Explosion Resistance Research Articles

Enhanced formation of magnesium silica hydrates (M-S-H) using sodium metasilicate and caustic magnesia in magnesia castables

Abstract Magnesium-silica-hydrates (M-S-H) is a promising binder for magnesia castables due to its bonding strength and progressive dehydration behavior over a wide temperature range during the heating-up stage. Sodium metasilicate and caustic magnesia were used to form M-S-H in magnesia castables. The results showed that M-S-H was remarkably produced in the caustic magnesia-microsilica slurries containing sodium metasilicate with increasing pH value, which activated the hydrolysis of microsilica into silicic ions and enhanced the M-S-H formation. When 0.3 wt% caustic magnesia and 0.05 wt% sodium metasilicate as additives were incorporated into magnesia castables, the cold crushing strength and cold modulus of rupture of castables after drying at 110 °C reached the maximum value of 68.3 MPa, which corresponded to ~ 40% improvement in comparison with those of caustic magnesia and sodium metasilicate-free magnesia castables. Besides, the enhanced formation of M-S-H bonding system contributed to a better explosion resistance of magnesia castables.

Effect of size on methane-air mixture explosions and explosion suppression in spherical vessels connected with pipes

An experimental apparatus was set up to demonstrate the effect of size on methane-air mixture explosions in spherical vessels connected with pipes. Two spherical vessels and pipes were used to constitute different-sized linked vessels. In this paper, gas explosions and explosion suppression were studied. Under the condition of the vessel size being changed and the pipe length not being changed, the maximum explosion pressure is almost constant, while the maximum explosion pressure rising rate decreases with increasing vessel diameter. A larger vessel with a longer pipe will lead to a safer explosion environment. When a large spherical vessel is connected, there exists a certain length to keep the pipe terminus safer. However, for a small spherical vessel, the pipe terminus becomes more dangerous with increasing pipe length. When wire-mesh is added between the pipe and spherical vessel, the maximum explosion rising rate in a small vessel decreases much more than without wire-mesh. However, for a large vessel, the change of the maximum explosion rising rate is not clear. Generally speaking, wire-mesh has a positive effect on explosion suppression in a vessel; however, in a pipe terminus, it has only a positive influence when a small spherical vessel is connected. The conclusions provide an important reference for the safety design of explosion venting and explosion resistance.

Self-flowing high-alumina phosphate-bonded refractory castables

Phosphate refractories have a great potential to be applied in petrochemical industries as they present suitable properties at the temperature range used in fluid catalytic cracking units. This study addresses the development of high-alumina self-flowing castables bonded with H3PO4 solution (48wt% concentration) or a mixture of phosphoric acid and monoaluminum phosphate (MAP) solutions, using MgO as a setting agent. Two polyphosphates (Budit 3H and 6H) and citric acid were evaluated as dispersant additives for these castables. The compositions were characterized by measuring their free-flow and temperature evolution over time, working and setting times, cold and hot mechanical strengths, drying behavior and explosion resistance, eroded volume and thermal shock resistance. The results indicated that high flowability (free flow >100%) could be attained when adding the selected polyphosphates to the mixtures, whereas citric acid acted mainly as a retarder agent for the castables’ setting. Moreover, free-flowing compositions with a suitable working time were obtained when combining H3PO4+MAP solutions as main binders. The thermo-mechanical tests pointed out that the most promising designed refractory (containing mixture of H3PO4+MAP and 0.5wt% of Budit 3H) presented similar or even a better performance than a benchmark commercial vibratable product used in petrochemical units.

Effect of one obstacle on methane–air explosion in linked vessels

The effect of one obstacle on the explosion intensity of a methane–air mixture in connected vessels was studied. The experimental results suggested that the blockage ratio and the position of obstacles played a great role in this intensity. The obstacles could increase the reaction speed. When the blockage ratio reaches a certain value, the disturbance effect on the flame is at its highest, and the turbulence intensity and explosion intensity are at their strongest. If the obstacle’s blockage ratio is greater than or less than this value, the explosion intensity is weaker. If the obstacles are closer to the initiating container, the combustion pressure will rise earlier both in the initiating container and in the connecting pipe. However, the effect of the obstacle position on the peak combustion pressure is limited. The conclusions provided an important reference for the safety design of explosion venting and explosion resistance.

