Explosion Depth Research Articles

Study of permissible dynamic load on high-pressure gas pipe laying site in connection with blasting operations during open-pit mining

The paper presents the results of a study of permissible dynamic load on high-pressure gas pipe laying site of the II category located within the mining lease boundaries, in connection with carrying out blasting operations at the open-pit mine of JSC Sukholozhsktsement. The procedure of IM UrB RAS for calculating the permissible distances from the technological explosion in the mine to the protected object (gas pipeline) depending on the explosive weight in the stage, coefficient of soil conditions and permissible velocity of seismic vibrations is presented. It is found that depending on the explosion depth in the mine and using corresponding geological data, by changing the weight in the delay stage, it is possible to completely eliminate the negative effect of explosion on pipe laying area. A calculation scheme is also proposed to determine the safe distances to high-pressure gas pipeline depending on the angle of open pit side and blasting depth.

ANALYZING THE INFLUENCE OF THE EXPLOSION DEPTH ON THE STRESS-STRAIN BEHAVIOR OF CIRCULAR TUNNEL IN SATURATED SOIL

This paper presents the effects of the explosion depth on the stress-strain behavior of circular tunnel in saturated soil with 2 approaches: experiment and numberical method (SAP2000 ver 12.0). The result of experiment and numerical methods indicate the factors on the declining of explosion energy for design the tunnel in saturated soil subjected to blast loading purpose.

Mechanical Damage and Response of a Buried Steel Pipeline Under Subsurface Explosion Load

Abstract Subsurface explosions seriously threaten the safety and reliability of buried oil and gas pipeline. In order to investigate the mechanical responses of buried steel pipeline under subsurface explosion load, a numerical model of pipeline–soil coupling under explosion load was developed. Stress, displacement, plastic deformation, and local buckling of the buried pipeline were investigated. The effects of trinitrotoluene (TNT) magnitude, pipeline diameter-thickness ratio, pipeline's buried depth, explosive depth, and explosive offset on the mechanical response of pipeline were studied. The results show that the response time of buried pipeline is very short under the explosion load. There is a dent appearing on the pipeline section toward the exploding location. Cross-sectional area of the pipeline decreases along the time during the explosion, but it gradually increases for the elastic recovery. Pipeline's deformation and total energy increase gradually with the increasing of trinitrotoluene magnitude or diameter-thickness ratio, but they decrease with the increasing of the buried depth or explosive offset. With the explosive depth increases, the pipeline's plastic deformation first increases and then decreases. The pipeline's energy curve can be used to determine the buckling state under explosion load. The empirical formulas of the maximum strain and dent rate for buried pipelines have been obtained and can be used for the pipeline safety assessment.

Long-term rail profile damage in a railway crossing: Field measurements and numerical simulations

Railway crossings are subjected to a severe load environment leading to a degradation of rail profiles due to wear and accumulated plastic deformation. This damage is the result of the high magnitudes of contact pressure and traction generated in the wheel–rail contact during each wheel transition between wing rail and crossing nose. An extensive measurement campaign has been carried out at a test site in Austria in a particularly severely loaded crossing manufactured from an explosion depth hardened (EDH) manganese steel grade. For an accumulated traffic load of 65 Mega-Gross-Tonnes (MGT), the evolution of profile degradation for 16 cross-sections along the crossing rail has been recorded on multiple occasions. The results from the measurement campaign are used to validate a previously presented multidisciplinary and iterative simulation methodology for the prediction of long-term rail damage. It is shown that the predicted rail profile degradation exceeds the measured degradation for some of the cross-sections but generally a good qualitative agreement is observed. Possible reasons for the higher predicted damage are the uncertain distribution of traffic at the test site and differences in material properties between the crossing in the field and the test specimens used for calibration of the cyclic plasticity model. The influence of the frequency of updating the rail profiles in the iterative simulation methodology, and the compromise between computational cost and the number of load cases accounted for in the applied load sequence, are addressed.

