in stress contours on tunnel lining with higher concentration of stress in curved tunnels than in straight tunnel.

Solution of Unsteady Flow Equations for Nanoscale Heat and Mass Transfer in Diverse Applications

Abstract A new innovative stable time-dependent compressible flow solution over the order of nanoseconds is provided here for wide-ranging critically important challenging applications. Specifically, a solution of the highly complex unsteady high speed oscillating compressible flow field inside a cylindrical tube, closed at one end with a piston oscillating at very high resonant frequency at the other end, has been obtained numerically, assuming one-dimensional, viscous, and heat-conducting flow, by solving the appropriate fluid dynamic and energy equations. An iterative implicit finite difference scheme is employed to obtain the solution. The scheme permits arbitrary boundary conditions at the piston and the end wall and allows assumptions for transport properties. In successfully predicting the time-dependent results/data, an innovative simple but stable solution of unsteady fluid dynamic and energy equations is provided here for wide ranging research, design, development, analysis, and industrial applications in solving a variety of complex fluid flow heat transfer problems. The method is directly applicable to pulsed or pulsating flow and wave motion thermal energy transport, fluid-structure interaction heat transfer enhancement, nanoscale heat and mass transfer, diverse range of advanced fluidics, biofluidics/bio-engineering, and fluidic pyrotechnic initiation devices. It can further be easily extended to cover muzzle blasts and high energy nuclear explosion blast wave propagations in one-dimensional and/or radial spherical coordinates with or without including energy generation/addition terms. No other solution exists for such applications.

Rethinking “BLEVE explosion” after liquid hydrogen storage tank rupture in a fire

The underlying physical mechanisms leading to the generation of blast waves after liquid hydrogen (LH2) storage tank rupture in a fire are not yet fully understood. This makes it difficult to develop predictive models and validate them against a very limited number of experiments. This study aims at the development of a CFD model able to predict maximum pressure in the blast wave after the LH2 storage tank rupture in a fire. The performed critical review of previous works and the thorough numerical analysis of BMW experiments (LH2 storage pressure in the range 2.0–11.3 bar abs) allowed us to conclude that the maximum pressure in the blast wave is generated by gaseous phase starting shock enhanced by combustion reaction of hydrogen at the contact surface with heated by the shock air. The boiling liquid expanding vapour explosion (BLEVE) pressure peak follows the gaseous phase blast and is smaller in amplitude. The CFD model validated recently against high-pressure hydrogen storage tank rupture in fire experiments is essentially updated in this study to account for cryogenic conditions of LH2 storage. The simulation results provided insight into the blast wave and combustion dynamics, demonstrating that combustion at the contact surface contributes significantly to the generated blast wave, increasing the overpressure at 3 m from the tank up to 5 times. The developed CFD model can be used as a contemporary tool for hydrogen safety engineering, e.g. for assessment of hazard distances from LH2 storage.

Experimental and numerical investigation on the dynamic response and damage of large-scale multi-box structure under internal blast loading

Internal blast is different from external or air blast for the reason of internal blast load is much more complicated and more destructive to target structures. The present work presents a large-scale experiment on multiple steel box structure under confined blast loading. A multi-box structure specimen with a dimension of 7.5 m × 2.9 m × 2.2 m was designed and field blast test with 1.782 kg TNT detonated inside this model was carried out. The damage features and dynamic response of the specimen were analyzed. The plates near the explosive suffer from strong impact and result in some fragments with high velocity which are destructive to other structural members. Meanwhile, the dynamic response processes were recorded by using the high-speed photography system. The response process of the whole model can be divided into two different stages, namely, localized damage response stage and integral vibration stage. In addition, numerical model considering both double-sided and single-sided fillet welding of this large-scale experiment were built, the dynamic response and the propagation of internal blast wave were analyzed. The numerical studies show that, to achieve a good consistency with the experiment, the failure strain for double-sided and single-sided fillet welding should be set to 0.1 and 0.08 respectively for such large-scale structure under explosive load. Finally, several suggestions for the design of multi-box structure are put forward based on the experimental and numerical investigations.

