TNT Charge Research Articles

Analysis of Wind Turbine Towers subjected to Blast Loading

The research work in this paper mainly focuses on the dynamic simulation of a High strength steel wind turbine tower subjected to blast loading in increasing order, conducted by using ABAQUS. The analysis of the wind turbine tower evaluates the response and performance of the structure when subjected to blast load levels in the form of TNT charges ranging from 500 kgs to 2000 kgs applied at the base and at the top of the tower respectively. The study focuses mainly on the key parameters such as Von Mises stress, displacement, and reaction forces in which the results indicate that the High strength steel wind turbine tower passes the Von Mises stress limit up to a blast load of 1500 kgs at the base but fails under higher loads of 1750 kgs and 2000 kgs respectively where stresses of the wind turbine tower exceeds the tensile strength of the material. Moreover, at the top of the tower, the structure fails at a low charge of 500 kgs demonstrating its vulnerability to the blast load. Displacement of the wind turbine tower surpasses its recommended limit for TNT charges beyond 1500 kgs at the base with a maximum displacement of 129.49 mm at 2000 kgs. The maximum reaction force recorded was 2890 KN at a TNT charge of 1750 kgs. The study concludes by revealing the findings of the limitations of High-strength steel wind turbine towers under extreme blast conditions and throws spotlight on the need for structural reinforcement or alternative designs and hybrid towers for the wind turbine for improved performance and use in high-risk environmental zones.

Numerical modelling of an impact resistance analysis of EN C45 steel pipe buried beneath the ground surface loaded with a detonation wave generated by an explosion of a cubic TNT charge

Numerical modelling of an impact resistance analysis of EN C45 steel pipe buried beneath the ground surface loaded with a detonation wave generated by an explosion of a cubic TNT charge

Advancing blast fragmentation simulation of RC slabs: A graph neural network approach

Accurate prediction of blast-induced fragmentation in reinforced concrete (RC) structures is pivotal for structural debris hazard assessment in an explosion event. This assessment is essential for designing effective measures for protection of people and structure in the vicinity. While conventional computational techniques are proficient, they are computationally very demanding and may not be readily adaptable in practical applications. This study proposes a novel approach, the Fragment Graph Network (FGN), a specialized variant of graph neural networks (GNNs), to simulate complex interactions between macro-level particles of RC structures subjected to close-in blast loads. The RC structure is discretised into particles, with the model predicting structural responses and fragmentation based on states of these particles. Utilizing an autoregressive prediction mechanism, our model can accurately simulate spatiotemporal responses of RC slabs against blast loads. The efficacy of the model was tested on a dataset consisting of 149 simulated cases, encompassing around 180,000 states each, covering a wide range of blasting scenarios and structural design parameters including TNT charge weight, standoff distance, slab dimension, concrete strength, and reinforcement ratio and layout. Notably, the proposed model delivered accurate predictions, achieving relative errors under 10% and R2 values exceeding 0.93 for both standard and extrapolated test scenarios as compared to the SPH simulations. Remarkably, our model dramatically outpaced traditional numerical approaches, reducing simulation times from hours to minutes on CPUs and seconds on GPUs. This pioneering effort paves the way for efficient and accurate simulations of RC blast fragmentations, offering a rapid alternative to standard numerical approaches.

Improved deep neural network for predicting structural response of stiffened cylindrical shells to far-field underwater explosion

This paper is focused on the application of the machine learning for predicting structural response of ring stiffened cylindrical shells subjected to far-field underwater explosion. Three deep neural network (DNN) models are combined to predict the progressive plastic deformation behaviour of stiffened cylindrical shells subjected to the shock wave produced by a TNT charge. In the DNN regression models, the input variables include the charge mass, stand-off distance, detonation depth, cylindrical shell thickness, stiffener web and flange. These three DNN models composed of multi hidden layers are trained based on the data collection originated from a series of simulations performed by the ABAQUS finite element solver. Grid search is introduced to the hyperparameter tuning for deep learning, improving the prediction performance of machine learning methods. The DNN models are compared to the models trained using another three methods: multiple linear regression, decision tree and k-nearest neighbour. An improved Adam optimisation algorithm is used to increase the accuracy of prediction. The challenges encountered during the predictions are discussed to provide a more comprehensive insight into the advantage of the proposed DNN models. The DNN regression models can well predict the permanent plastic deformation and strain of stiffened cylindrical shells.

