Amount Of Explosive Research Articles

Research on honeycomb structure explosives and double sided explosive cladding

In order to resolve the current issues about the backward method of charge and low energy efficiency of explosives, honeycomb structure explosives and double sided explosive cladding were used in the present study. Honeycomb structure explosives are used to ensure the quality of charge. Double sided explosive cladding can clad two composite plates simultaneously. Honeycomb structure explosives and double sided explosive cladding, which significantly reduce the critical thickness of stable detonation of explosives, are used to increase the energy efficiency of explosives and save the amount of explosives. Emulsion explosives with the thickness of 5mm can be stable detonation. In this paper, the experiment of double sided explosive cladding for two groups of steel of No. 45 with the thickness of 2mm to steel of Q235 with the thickness of 16mm and two groups of stainless steel with the thickness of 3mm to steel of Q235 with the thickness of 16mm were successfully investigated. Without constraints, the critical diameter of emulsion explosives is 14–16mm. Compared to the existing explosive cladding method, the consumption of explosives for steel of No. 45 to steel of Q235 and stainless steel to steel of Q235 are reduced by 83% and 77% in the case of cladding the same number of composite plates. The explosive cladding windows and collision velocity of flyer plate were calculated before experiment. It shows that the calculation prefigures exactly the explosive cladding for steel of No. 45 to steel of Q235 and stainless steel to steel of Q235.

Shock-Resistance Research of Ship Structural Subjected to Underwater Explosion

A finite element model ships, for example design test condition of the underwater explosion, selection of explosive package quantity is 1000KG TNT, the explosive location along the direction of the ship with the bow, midship and stern, the angle of attack in three exploded cross section have 90 degrees, 60 degrees, 45 degrees, 30 degrees and 0 degrees. According to the current standard to calculate the ship damage radius, critical radius and safety radius of specific values under the effect of underwater explosion, interpolation calculation and draw the envelope. Analysis shows that the vitality of ships and shock-resistance is not only related to the explosive distance, also related to the attack position.

Productivity of blast-fractured wells in liquid-rich shale gas formations

The explosive stimulation by blast-fracturing was first used in well stimulation with pronounced results in the booming Pennsylvania oil field in 1865. The advent of hydraulic fracturing in the 1950's caused explosive stimulation of oil wells to decline dramatically. Because the hydraulic fracturing process consumes a huge amount of water and imposes a threat to the ground water resources, it is highly desirable to revisit the feasibility of replacing hydraulic fracturing with blast-fracturing in the oil and gas well completion processes. This paper presents an analysis of well productivity of different types of well architectures to be completed with the blast-fracturing stimulation in liquid-rich shale gas formations.Compared to the hydraulic fracturing, blast-fracturing creates radial fractures with fracture-orientations independent of formation stress anisotropy. This eliminates the requirement of in-situ stress orientation that is necessary for designing multi-hydraulic fracturing horizontal wells. An analytical model was developed in this investigation to predict the initial productivity of vertical wells, horizontal wells, and radial-lateral drain holes. Case studies indicate a good agreement between the result given by the models and field observation. Sensitivity analyses with the analytical model indicate that the initial productivity of blast-fractured wells increases non-linearly with the number of radial fractures and fracture penetration. The benefit of increasing fracture depth levels out as the amount of explosives increases. This paper presents well completion engineers a theoretical base and useful data for revolutionizing their well completion technology in developing liquid-rich shale gas basins.

On the Proper Estimation of the Confidence Interval for the Design Formula of Blast-Induced Vibrations with Site Records

Blast-induced ground vibration has received much engineering and public attention. The vibration is often represented by the peak particle velocity (PPV) and the empirical approach is employed to describe the relationship between the PPV and the scaled distance. Different statistical methods are often used to obtain the confidence level of the prediction. With a known scaled distance, the amount of explosives in a planned blast can then be determined by a blast engineer when the PPV limit and the confidence level of the vibration magnitude are specified. This paper shows that these current approaches do not incorporate the posterior uncertainty of the fitting coefficients. In order to resolve this problem, a Bayesian method is proposed to derive the site-specific fitting coefficients based on a small amount of data collected at an early stage of a blasting project. More importantly, uncertainty of both the fitting coefficients and the design formula can be quantified. Data collected from a site formation project in Hong Kong is used to illustrate the performance of the proposed method. It is shown that the proposed method resolves the underestimation problem in one of the conventional approaches. The proposed approach can be easily conducted using spreadsheet calculation without the need for any additional tools, so it will be particularly welcome by practicing engineers.