Experimental and Numerical Investigation of Reinforced Concrete Pile Subjected to Near-Field Non-Contact Underwater Explosion

High-pile wharf is an important port structure and may suffer from accidental explosions or terrorist bombing attack during the service life. The reinforced concrete (RC) pile is one of the popular vertical load-bearing piles of high-pile wharf structure. As a main load-bearing member of the high-pile wharf structure, the damage of RC pile due to underwater explosive may cause subsequently progressive collapse of the whole structure. In this paper, the dynamic response and failure mode of RC pile in high-pile wharf structure under the near-field non-contact underwater explosion are investigated using a combined experimental and numerical study. First, a typical RC pile was designed and tested for the near-field non-contact underwater explosion. The failure mode and damage of the RC pile specimen were obtained and analyzed. Second, the numerical model of the RC pile under near-field non-contact underwater explosion was established by adopting the commercial software AUTODYN, and then validated based on experimental results. It was shown that the results from numerical model and experimental test compared very well in terms of the damage pattern and lateral displacement. Furthermore, the full-scale numerical model of the RC pile for the near-field non-contact underwater explosion was developed based on the validated numerical model to investigate the damage pattern and failure mode of RC pile under varied underwater explosives. Lastly, the safety distance for the RC pile for the underwater explosion loading with consideration of different explosive mass, the explosive depth and the concrete strength was suggested. The outcome of this study presented reference for analysis, assessment and design of the type of RC pile for high-pile wharf structure subjected to near-field non-contact underwater explosion.

Study on the shock wave effect and engineering algorithm in the tunnel after structure damage under different explosion conditions

In this paper, according to dimensional analysis, the dimensionless function of the intensity of the air shock wave overpressure of the explosion in structure leaking into a tunnel is established. Forty-eight experiments were carried out focusing on some influencing factors such as explosive charge, explosive depth, ratio of reinforcement, concrete matrix strength, and existence of the structure, revealing the influence laws of explosive charge, explosive height, ratio of reinforcement and concrete matrix strength on the overpressure intensity of air shock wave. Then, engineering calculation methods for leak shock wave effect are obtained, which include the overpressure distribution of shock wave in explosive tunnel in structure, equivalent coefficient of explosive charge compared with explosion in tunnel as well as the reduction factor of shock wave with or without structure.

Study on the influence of rigid wall surface on the bubble characteristics of underwater explosion

In order to investigate the influence of rigid wall surface on the bubble characteristics of underwater explosion, the underwater explosion experiment under the boundary conditions of free surface and rigid wall surface was carried out on 2.5g cylindrical charge TNT in a 2×2×2m tank. The time history curves of shock wave and bubble pulsation were obtained by underwater pressure sensor, and the bubble pulsation process was observed by high-speed photography. The experimental results show that compared with the free surface underwater explosion, the shock wave peak pressure and the bubble pulse peak pressure in rigid wall surface underwater explosion are increased, and a large cavitation area appeared at the junction of rigid wall and water surface. After the bubbles contacted the rigid wall surface, the bubble morphology changed significantly, the first bubble pulsation period and the maximum radius of bubble expansion became larger. After the first bubble pulsation, the bubble partially collapsed and split into two parts, bubbles continued to pulsate in the direction of the rigid wall and the bottom of the water. Finally, combined with the experimental data of rigid wall surface at different explosion depths, the relationship between the first bubble pulsation period, the maximum bubble expansion radius and the explosion depth of 2.5gTNT under rigid wall conditions is given.

Prolonged simulation of near-free surface underwater explosion based on Eulerian finite element method

In the area of naval architecture and ocean engineering, the research about the underwater explosion problem is of great significance. To achieve prolonged simulation of near-free surface underwater explosion, the underwater explosion transient numerical model is established in this paper based on compressible Eulerian finite element method (EFEM). Compared with Geers–Hunter formula, EFEM is availably validated by simulating the free-field underwater explosion case. Then, the bubble pulsation and flow field dynamic characteristics of the cases with different underwater explosive depth are compared in this work. Lastly, the height of the water hump and the pressure of flow flied are analyzed quantitatively through the simulation results.

Blast-induced damage and evaluation method of concrete gravity dam subjected to near-field underwater explosion

Bomb attacks from terrorists have become potential risks to important infrastructures, most of which were built without considering their vulnerability to such events. This paper focuses on the blast-induced damage to concrete gravity dams subjected to near-field underwater explosions. Different from direct damage mode analysis, a novel vibration-based damage evaluation method is proposed to illustrate the damage state of a dam after an explosion. To this end, a three-dimensional fluid-solid coupling numerical model in LS-DYNA is proposed for simulating the shock wave propagation and its interaction with dam structures, in which the explosive, air, and water are meshed by an arbitrary Lagrangian-Eulerian (ALE) formulation, while the dam and its foundation are meshed by the Lagrange formulation. Then, the structural responses and damage characteristics of the dam are investigated under various explosion scenarios considering changes in explosive charge, standoff distance and detonation depth. On this basis, the optimized vibration characteristics, including peak velocity summation (PVS) and mean frequency (MF), are adopted to evaluate the vulnerability of concrete gravity dams subjected to underwater explosions, which is better than the traditional damage evaluation method based solely on the peak particle velocity (PPV). The PVS-MF spectrum criterion proposed in this study is feasible to evaluate the damage state of concrete gravity dams after underwater explosions, and the results can be used in the blast-resistance design of similar hydraulic engineering.