Experimental and numerical study of corrugated steel-plain concrete composite structures under contact explosions

This paper investigates the dynamic response and blast resistance of corrugated steel-plain concrete (CSPC) composite structures subjected to contact blast. A series of explosive tests were conducted to investigate the acceleration, deformation, and damage patterns of CSPC plates under varying blast loads and arrangements of shear connectors, and these findings were compared with reinforced concrete (RC) plates. The results suggested that CSPC plates exhibited superior ductility and blast resistance, and effectively mitigated concrete collapse. The CSPC slab primarily underwent elastic deformation when the TNT charge was small, with the rebound deformation of the concrete and steel plates acting as a significant mode of energy dissipation. As for larger TNT charges, the maximum deformation of the plate progressively increased, especially when exceeding 0.3 kg, the deformation rebound ratio decreased significantly, and the plastic deformation increased. For further increased explosive loads, the concrete and steel plates exhibited a pronounced strain rate effect with a slowed growth rate of deformation. By examining different configurations of shear connectors, it was discovered that the adhesive strength between concrete and steel plates was closely related to the energy dissipation mode, and the elastic recovery capability and deformation resistance of the CSPC structure significantly deteriorated when the shear connectors were shorter, sparser or thinner. A numerical model based on LS-DYNA was designed to further analyze the blast resistance characteristics of CSPC plates. An engineering collapse coefficient Kz was established to predict the failure level of the CSPC plates. This paper provides useful insights for the optimal design and damage assessment of CSPC composite structures.

Dynamic response of hybrid corrugated/foam sandwich structure under combined loading of blast and fragments

A hybrid sandwich panel with lightweight core composed of corrugated core and metallic foam were designed. The dynamic responses of this hybrid sandwich panels were numerically investigated under combined loading of blast and fragments by LS-DYNA software. To simulate this loading condition, the TNT charge was used to drive prefabricated fragments. The developed numerical approach was validated by using the existing experimental results. The effects of foam layer location, foam density, back plate configuration and stand-off distance on the dynamic response were systematically analyzed. The results indicate that the hybrid sandwich panels with corrugated and foam separation demonstrate higher protective capability. Compared with the foam-filled corrugated sandwich panels, the energy absorption is increased by up to 16.3%. Increasing the foam density can enhance the impact resistance of the structure under combined loading of blast and fragments. The back plate with composite plate has better anti-fragmentation ability than the steel plate.

Finite element analysis of concrete slab exposed to high velocity pressure wave – simplified vs. smoothed-particle hydrodynamics (SPH) method

Many structures are required to sustain the structural resistance also under extreme loading conditions, for example impacts of high-velocity objects (airplane crash into nuclear power plant), impacts of projectiles (defence structures), or while exposed to high velocity pressure wave caused e.g. by explosion of various chemicals in industry, nature gas, or also conventional weapons. Numerical analyses of these phenomena are feasible while utilizing explicit approach of the finite element method (FEM), available in commercially accessible software LS-Dyna. In order to predict the behaviour of the structure properly, advanced nonlinear material models are required to be considered, which are often mathematically described by numerous input parameters. Several approaches to model the exposure to blast load exist, from simplified, where the blast wave is considered as timedependent pressure based on empirical equations, to more advanced ones, where the propagation of the pressure wave itself through the surrounding environment is being modelled Arbitrary Lagrangian Eulerian, (ALE method), or so called smoothed-particle hydrodynamics (SPH) method, which might be used to model the blast itself. In this paper, FEM analyses of a simply supported concrete slab with basalt fibre reinforced polymer (BFRP) bars exposed to close range explosion of TNT charge are presented. 3D numerical models are analysed utilizing explicit solver of LS-Dyna. Karagozian and Case (K&C) nonlinear material model for concrete is used, which is suitable when high strain rates are present in the quasi brittle materials. Two variants of the blast loads modelling are compared. The simplified empirical approach, which is less demanding on computational power, and feasible for utilization in case of simple structure geometry, and more demanding method using SPH method to model the TNT detonation and interaction with the exposed concrete slab. The results of these numerical analyses are compared with experimental data based on available literature, and properly discussed.