Explosive fracturing simulation experiment for low permeability reservoirs and fractal characteristics of cracks produced

Based on the explosive fracturing simulation experiment for low permeability reservoir, growths of the cracks produced by the explosive fracturing in the samples were analyzed. And associated with fractal geometry theory, the cracks fractal characteristics were studied and the influences of explosive quantity and confining pressure on the cracks fractal dimension were analyzed. Different explosive quantities and confining pressures under which the simulation experiment was carried out were designed. After the experiment, the fractal dimension of the cracks produced by explosive fracturing in different samples was got by the box dimension calculation method. The results show that: With the increase of explosive quantity, the amount, length and width of the cracks on the surface of the sample produced by explosive fracturing simulation experiment under the same confining pressure increase. The amount and length of the cracks produced by explosive fracturing under the same explosive quantity decrease with the increase of confining pressure. Under the same confining pressure, the cracks fractal dimension increases with the increase of explosive quantity, and the relationship between them is approximately linear when the confining pressure is relatively low and approximately nonlinear when the confining pressure is relatively high. Under the same explosive quantity, the cracks fractal dimension decreases with the increase of confining pressure. It is suggested that site operation should match the explosive quantity with the confining pressure, and the charge pattern of axial coupling and radial uncoupling should be applied.

Limits of detection of explosives as determined with IMS and field asymmetric IMS vapour detectors

Performance of two handheld trace explosives detectors types: SABRE 4000 and MO-2M was compared in terms of the limits of detection determined for: trinitrotoluene, hexahydro-1,3,5-trinitro-1,3,5-triazine, pentaerythritol tetranitrate and nitroglycerin in the particle detection mode. SABRE 4000 detector is a conventional detector based on the ion mobility spectrometry (IMS) and radioactive nickel as the ionization source, whereas in the MO-2M type detector a variant of this technique, viz. the field asymmetric ion mobility spectrometry (FAIMS), and a different β emitter, tritium, as an ionization source are employed. In determining limits of detection the sampling technique was suggested which resorts to binomial distribution for the determination of the indispensable number of positive measurements required to regard a given amount of explosives detected as reliable. Lower limits of detection were achieved in the study for trinitrotoluene and hexahydro-1,3,5-trinitro-1,3,5-triazine with the MO-2M detector (10- and 100-fold, respectively) than with the SABRE detector, whereas for the remaining two substances limits of detection were identical for either detector. The results obtained were discussed in the aspect of the effect of the detector design, ionization mechanism and volatility of substance as the factors that determine the limits of detection values.

Experiment of Control Blasting with Water Jets Slotting

Use similar material and system of caustics to simulate the characteristics of fissure distribution and dynamic vacation regulations of fissure generation and expansion, whose fissure is made by plexiglass jet slotting and blasting under the condition of explosion. We have analyzed and compared the expanding length and velocity of main fissure’s point and dynamic intensity factors between the holes of ordinary blasting and water-jet slotting; and discussed the dynamic effects of slotting blasting. The study shows that, with the same explosive quantity, the fissures of common blasting hole distribute randomly around the hole with large quantity but with short fissures and the caustic spots have small diameter and distribute with fissures; while the fissures of jet slotting hole blasting are longer and distribute mainly along the fissure’s direction, the caustic spots are clear and mainly concentrate among the fissures with lager diameter. That is to say, the jet cutting blasting energy concentration can improve the effect of rock damage. The existence of jet seam has a guidance quality to rock breakage. Main fissures take place and expand from the direction of slotting seam while the distension along other directions is heavily weakened in the process.