Tsunamis generated by subaqueous volcanic explosions in Taal Caldera Lake, Philippines

Volcanic subaqueous explosions can generate hazardous tsunamis, especially in lakes. In this paper, we simulate different scenarios of subaqueous explosions and related tsunamis in Taal Caldera Lake (Luzon, Philippines). Taal volcano is one of the most active volcanoes in Southeast Asia, and eruptive processes are mostly explosive. We test different energies of explosions at eight different explosion sites in the lake. The initial water surface displacement (ƞ0) generated by the explosion is estimated as a function of explosion energy at a given depth. We estimate the tsunami travel times, maximum wave heights, and wave periods at the shoreline. This type of hazard is typically neglected and our work has important implications for hazard assessment around Taal Lake. Due to fast propagation of tsunamis in the lake (waves typically crossing the lake in less than 10 min), there is only a short time available for issuing a warning. For ƞ0 ≤ 50 m, wave heights at the shoreline are less than 2 m with a non-dispersive numerical model, and less than 0.5 m with a dispersive model, whatever the explosion depth and location. Powerful explosions with ƞ0 > > 100 m generate wave heights greater than 2 m all around the lake and local peaks higher than 10 m.

Experimental study on dynamic buckling of submerged grid-stiffened cylindrical shells under intermediate-velocity impact

Dynamic buckling prediction of submerged structures under impact loads is a challenging problem for both theoretical and numerical approaches, and the experimental data is very limited. In the present paper, dynamic buckling of grid-stiffened cylindrical shells submerged in a large opening pond at a depth of 5 m and subjected to radial intermediate-velocity impact was experimentally investigated. In order to increase load durations under the condition of fixed peak pressure, explosive depth and standoff distance, airbags composed of O2 and C2H2 were used and exploded underwater to generate impact load. Amplitudes and durations of shock waves and pulsating bubbles were characterized by using pressure transducers. Measurements of hoop and axial strains reveal that global buckling of skin and stiffeners of the grid-stiffened cylindrical shell occurred under bubble pulsation loads, which features mutation and separation of strains and a sudden change in the vibration period of the stiffened shell with a small increment of impulse. 6 half waves and 1 half wave are observed along the circumferential and axial directions of the shell, respectively. Larger bubble pulse impulse, greater deformation and vibration of the shell under larger impact are the main reasons for global dynamic buckling of the grid-stiffened cylindrical shell.

Blast Parameter Optimization Study Based on a Blast Crater Experiment

The blasting quality and the rock volume blasted directly affect the cost of mines. A small charge‐forward blast crater experiment was conducted to study the relationships between the rock volume blasted, the explosive unit consumption, the bulk yield, and the depth ratio. The results showed that the rational resistant line or explosive charge depth should be 0.86 times the optimal resistant line. Based on theoretical analysis of the large spacing of the holes and the small resistance line, the uniform design method was used to conduct the lateral blasting crater tests. The relationship equations among the blasting parameters, the blasting volume, and the bulk yield were obtained by regression analysis. The results illustrated that the rock volume blasted was negatively correlated with the bulk yield. The contribution rates of the resistance lines and the spacing of the holes to the blasting volume regression were 32.4% and 13.9%, respectively, and to the bulk yield regression were 65.0% and 0.256%. The impact of the resistance line on the blasting volume and the bulk yield was more significant than that of the spacing of the holes. The blasting effect of the rectangular blast hole arrangement was better than that of the square pattern. The blasting technology of large hole spacing and a small resistance line could achieve a better blasting effect while ensuring a higher rock volume blasted. The economical and reasonable blasting parameters were determined as the hole spacing of a=8.5 m and the resistance line width of W=5.5 m, with the rock volume blasted of 413.1 m3 and the bulk rate of 0.218%. This method provides an effective method for optimization of the blasting parameters and has important guiding significance for efficient and economical mining.