Study on an engineering measure to improve internal explosion resistance capacity of segmental tunnel lining structures

With the increase of terrorist bombing attacks on subway systems, few research results could be traced on the internal explosion capacity of segmental tunnel linings. This paper presented some full-scale test results of segmental tunnel linings under internal explosions, and the deformation and failure patterns of segmental tunnel lining were analyzed and outlined, wherein the key factors and positions that dominate the damage of a segmental lining were figured out. Then based on a conceptual idea, attempts were made, by adding flexible damping cushions on the joints, to relieve the damage degree of contact area of bolts. At last, numerical simulations were performed and it was shown that, the localized failures of joint areas of tunnel segments could be relieved effectively after introduction of this measure, so the internal explosion resistance performance of segmental lining structures could be optimized and hence improved.

Numerical simulation of internal gaseous explosion loading in large-scale cylindrical tanks with fixed roof

As a common and important type of thin-walled structure, large-scale cylindrical tanks are widely used for the storage of hazardous petrochemicals. The detonation of those flammable substances generates destructive explosive shock waves in an instant, which may cause serious damage to tanks and even bring economic losses and casualties. Accurate and rational determination of explosion loading on tanks is the foundation for structure damage analysis and explosion resistance design of tanks. For simulating explosion flow field in closed containers, a CFD model was established based on conservation equations, realizable k-ε turbulence models, EDC (Eddy-Dissipation-Concept) combustion models and SIMPLEC (Semi-Implicit Method for Pressure-Linked Equations with Consistent) algorithms. Compared with experimental data reported in existing literatures, the effectiveness and accuracy of the numerical methods and the CFD model were validated. And then on this basis, a series of numerical simulations have been carried out to ascertain the magnitude and distribution of internal explosion loading on tanks, taking into account the influences of tank capacity, H/D (height-to-diameter ratio), roof form, flammable gas species and height of underlying oil level. These indicate that maximum explosion loading on tanks increases along with increase of tank capacity, H/D and reactivity of flammable gas in general. And increases of the underlying oil volume and inert gas content in tanks are conducive to lowering the value of explosion loading. Moreover, tanks having dome roofs and rounded arc junctions show a better anti-explosion performance from the aspect of structural design.

Experimentally Evaluated Explosion Resistance and Performance of Destruction Unit in Multiple Detonation of Ammunition

Experimentally Evaluated Explosion Resistance and Performance of Destruction Unit in Multiple Detonation of Ammunition

Simulation of the Reactive Powder Concrete (RPC) Behavior Reinforcing with Resistant Fiber Subjected to Blast Load

In research or experimental works related to blast loads, the amount of explosion material and distance of explosion point are very important. So, in this paper has been attempted to present a parametric study of the reactive powder concrete subjected to blast load. The effect of the different amount of TNT adopted the literature, distance of explosion point from RPC slab and also the location of explosion charge (horizontal and vertical coordinates form the center of specimens) has been investigated. In order to the analytical simulation of RPC behavior against blast and also the accuracy of acquired results, at first using ABAQUS software, a RPC slab studied in the literature has been verified. The obtained results are showed that the simulated model of RPC is match with literature one. In the next stage, a case study of the effect of explosion charge and also the distance of explosion point from RPC and NSC (normal strength concrete) slabs have been examined, and the results have been compared. It’s noted that the NSC slab is supposed to be a reinforced concrete, whereas 2% volume of special short steel fibers were used in the RPC specimen. The acquired results have been showed that the RPC have better blast explosion resistance than reinforced normal strength concrete.