Strengthening treatment and analysis for the left bank abutment of Jin Ping Arch Dam

AbstractThe Jin Ping arch dam foundation exhibits large differences in the stiffness between left and right bank due to a fault in the valley and unloading, relaxation and rock crushing effects in the left abutment. An extremely complex engineering problem appears by achieving mechanical balance for the dam body. To reinforce the left dam foundation concrete pads refilling faults, huge concrete piles and consolidation grouting together with grout and drainage curtains are investigated and executed. The numerical results show that these reinforcement measures for the excavated dam foundation improved significantly the rock mass deformability and its stability.A suitable excavation sequence for reinforcement tunnels and caverns is studied and the stability of these tunnels is analysed. The influence of consolidation grouting on the slope stability is investigated by varying spacing and number of active grouting holes. During the construction of the reinforcement tunnels the vibrations induced by blasting are simulated and measured. For different distances between tunnels and slope to tunnels respectively, the maximum quantity of explosives for single drives is studied.

Experimental analysis and simulation of effective factors on explosive forming of spherical vessel using prefabricated four cones vessel structures

Abstract Construction of spherical vessel in various dimensions is known as one of the frequent problems for construction and production engineers, since conventional methods of shell construction require mold and press which leads to higher costs of production. Therefore, current work has tried to investigate a new method based on explosive forming without using molds. In this technique, final shape of the shell can be achieved by explosion inside a prefabricated structure called four cones. This structure is produced from combination and welding of four truncated cones two of which are paired in each side. Initial shape of the tank is then used to transform this structure into a more complete sphere using explosives at its center. This paper aims to study the amount of explosives needed for this process in terms of vessel’s diameter and thickness. In this regard, simulation was run by LS-DYNA software and the resultant outputs were evaluated with those of experimental tests. The results shows that the required charge of forming varies exponentially with thickness.

Experimental Investigation of Aluminum Foam Lined Suppressive Shield Containment Vessels

Manufacture, transport, and storage of dangerous goods, especially energetic materials, in Canada and around the world pose serious challenges to explosives regulators and inspectors. Currently siting of manufacturing and storage facilities are in accordance with quantity-distance principles designed to mitigate effects of accidental explosions. The land requirements to satisfy these principles are imposing financial burdens on the explosives sector. This paper presents an experimental program designed to investigate the effectiveness of suppressive shield containers in reducing the blast pressure outside of the container while eliminating fragments thus reducing the distance requirement for the stored amount of explosives. Several suppressive shield panels including aluminium foam-lined panels were tested to study their effect on blast pressure and impulse. In addition computational fluid dynamics techniques were used to study suppressive shields effects on blast environment. The results show reduction of the incident peak blast pressure by 60% and the incident impulse by 58%. The aluminium foam-lined suppressive shield panels attenuated the peak incident pressure and impulse by 80%.

Experiment on Different Length/Diameter Ratio Charge Explosive Strain Wave Propagation in Rock

In order to explore the blasting effect with charged by different length/diameter ratio in rock, adopted ultra-dynamic strain testing system to test the blasting strain wave with charged by little amount of explosives and different length/diameter in the rock models. Analyzed the radial blasting strain wave signal in the medium under the conditions of coupling charging explosive loading, got the generalities and difference of the explosive strain waveform features with charged by different length/diameter ratio, and relationship of peak strain with the relative distance. The results show that peak strain was greatly affected by the change of length/diameter ratio and charge mass in the area of close blasting source, when the relative distance is more than 45, the influence is less. Made the length/diameter ratio is 20 to be the boundary, when the length/diameter ratio is greater than 20, the peak strain attenuated slowly. The explosive energy of the big length/diameter ratio is relatively decentralized to the medium, improved the energy utilization ratio of explosives. The measured results provided a new experimental basis to further understand correctly the rock blasting mechanism.

Cloud rise model for radiological dispersal devices events

As a part of the preparedness and response to possible radiological terror events, it is important to model the evolution of the radioactive cloud immediately after its formation, as a function of time, explosive quantity and local meteorological conditions. One of the major outputs of a cloud rise models is the evaluation of cloud top height, which is an essential input for most of the succeeding atmospheric dispersion models. This parameter strongly affects the radiological consequences of the event. Most of the cloud rise models used today, have been developed according to experiments were large quantities of explosives were used, within the range of hundreds of kilograms of TNT. The majority of these models, however, fail to address Radiological Dispersion Devices (RDD) events, which are typically characterized by smaller amounts of TNT. In this paper, a new, semi-empirical model that describes the vertical evolution of the cloud up to its effective height as a function of time, explosive quantity, atmospheric stability and horizontal wind speed, is presented. The database for this model is taken from five sets of experiments done in Israel during 2006–2009 under the “Green Field” (GF) project, using 0.25–100 kg of TNT.