Investigations on geopolymer-based seawater sea-sand high performance concrete slabs reinforced with basalt FRP bars under direct contact explosions

Adopting locally available raw materials like seawater and sea-sand in coastal areas and oceanic islands has facilitated meeting the demands of marine engineering. However, these raw materials contain corrosive elements that could threaten the steel reinforcement in concrete structures, thus non-corrosive fibre-reinforced polymer (FRP) bars are proposed. In the present study, the geopolymer-based seawater sea-sand high performance concrete (G-SHPC) slab reinforced with basalt FRP bars was designed to preliminarily evaluate its dynamic behaviour under contact explosions. Tests were conducted on three large-sized slabs with different TNT charge weights, including 0.8 kg, 1.6 kg and 2.2 kg. To complement the experimental investigation, a numerical simulation was then performed in ANSYS-DYNA. A Continuous Surface Cap (CSC) model was developed to accommodate the unique characteristics of G-SHPC. Two different blast modelling methods, including the Arbitrary Lagrangian-Eulerian (ALE) algorithm and a hybrid Finite-Element (FE) and Smooth Particle Hydrodynamics (SPH) algorithm, were examined to faithfully reproduce the contact explosion phenomena. The structural models considered the bond-slip behaviour, and three bond-slip models were compared. The numerical results obtained through the ALE algorithm and the beam-in-solid bond-slip model exhibited fair agreement with the test results, with a maximum error of less than 6.3%. A parametric study was further conducted to establish the damage identification diagram. Formulas based on empirical data were formulated to anticipate the damage degrees of G-SHPC slabs exposed to contact explosions.

Explosion damage effects of aviation kerosene storage tank under strong ignition

In order to study the blast damage effects of aviation kerosene storage tanks, the out-field explosion experiments of 8 m³ fixed-roof tanks were carried out. The fragments, shock wave and fireball thermal radiation of the tank in the presence of bottom oil, half oil and full oil, as well as empty tank, were investigated under internal explosion by various TNT charge contents (1.8 kg, 3.5 kg and 6.2 kg). The results showed that the tank roof was the only fragment produced, and the damage forms could be divided into three types. The increase of TNT charge content and oil volume enlarged the deformation of the tank, while the hole ratio presented a trend of increase first and then decrease. The Hr, max and Vmax values positively increased as increasing the TNT charge content and oil volume (from empty to half oil), but decreased in full oil. The Pmax values had a progressive increase with the increment of TNT charge content, but not the case with the increase in oil volumes. The development of fireball was divided into three stages: tank roof ‘towed’ flame, jet flow flame tumbling and rising, and jet flow flame extinguishing. The Dmax and Hf, max values both increased as increasing TNT charge content and oil volumes. The oscillation phenomenon of fireball temperature was observed in the cooling process. The average temperature of fireball surface was positively correlated with TNT charge content, and negatively correlated with oil volumes.