Performance assessment of seismically-designed steel moment-resisting structures against numerically-simulated blast wave propagation

Performance assessment of seismically-designed steel moment-resisting structures against numerically-simulated blast wave propagation

Propagation and intensity of blast wave from hydrogen pipe rupture due to internal detonation

The coupled fluid-structure-rupture model was developed to study the propagation and intensity of blast wave from hydrogen pipe rupture due to internal detonation. The dynamic rupture of pipe and propagation of blast wave were well coupled together in every timestep during the simulation. The numerical model was validated with experiments in terms of both typical rupture profiles and blast overpressures. Results reveal that crack branching of pipe can dramatically increase the rupture opening rate which controls the intensity and shape of the resultant blast wave. Due to the process of crack initiation and extension, the blast wave out of the pipe first forms and then is strengthened by the subsequent compression waves. This makes the maximum peak overpressure appears at a certain standoff distance above the rupture. Despite consuming some percentages of energy, the dynamic rupture of pipe generally presents positive effects (up to 2–3 times) on the blast wave intensity along the jetting direction due to the convergence effect of rupture opening on the release of internal high-pressure gas. Finally, through defining normalized overpressure and impulse based on the same hydrogen detonation in open spaces, the quantitative influences of pipe rupture on the blast wave intensity in cases of different detonation pressures and standoff distances are clarified.

A simplified approach to modelling blasts in computational fluid dynamics (CFD)

This paper presents a time-efficient numerical approach to modelling high explosive (HE) blastwave propagation using Computational Fluid Dynamics (CFD). One of the main issues of using conventional CFD modelling in high explosive simulations is the ability to accurately define the initial blastwave properties that arise from the ignition and consequent explosion. Specialised codes often employ Jones-Wilkins-Lee (JWL) or similar equation of state (EOS) to simulate blasts. However, most available CFD codes are limited in terms of EOS modelling. They are restrictive to the Ideal Gas Law (IGL) for compressible flows, which is generally unsuitable for blast simulations. To this end, this paper presents a numerical approach to simulate blastwave propagation for any generic CFD code using the IGL EOS. A new method known as the Input Cavity Method (ICM) is defined where input conditions of the high explosives are given in the form of pressure, velocity and temperature time-history curves. These time history curves are input at a certain distance from the centre of the charge. It is shown that the ICM numerical method can accurately predict over-pressure and impulse time history at measured locations for the incident, reflective and complex multiple reflection scenarios with high numerical accuracy compared to experimental measurements. The ICM is compared to the Pressure Bubble Method (PBM), a common approach to replicating initial conditions for a high explosive in Finite Volume modelling. It is shown that the ICM outperforms the PBM on multiple fronts, such as peak values and overall overpressure curve shape. Finally, the paper also presents the importance of choosing an appropriate solver between the Pressure Based Solver (PBS) and Density-Based Solver (DBS) and provides the advantages and disadvantages of either choice. In general, it is shown that the PBS can resolve and capture the interactions of blastwaves to a higher degree of resolution than the DBS. This is achieved at a much higher computational cost, showing that the DBS is much preferred for quick turnarounds.

The blast mitigation mechanism of a single water droplet layer and improvement of the blast mitigation effect using multilayers in a confined geometry

The blast mitigation mechanism of a water droplet layer was numerically studied, considering convective heat transfer and quasi-steady drag. The propagation of a one-dimensional blast wave in a shock tube was modeled, leading to momentum and energy transfer between the water droplets and the air. Convective heat transfer absorbed part of the energy, thereby directly mitigating the blast wave. Although the quasi-steady drag transferred less energy than the convective heat transfer, it exhibited greater blast mitigation. Thus, a parametric study using characteristic values and describing the water droplet layer was conducted to examine the blast mitigation mechanisms involved in the quasi-steady drag, aside from the energy absorption effect. It was determined that each time the shock wave reached the air/water droplet interface, the quasi-steady drag divided the wave into transmitted and reflected waves. Because the one-dimensional blast wave helped to carry some of the energy, the division reduced the energy carried by the incident blast wave, resulting in its mitigation. Finally, the blast mitigation effect of multilayers was compared with that of a single layer. The result showed that increasing the number of layers synergistically improved the blast mitigation effect by dividing the shock wave multiple times.

Study on the liquefaction characteristics of saturated sands by millisecond delay blasting

The liquefaction in saturated sands under blast loading is an important research topic in geotechnical engineering. The effect of blast loading on the liquefaction characteristics of saturated sands was studied through a large-scale millisecond delay blasting (MDB) liquefaction field test. Based on the field test, a numerical model was established by the LS-DYNA finite element program to study the propagation of blast waves and the effects of explosive mass, scaled distance, and blast delay on the liquefaction characteristics of saturated sands. The results show that there was a significant sand boiling phenomenon in saturated sands under blast loading, and high values of the excess pore water pressure ratio were observed at monitoring points during the field test. The numerical simulation results show that the scaled distance and the blast delay significantly affected the excess pore water pressure. While the blast delay increased from 110 ms to 330 ms, the excess pore water pressure of the central area can increase by more than 18%. Based on the field and numerical tests, an empirical equation is established that can take into account both the scaled distance and blast delay, which provides a theoretical basis for future large-scale liquefaction sites by MDB.