Study and Handling on the Safety of Water Pressure Blast of Cisterns

The research deals with the issues and handling regarding the safety of complexly-structured round water pressure blast of cisterns, including calculating the safety-needed explosive quantity, explosive distribution mode, pre-treatment before the blast, safe construction and safe checking. The research specially focuses upon some safety issues and a general introduction to the safety measures to take in the project. Similar projects can also refer to it.

0402 背景を利用した爆風の可視化と爆発威力の評価(OS4 Background-Oriented Schlieren法による可視化計測,オーガナイズドセッション)

The blast wave caused by the explosion shows the refractive index which is different from that of ambience because the wave is accompanied by discontinuous density shift of the medium. Schlieren method is often used as a technique to observe the behavior of Shockwave in a fluid. However, it is difficult to apply to outdoor experiments because the method needs arrangements of some optical equipment around the subject. In this study, it was tried that the visualization of the blast wave with small amount of explosives. The metho d was a simple and convenient procedure from the digital frame images which had been taken by digital high-speed camera in some past outdoor experiments without any optical equipment. This method was a kind of subtraction of images' digital data, or PIV analysis. The power of explosion could be estimated by the visualized propagation of blast wave.

Damage of reinforced concrete columns under demolition blasting

The aim of this study was to qualitatively and quantitatively investigate the damage of RC column specimens in blasting tests, which was required to apply blasting demolition techniques to RC buildings with rather excessive reinforcement due to earthquake resistant design. In the blasting tests, the amount of explosives used and the longitudinal and shear reinforcement ratios and concrete strength of the RC column specimens were test variables. The test results revealed that the shear reinforcing bars confining the core concretes of the RC column specimens significantly affect the damage of the RC column specimens by the blasting. The analytical investigation supported that the residual resistances of the blast damaged RC column specimens can be evaluated through section analysis by considering the compressive buckling strength of the longitudinal reinforcing bars exposed by the blasting.

Soil-Structure Interaction and Failure of Cast-Iron Subway Tunnels Subjected to Medium Internal Blast Loading

The threat of terrorist attacks on subway systems using explosives has intensified considerably in recent years. Explosions inside subway tunnels may lead to the failure of subway structures and result in further socioeconomic losses. Specifically, the century-old, single-track, cast-iron subway tunnels in cities such as New York and London are very vulnerable to this type of attack. In this study, an explicit dynamic finite-element procedure was developed to carry out extensive numerical simulation to investigate the soil-structure interaction and failure of cast-iron tunnels in saturated soils subject to internal explosions using the medium amount of explosives (80 kg TNT) that might be perpetrated by terrorists. The stress path and damage mode of these tunnels, subjected to internal blast loading, were first investigated based on the simulated damage of cast-iron tunnel lining using a hardening elastoplastic model that considered shear damage. The study aims to better understand the soil-structure interaction and its relation to lining damage of cast-iron subway tunnels under internal blast and to investigate the influences of several critical parameters on lining failure, including compressibility of saturated soil, brittleness of lining materials, specific impulse of blast, and strength of the soil-lining interface. The study found that ground-tunnel interaction was one of the governing factors that determined the damage of tunnel lining under medium internal blast loading by providing the necessary confinement to resist internal blast loading and by absorbing blast energy with its plastic shear deformation. Lining damage was mainly triggered by the tensile hoop stress because of large inertia and dynamic forces in the radial direction of the tunnel, and it may exhibit a progressive pattern in the vibration phase. Soil compression significantly influenced the damage of the tunnel under internal blast loading. The damage was more severe with compressible saturated ground.