Dynamic Response and Damage Characteristics of Large Reinforced Concrete Slabs under Explosion

To investigate the damage characteristics of reinforced concrete (RC) buildings during explosive incidents, a large RC slab (4 m × 5 m × 0.15 m) was meticulously designed, fabricated, and subjected to explosion experiments, which were complemented by comprehensive numerical simulations. The dynamic response parameters of the RC slabs under 0.5–1 kg TNT explosions were tested using polyvinylidene fluoride (PVDF) pressure sensors, displacement sensors, and acceleration sensors. The damage morphologies under 5–40 kg TNT explosions were investigated using ANSYS/LS–DYNA 17.0 software. The results show that, with an increase in TNT charge, the RC slab gradually showed minor damage (5 kg), moderate damage (10–20 kg), heavy damage (25 kg), and complete destruction (30–40 kg). For the 20 kg TNT explosion condition, a 1020 mm × 760 mm explosion crater appeared on the top surface, which was in agreement with the 934 mm × 906 mm explosion crater obtained from the simulation. Based on the results, suitable P–I (pressure–impulse) curves for the 4 m × 5 m × 0.15 m RC slab were established. The results can provide a reference for damage assessments of large-sized buildings during explosion accidents.

Effect of load details of the successive explosions on the blast behaviors of reinforced concrete beams

SummaryThe objective of this study was to study the effect of load details of successive explosions on the blast behaviors of reinforced concrete (RC) beams. First, the effect of the successive loading of two identical explosions was discussed by considering the influences of standoff distance, charge mass on the failure states, and structural responses (displacement and support reaction force). And keeping the total TNT charge mass of 1 kg unchanged, the effect of loading numbers was investigated by loading two 0.5 kg TNT successively and a single 1 kg TNT on RC beams, respectively. Besides, the successive loading of two different explosions was also considered by investigating the effects of loading sequences and the first explosion induced pre‐damage on the ultimate accumulated damage of RC beams. At last, based on the reaction force and displacement responses, a nonlinear relationship between the dynamic residual load‐carrying capacity and the accumulated residual displacement was obtained to assess the damage states of the tested beams. The results show that the local failure range along the beam span direction (length of peeling‐off and length of spallation) caused by the first blast load did not apparently increase when the damaged beams were subjected to another blast load. With the increase in explosion numbers, depth of compressive crushing increases gradually. At the same stand‐off distance (from 0.25 to 0.45 m), due to the damage accumulation effect, successive loading of two 0.5 kg TNT can trigger more severe local failure but smaller accumulated residual deflection to beams than the single loading of a 1 kg TNT. Besides, when two different blast loads are loaded on tested beams, the loading sequence of the larger one first and then the smaller one (1 kg TNT/0.5 kg TNT at h = 0.45 m) can trigger larger damage to beams than the opposite loading sequence (0.5 kg TNT/1 kg TNT at h = 0.45 m). And for the beams subjected to a smaller blast load first and then a larger one, a stiffer behavior may be triggered by the second blast load on the beam after the first loading of the smaller blast load due to the residual strain in longitudinal reinforcement. Furthermore, based on the nonlinear relationship between residual load‐carrying capacity and residual displacement, the accumulated damage of RC beams was divided into mainly four phases.

Field Test on the Effects of Explosively Generated Plasma on Aerial Depth Bombs Plab- 250-120

Abstract In order to gain access to the booster and main explosive charges of PLAB-250-120 aerial depth bombs, i.e. the TNT charge and the TGAF-5M explosive composition of TNT, hexogen (RDX), aluminum powder and phlegmatizing agent respectively, Explosively Generated Plasma (EGP) devices were used to perforate their steel bodies. EGP devices were made in two versions. The first used a cylindrical TNT charge, while the second used a cylindrical charge shaped from SEMTEX PW4 plastic explosive. The explosive charges were supported by waveguides with conical cavities tapering towards the bomb. The structural components of the EGP devices, i.e. the bodies housing the explosive charges and the waveguides, were made of plastic by 3D printing. The effects of the EGP on the bomb were studied depending on the explosive material used, its mass and the distance of the EGP device waveguide from the side surface of the bomb. Simultaneous firing of an array of two EGP devices inserted with SEMTEX PW4 explosive, contacted their waveguides with the bomb, resulted in its detonation, while simultaneous firing of the analogous array of the same type two EGP devices inserted with SEMTEX PW4 explosive, with their waveguides at a distance of 10 mm from the bomb, resulted in perforation of two circular through-holes in the bomb body. Firing single EGP device inserted with TNT, being in contact through its waveguide with the body of the bomb, resulted in local rupture of the bomb body with crushing the bomb explosive charges, so allowing easy access to bomb explosive charges and sampling them.