Expediency of application of explosion-relief constructions to ensure explosion resistance of production buildings

The article presents a model of economic evaluation and selection of explosion-relief constructions (ERC), as well as determination of explosion protection efficiency of buildings and structures provided on a stage of construction. It has been shown that definition of economic efficiency of ERС is the evaluation of its application for buildings with remote or automatically controlled production. It has been determined that an important role in design of explosive industrial facilities is played by selection of the economically feasible and effective materials for ERC. When selecting materials it is necessary to consider probability and yield of explosions. Necessity to create the methods allow considering such probability has been revealed.

Blast impact behaviour of concrete with different fibre reinforcement

The paper summarizes the results of the development of special concrete intended for the explosion resistance applications, with the emphasis on minimal secondary fragments formation at the explosion. The fine-grained concrete matrix has been reinforced by various types of short dispersed fibers (metallic, mineral and polymer) of different sizes and by their combination and the effect of the fibre reinforcement on the physico-mechanical properties and blast resistance was observed. The concrete prism specimens have been subjected to the determination of mechanical parameters (compressive and flexural strength at quasi-static load). The blast tests were conducted on the slab specimens prepared from selected mixtures. The material characteristics and explosion test data have been used for numerical investigation, which defined the optimal wall composition and dimensions of the concrete element which should resist the explosion defined by type, size, weight and placement of the blast. In the next step the test elements resistance was verified by real explosion test.

Characteristics of gas explosion flow fields in complex pipelines

The explosion flow field in five straight pipes with different diameters and one bending pipe selected from a domestic coal mine are studied by the method of numerical simulation. And the results show that, both in the straight and bending pipes, the pressure wave and velocity wave are accelerated by the rising of reaction rate. As the explosion progressed, with the temperature reaching approximately 3000K, only one pressure wave and one reaction rate wave were observed, while several velocity waves were found. The larger diameter presented the highest relative pressure as well as the largest velocity increase and subsequent decrease inside the tube. The bent pipes caused both turbulence and kinetic energy to increase, resulting in the acceleration of the reaction rate. The burning time was 7.4% shorter than the burning time observed for the straight pipe. Based on these results, designing one explosion resistance device, and in the practical engineering applications, it was to be proved to meet the security requirements fully.

Dynamic Analysis on Explosion Resistance Performance of Reinforced Concrete Wall

Based on the finite element software ABAQUS, this paper deals with numerical simulation to dynamic response of reinforced concrete wall under blast loading. Study shows that the explosion resistance performance of the wall with four edges fixed or with two opposite edges fixed are better than that of the wall one edge fixed and another opposite edge simply supported. The greater the explosion impulse, the bigger the maximum displacement of the wall. When reinforcement ratio of the wall increases, the explosion resistance performance of the wall will be improved. At the same time, reasonable reinforcement and external conditions should be made sure. Keywords: Blast Loading, Numerical Simulation, Shear Wall, Dynamic Response

The Effect of the Type of Reinforcement on the Mechanical Parameters of Concrete and on its Explosion Resistance

The paper summarizes the up to now results of the development of special concrete intended for the explosion resistance applications, the emphasis is put also on minimal secondary fragments formation at the explosion. The fine-grained concrete matrix has been reinforced by various types of dispersed fibers (metallic, mineral and polymer) of different sizes and by their combination, while the same volume content of fibres has been kept. The concrete prism samples have been subjected to the determination of mechanical parameters (compressive and flexural strength, modulus of elasticity). The concrete test elements of the same sizes as commercial products have been made and their explosion resistance was tested. The material characteristics and explosion test data have been used for modeling the adequate wall thickness of the concrete element which should resist the explosion defined by type, size, weight and placement of the blast. In the next step the test elements has been reinforced by additional outer layer of non-metallic tissue and subjected to explosion tests.

A Review of Numerical Study on Explosion and Shock Wave Resistance of Metal Foam Material

The goal of this research is to understand the status quo and trend of research on numerical simulation of explosion and shock wave resistance of metal foam material. Methods of modelling metal foam material and numerical algorithms of explosion and shock, as well as the current advances in two aspects have been briefly reviewed. Some problems existing in numerical simualtion of explosion and shock wave resistance of metal foam material have also been pointed out. Conclusions of this research will be of benefit to study explosion and shock wave resistance of metal foam material using numerical approach farther.