Blast Resistance of Double-Layered Reinforced Concrete Slabs Composed of Precast Thin Plates

When designing blast-resistant reinforced concrete (RC) structures, reducing spall damage due to reflected tensile stress waves is a major problem. Furthermore, for rapid construction of the blast-resistant structures against sudden terrorist bomb attacks, it is necessary to build it with precast concrete walls and reduce the weight of the precast elements by reducing their size for ease of transportation and construction.In this study, to propose an idea for rapid construction and better blast resistance of blast-resistant RC structures, double-layered RC slabs composed of precast thin plates, 50 mm thick, were fabricated and utilized for contact detonation tests. The tests were conducted under a condition that the amount of explosives and the dimensions of specimen were constant respectively, and two types of concrete, normal concrete and polyethylene fiber reinforced concrete (PEFRC), were employed as the slab materials. Our results showed that creating an air cavity between the two layers of PEFRC slab was effective in reducing spall damage, while the air space had no advantage in normal RC, under a condition that the thickness of the air space was fixed at 15 mm. Furthermore, the above difference between PEFRC and normal RC slabs was discussed, based on the numerical result on the fracture process of the air-sandwiched normal RC slab.

Damage Analysis for Steel Frames under Explosive Loads

In this paper, a series of inelastic transient analysis of steel frame structures under blast loads are numerically performed. Considering the coupling actions of detonator, gases and structure, Arbitrary Lagrangian Eulerian ALE method which is suitable for large deformation systems is applied. In order to capture the effect of explosion load on members, a rate-dependent stress–strain model is used to model the material response of the affected members. The dynamic response and the structural damage of steel frame under blast loading are investigated. The damage pattern of steel frame to blast loads is studied. The results show that the permanent deformation, local buckling, and plastification reduce the resistance of the frame. The affected members may trigger the overall stability of the frame. The damage degree is related to the amount and position of explosives, shape and resistance of the building etc. The damage of the low-story columns and beams may make the structure unstable. The load might not be large enough, the damage to the entire frame may be severe, and it may cause structure collapse.

Thermal desorption and vapor transport characteristics in an explosive trace detector

Swipe-based explosive trace detectors rely on thermal desorption to vaporize explosive particles collected on a swipe. The vaporized material is carried by air flows from the desorption unit to the inlet of the chemical analyzer, typically an ion mobility spectrometer. We have observed that the amount of explosives detected from a swipe varies with the physical location of explosives collected on the swipe. There are two issues that may contribute to this effect: inhomogeneous or insufficient heating of the swipe during desorption and low velocity air flows that inefficiently transport desorbed vapor during the instruments analysis time. To better characterize this effect, we have simulated the air movements within a generic desorption unit using commercially available computational fluid dynamics software. Simulations are three dimensional, symmetric and solved under steady, laminar flow conditions. The calculated velocity field correlates directly with experimental detector response to the high explosive RDX. Results suggest that the limiting factor in this model thermal desorption unit is the flow-field around the swipe and flow rate into the detector, rather than heat transfer to the swipe itself. Buoyancy effects due to heating dominate the flow-field and produce a vertical bulk fluid motion within the domain that opposes much of the flow drawn into the analyzer.

A Study on an Initiation Technique of Small Amount of Explosive

High explosives are useful material to generate great amount of energy in short time. Since controlling their releasing energy is hard, the use of explosive is limited to specific fields and industries. However, the reduction of the explosive powder mass uses at a time makes the handling safe. And use of explosives in a continuous producing process leads the new utility of the explosion. Based on this concept, we enclosed small mass explosives with a polyethylene sheet and initiate them by using metallic foil explosion. We have also developed the system that can generate small explosion continuously. Since it was not easy to initiate a small amount of explosive steady, we had initiated them by metallic foil explosion using a power-supply unit of capacitor bank with 2500J (20kV). In present study, we tested the initiation of a small amount of explosive using a comparatively small power-supply unit of capacitor bank with 4.5J (600V) and that of 2J (1kV) to apply to the general use. In this paper, result of experiments and the conclusions are shown. We observed the perfectness of explosion by using omnidirectional microphone. It is concluded that initiation of explosives enclosed with polyethylene sheet by small power supply unit at 2J (1kV) is possible, while the explosion was not perfect.