Nonlinear fitting based energetic material explosive shock wave pressure action evaluation model

There are many varieties of new developed energetic materials with different capabilities of shock wave pressure action. In order to effectively evaluate the explosive damage power of diverse energetic materials and to make the evaluation model universal, the TNT is used as the basic material, and the evaluation model of the explosive pressure action of energetic materials is established in this paper based on the nonlinear fitting method. Explosion tests of TNT with different charge quantities are carried out under the same test conditions, and the shock wave surface reflection pressure data at different proportional distances are obtained. The evaluation model between the peak pressure of the TNT shock wave and the proportional distances is constructed based on the explosion similarity ratio formula using the nonlinear fitting function. The prediction accuracy of the established model is verified by the typical TNT charge test, and the proposed model is applied to evaluate the explosive pressure effect of energetic materials. Experimental results show that the predication accuracy of the evaluation model for evaluating the explosion shock wave pressure action of energetic materials based on the nonlinear fitting method is higher than 86.5067%, which can meet the requirements of the engineering applications.

Experimental and Numerical Study on the Residual Axial Capacity of RC Bridge Piers after Contact Explosion

Bridge piers damaged by accidental or deliberate explosions lose a portion of their axial carrying capacity, which can induce partial and/or complete collapse of the entire bridge structure. With the aim of evaluating blast-damage and establishing blast-resistant design approaches for bridge piers, the dynamic behaviors and residual axial-load-bearing capacities (ALC) of RC piers subjected to contact explosions were studied experimentally and numerically. First, five circular cross-sectional 1/2-scale RC piers, with a height of 3 m and diameter of 450 mm, were fabricated. A field contact-explosion test on three pier specimens was conducted using TNT charge weights of 0.5, 1.0, and 2.0 kg. Then, these three postblast plus another two intact RC piers were transported to the laboratory to experimentally examine the axial bearing capacities using a hydraulic testing machine. The test data obtained included the incident overpressure–time histories and quantitative postblast damage profiles of the piers, and full curves for the axial force-displacement. Second, corresponding high-fidelity finite-element (FE) models of both the contact explosion and the succeeding axial compression tests were established. The refined numerical simulations were performed by adopting the fluid–structure interaction, multimaterial arbitrary–Lagrangian–Eulerian, and erosion algorithms implemented in the FE program LS-DYNA. The material model and the FE analysis approach were comprehensively verified by comparing the numerical simulated results with the test data. A series of numerical simulations were also conducted on seismically designed prototype bridge piers in order to examine the parametric influences on the damage mode and residual ALC, and the corresponding damage index of the piers. Finally, based on the parametric study, several blast-resistant design suggestions are proposed for prototype RC bridge piers against contact explosions.