Gas pipeline explosion resistance technology

Based on the features and requirements of gas drainage system, an optimized explosion resistance technology is done after a comprehensive analysis and research about the triple IR (Infrared Ray) flame detection technology, explosion resistance valve technology and explosion resistance control technology. An intelligent PLC (Programmable Logic Controller) resistance control system is designed which can cut off the gas branch quickly and accurately, and the controller have automatic pressure maintaining function, valve rotation limit function, remote and local control interlock function. The reliability and rationality of explosion resistance technology is verified by gas pipeline explosion propagation and resistance simulation test. Overall response time of explosion resistance system is less than 100ms, and the spread of fire in gas pipeline can be prevented effectively.

Numerical Simulation of Polyurethane Strengthened Perforated Masonry Walls under Blast Loading

In order to investigate the explosion resistance performance of perforated masonry walls strengthened with polyurethane, nine numerical models with different layer number and different strip width of polyurethane are established in this paper. Deformation drawings and time history curves of displacement of the numerical models are comparatively analyzed. It is found that there are two failure modes, global failure and local failure, of strengthened masonry walls and the differences of failure patterns are significant between various types of strengthening method.

Study on Explosion Resistance Performance of Injected Fluid Structure

Based on simplified theory model of injected fluid structure, select steel plate as maintenance structure and water as test equipment of liquid production, do field tests of explosion and analyze explosion resistance performance of structure. The results show that the injected fluid structure has good explosion resistance performance and that its cutting-wave ratio reaches to about 85%. It provides experimental basis for explosion resistance performance of injected fluid structure in the explosion load.

Explosion Resistance Investigation into Sandwich Structure of Steel Fiber Reinforced Concrete Support Plate

Abstract. In order to avoid the damage of precision guided weapons on target, a steel fiber reinforced concrete sandwich structure with different types of support was proposed. The failure characteristics of penetration plate, steel fiber reinforced concrete plate and support beam were studied by contact explosion test. The results showed that the using of steel fiber sheet sandwich structure could increase a resistance level for the project with the same thickness of the protective layer. The failure mode of steel fiber reinforced concrete sandwich structure under partial blast loading was still the local damage mode, the strength and thickness of steel fiber laminate material, height and spacing of support beam were the main factors to control the effect of wave attenuation in steel fiber reinforced concrete sandwich structure, if some measures to prevent vibration on steel fiber sheet or under-surface of vault would enhance the resistance of structure.

Experimental study on scaling the explosion resistance of a one-way square reinforced concrete slab under a close-in blast loading

Full-scale experiments involving actual geometries and charges are complicated and costly in terms of both preparation and measurements. Thus, scaled-down experiments are highly desirable. The present work aims to address the scaling of the dynamic response of one-way square reinforced concrete slabs subjected to close-in blast loadings. To achieve this objective, six slabs of two groups were tested under real blast loads. Three slabs with different scale-down factors were investigated using two scaled distances. Two major damage levels were observed, namely, spallation damage from a few cracks, and moderate spallation damage. The test results show that the macrostructure damage and fracture in the experiments are almost similar. However, the local damage in concrete slabs with larger-scale factors is slightly reduced compared with that of slabs with smaller-scale factors. Two empirical equations are proposed based on the results to correct the results when scaling up from the model to the prototype.

A Double Thick Beam FEM with Explosion Resistance Dynamics Analysis Based on Spline Wavelets in Underground Structure

Isoparametric B-spline wavelet functions can provide excellent approximation for smooth functions. In this paper, the response of composite laminated plate subjected to explosions is analyzed by using a double thick beam FEM mode based on the spline wavelet function. This mode, which can be considered in the distribution of normal stress and transverse shear stress simultaneously, is very important in the analysis of thick plate or blast-damage mechanism. The mode in analyzing underground structure and earth medium respond has the advantage of high precision and fast constringency and is easy to establish a element displacement function. The comparison between simulative and experimental results shows the effectiveness and precision of this method.