Nonlinear transient response of elastoplastic sandwich beam in underwater blast and the fluid-structure interaction

This work focuses on a new theory on the transient response of elastoplastic sandwich beam in underwater blast, and two fully coupled fluid-structure interaction (FSI) models are proposed, to gain insight into the propagation and dissipation of underwater blast wave, and the optimal design for sandwich structure with excellent underwater blast resistance. Based on the nonlinear dynamic high-order sandwich panel theory (EHSAPT) according to the authors’ preceding work [1], the governing equation of motion is constructed and modified by integrating the rarefaction-wave-related term into the structural damping matrix. So, the underwater blast analysis is transformed into the dynamic response of sandwich structure with structural damping under the superposition of incident and reflected waves in vacuum. Furthermore, this governing equation is simplified to get the analytical solution of impulse transferred to the sandwich structure, by implementing displacement and core rigidity assumptions. Finite element simulation and two existing FSI models are used to validate the accuracy. Conclusions are drawn that, the key aspects dominating FSI mechanism and time-domain response include pressure signatures, fluid characteristics, front-face mass, core density, and core elastic modulus, and the quantitative relationships are provided. Moreover, the core elastic modulus dominates the impulse transmitted to the sandwich structure, and the core strength and strain hardening govern the pressure delivered to the supports.

High‐performance computing of 3D blasting wave propagation in underground rock cavern by using 4D‐LSM on TianHe‐3 prototype E class supercomputer

AbstractParallel computing assigns the computing model to different processors on different devices and implements it simultaneously. Accordingly, it has broad applications in the numerical simulation of geotechnical engineering and underground engineering, of which models are always large‐scale. With parallel computing, the computing time or the memory requirements will be reduced by splitting the original domain of the numerical model into many subdomains, which is thus named as the domain decomposition method. In this study, a cubic and equal volume domain decomposition strategy was utilized to realize the parallel computing on the distributed memory system of four‐dimensional lattice spring model (4D‐LSM) based on the message passing interface. With a more efficient communication strategy introduced, this study aimed at operating an one‐billion‐particle model on a supercomputer platform. The preprocessing procedure of the parallelized 4D‐LSM was restructured and the particle generation strategy suitable for the supercomputer platform was employed to minimize the time consumption in preprocessing and calculation. On this basis, numerical calculations were performed on TianHe‐3 prototype E class supercomputer at the National Supercomputer Center in Tianjin. Two field‐scale three‐dimensional blasting wave propagation models were carried out, of which the numerical results verify the computing power and the advantage of the parallelized 4D‐LSM in the simulation of large‐scale three‐dimension models. Subsequently, the time complexity and spatial complexity of 4D‐LSM and other particle discrete element methods were analyzed.

Experimental research of shaped charges with electrohydraulic effect with a view to improving blasting safety and efficiency

Ore mining in hard rocks generally includes drilling and blasting. Blasting technologies belong to the most hazardous industrial processes. One of the ways of increasing efficiency of mining is improvement of blasting technologies toward enhancing the rates and efficiency of growth in the mining industry at the reduced risk of injuries. The present-day stage of drilling and blasting in underground mining features the use of high-capacity drilling equipment and tools, introduction of novel drilling and blasting design and implementation methods and technologies, creation of effective mechanisms for application of innovations, and wide-scale adoption of energy- and resource-saving technologies. Higher safety of drilling and blasting ensues from upgrading of drilling equipment, firing devices, explosives and charge designs. The composition of an explosive and the design of a charge have an essential influence on the volume and composition of a gas-and-dust cloud induced in blasting, and on the range of dispersion of broken rock fragments. In this regard, shaped charges have demonstrated their efficiency but their wide introduction needs further studies into specification of the process parameters. This article focuses on the method of experimental research into the shaped charge effect using a science-based electrohydraulic laboratory model. The shaped charges have proved their exploitability. The mathematical formulation of the problem on the blast wave propagation in enclosing rock mass of structurally complex mineral deposits is discussed. The hydrodynamic theory of the shaped charge effect is substantiated and the process parameters are determined.