Anti-explosion performance analysis of marine interdiction system based on ALE method

As a security protection system, the marine interdiction system can be set up outside the port to provide security protection for the ships and facilities there as well as to prevent explosions and ship collisions. This paper uses the Arbitrary Lagrangian Euler (ALE) method in ANSYS LS/DYNA to simulate a blast for an interdiction system close to the water’s surface. The simulated shock wave overpressure is extracted and fitted, and when compared with the empirical formula, it is discovered that the trend and value are in good agreement. In the case of controlled calculation scale, closer to the real situation and only consider the explosion transient effect, analysis of the dynamic reaction of the interdiction system under various operating situations to test its anti-explosion performance would help to confirm the validity of the proportional burst distance as a criterion for near-water explosion damage. The safe distance for a 500 kg TNT charge is 4.62 m, and the safe distance for a 1500 kg TNT charge is 6.37 m, when the proportional burst distance reaches 0.5, some of the cable tension reaches the breaking tension level at this moment, and foam floating balls appear to fail for some elements, but the system as a whole is still in a safe state. The research will also provide support for the optimization of the interdiction system and also provide support for the optimization and development of the marine interdiction system.

Dynamic analysis of buried pipeline with and without barrier system subjected to underground detonation

Failure of pipe networks due to blast loads resulting from terrorist attacks or construction facilities, may cause economic loss, environmental pollution, source of firing or even it may lead to a disaster. The present work develops a closed-form solution of buried pipe with barrier system subjected to subsurface detonation. The solution is derived based on the concept of double-beam system. Euler Bernoulli’s beams are used to simulate the buried pipe and the barrier system. Soil is idealized as viscoelastic foundation along with shear interaction between discrete Winkler springs (advanced soil model). The finite Sine-Fourier transform is employed to solve the coupled partial differential equations. The solution is validated with past studies. A parametric study is conducted to investigate the influence of TNT charge weight, pipe material, damping ratio and TNT offset on the response of buried pipe with and without barrier system. Further a statistical analysis is carried out to get the significant soil and pipe input parameters. It is perceived that peak pipe displacements for both the cases (with and without barrier) are increases with increasing the weight of TNT charge and decreases with increasing the damping ratio and TNT offset. The deformation of pipe also varies with pipe material. Pipe safety against blast loads can be ensured by providing suitable barrier layer. The present study can be utilized in preliminary design stage as an alternative to expensive numerical analysis or field study.

Dynamic response prediction of prototype from scale-down model for I-core sandwich panels subjected to internal explosion

Cabin scale-down model experiments are an effective approach to investigate the dynamic response of I-core sandwich panels subjected to internal explosion. However, it is difficult to guarantee the complete geometrical similarity in terms of plate thickness for I-core sandwich panels between the scale-down model and prototype due to manufacturing process restriction and thickness specifications of commercially available plates. To resolve the above issue, a new and more reasonable dynamic response prediction method with high accuracy for prototype based on scale-down model test was proposed in the present work. The feasibility and accuracy of proposed prediction method were theoretically, experimentally, and numerically verified. The effects of TNT charge mass, correction method of TNT charge mass, and quasi-static pressure load were investigated. Results show that the proposed prediction method from the energy point of view has high accuracy and good feasibility when the plate thickness of scale-down model distorts. In the proposed approach, the TNT charge mass is corrected through specific impulse correction. Higher accuracy is gained by using the proposed prediction method in the case of internal explosion with large TNT charge mass. Directly correcting the TNT charge mass on the basis of geometrical similarity still underestimates the dynamic response of incomplete scale-down model when plate thickness distorts. It is not reasonable to ignore the effect of quasi-static pressure load, because the specific impulse of quasi-static pressure load is much larger than that of shock wave load. This work can provide practicable and accurate application guidance for the design of internal explosion scale-down model experiments for I-core sandwich panels.

Dynamic behavior of UHPC-FST under close-in explosions with large charge weight

Ultra-high performance concrete filled steel tube (UHPC-FST) pier columns have great potential to apply in the bridge engineering due to the excellent structural and constructional performance, which are under the risk of car bomb attacks with close-in distance. Based on the field explosion test and numerical simulation, this study aims to examine the dynamic behavior of UHPC-FST specimens under close-in explosion with large charge weight. Firstly, the field explosion test was performed on five 1/4 scaled UHPC-FST specimens with TNT charge weight of 25 kg at scaled distances of 0.10–0.17 m/kg1/3, where the influences of standoff distance and burst height were assessed. It shows that the UHPC-FST possesses excellent blast-resistance since the specimens could maintain integrity under intensive blast loadings. Moreover, the different dynamic behaviors of UHPC-FST specimens obtained from present and previous explosion tests under large and small charge weights were also compared. Secondly, to further conduct the corresponding numerical simulation, the parameters of the Karagozian & Case Concrete (KCC) model were comprehensively calibrated for UHPC, and the finite element (FE) models of the field explosion test on UHPC-FST specimens were established by using the commercial software LS-DYNA. Finally, by comparing the damage mode and global deflection of UHPC-FST specimens between the test and simulation results, the calibrated KCC model parameters and the established FE model were fully verified. The present work could provide helpful references for designing and evaluating the blast-resistance of UHPC-FST.

Analysis on the Vulnerability of a Tunnel Entrance under Internal Explosion.

Tunnels play an essential role in the transportation network. Tunnel entrances are usually buried at a shallow depth. In the event of an internal explosion, the blast pressure will cause severe damage or even collapse of the tunnel entrance, paralyzing the traffic system. Therefore, an accurate assessment of the damage level of tunnel entrances under internal blast loading can provide effective assistance for the anti-blast design of tunnels, post-disaster emergency response, and economic damage assessment. In this paper, four tunnel entrance specimens were designed and fabricated with a scale ratio of 1/5.5, and a series of field blast tests were carried out to examine the damage pattern of the tunnel entrances under internal explosion. Subsequently, static loading tests were conducted to obtain the maximum bearing capacity of the intact specimen and residual bearing capacities of the post-blast specimens. After that, an explicit non-linear analysis was carried out and a numerical finite element (FE) model of the tunnel entrance under internal blast loading was established by adopting the arbitrary Lagrangian-Eulerian (ALE) method and validated based on the data obtained from the field blast and static loading tests. A probabilistic vulnerability analysis of a typical tunnel entrance subjected to stochastic internal explosions (assuming various charge weights and detonation points) was then carried out with the validated FE model. For the purpose of damage assessment, the residual bearing capacity of the tunnel entrance was taken as the damage criterion. The vulnerability curves corresponding to various damage levels were further developed based on the stochastic data from the probabilistic vulnerability analysis. When the charge weight was 200 kg, the tunnel entrance exhibited slight or moderate damage, while the tunnel entrance suffered severe or even complete damage as the charge weight increased to 1000 kg. However, the tunnel entrance's probability of complete damage was less than 10% when the TNT charge weight did not exceed 1000 kg.

Protective water curtains as wave attenuators for blast-resistant tunnels

Tunnels, as highly cost-demanding infrastructures which facilitate the transportation of people and goods, have been a target of terrorist attacks within the past few decades. The significance of the destructive impact of explosives on these structures has resulted in research on the development of blast-resistant design approaches. In this paper, water curtains are proposed as a blast-resistant system due to the established performance of water against explosives in free fields in previous studies as well as its capability to mitigate the potential incoming fire after an explosion. A parametric study was conducted for this purpose, considering the effects of curtain thickness, the distance of the curtain from the tunnel opening, and the amount of TNT charge. Accordingly, fifty-two finite element (FE) models were created in the FE package ABAQUS to investigate the performance of a water wall in a typical tunnel through the Eulerian approach to simulation. The water curtains had four different thicknesses and were located at three different distances from the reference point. TNT explosive charges were placed at the tunnel opening with four different masses. The thicker walls nearer to the tunnel opening were found to be more effective. However, the peak pressure reduction in all charges was in a desirable range of 53 to 80%. The parametric study also illustrated that the peak pressures were more sensitive to wall thickness rather than TNT charges mass and the wall distance from the explosives. We anticipate this preliminary study to be a starting point for the further development of the concept of water curtains for blast mitigation.