Analysis of long-range sound propagation in West Pacific Ocean

A long-range sound propagation experiment was conducted in the West Pacific Ocean in July 2013. LFM (Linear frequency-modulated) signals with frequency band of 260–360 Hz were transmitted by a transducer hung on a floating ship during the experiment and received by a horizontal line array towed by another ship sailing away from the transducer. Signals were received at the ranges 34–220 km, 612–635 km and 926–1029 km. In addition, explosives signals with explosive depth of 1000 m were received by a vertical line array and the maximum propagation range was 943 km. In this paper, experimental data on the long-range propagation are analyzed, and transmission losses versus range in convergence-zone propagation and those versus range and depth in deep-sound-channel propagation are obtained. The PE model and ray theory are used to analyze and explain the properties of the long-range pulse sound propagation observed in this experiment. It is shown that RAM is adequate for estimating the transmission loss. It is shown that in convergence-zone propagation water depth rarely influences the transmission loss when it is greater than the surface conjugate depth but contributes significantly to the transmission loss when the situation is the opposite, however the effect of water depth on transmission loss in deep-sound-channel propagation can be ignored. What’s more, the transmission loss increases when the distance between the receiver and the channel axis increases.

Experimental study of the water jet induced by underwater electrical discharge in a narrow rectangular tube

This paper reports an experimental investigation on the effects of explosion depth and tube width on the water jet induced by an underwater electrical discharge in a narrow rectangular tube. The water jet formation and bubble structure were evaluated from the images recorded by a high-speed video camera. Two typical patterns of jet formation and four general patterns of bubble implosion were observed, depending on the explosion depth and tube width. The velocity of the water jet was calculated from the recorded images. The jet velocity was observed to depend on not only the explosion depth and energy, but also on the tube width. We proposed an empirical formula defining the water jet velocity in the tube as a function of the tube width and explosion depth and energy.

On the infrasound detected from the 2013 and 2016 DPRK's underground nuclear tests

AbstractThe underground nuclear tests by the Democratic People's Republic of Korea (DPRK) generated atmospheric infrasound both in 2013 and 2016. Clear detections were made in the Russian Federation (I45RU) and Japan (I30JP) in 2013 at stations from the International Monitoring System. Both tropospheric and stratospheric refractions arrived at the stations. In 2016, only a weak return was potentially observed at I45RU. Data analysis and propagation modeling show that the noise level at the stations and the stratospheric circumpolar vortex were different in 2016 compared to 2013. As the seismic magnitude of the 2013 and 2016 nuclear test explosions was comparable, we hypothesize that the 2016 test occurred at least 1.5 times deeper. In such a case, less seismic energy would couple through the lithosphere‐atmosphere interface, leading to less observable infrasound. Since explosion depth is difficult to estimate from seismic data alone, this motivates a synergy between seismics and infrasonics.

含Pb(N<sub>3</sub>)<sub>2</sub>系列起爆药废水的处理

介绍了含Pb(N3)2系列起爆药废水的组成、处理的工艺原理和方法以及处理的步骤和工艺流程。实践证明：采用销爆、转化、萃取、深度除铅对含Pb(N3)2系列起爆药废水进行综合处理的工艺合理、操作安全，处理后的废水符合国家规定排放标准。 The composing, processing principle and way of treatment, processing steps and technological pro- cessing are introduced in this paper. The wastewater containing Pb(N3)2 series initiating explosive deals with the synthetic approach including explosion elimination, conversion, extraction and depth removal of lead. The practice has proved that the method of this paper has reasonable pro- cess, operation safety and the wastewater after treatment meets the standards for charging.

Circum-crater variability of deposits from discrete, laterally and vertically migrating volcanic explosions: Experimental evidence and field implications

Circumferential variation in sorting, thickness, granulometry, and componentry of tephra ring deposits can result from instabilities in the eruptive jet and interactions with the confining crater. Jet instabilities result in fingers of high particle concentrations that form deposits radiating away from a crater, referred to as rays. Two major types of rayed deposits are described from subsurface explosion experiments: (1) symmetrical rayed deposits with an axisymmetric ejecta blanket, which result from vertically directed eruptive jets and (2) zones of rays that extend out from sectors of a crater, with an asymmetrical proximal ejecta skirt, that result from inclined jets. Variations within each group are also associated with variations in the explosion depth relative to the energy of the explosion. Although the surface morphology of rays is likely to be lost in natural tephra rings due to overlapping deposits of numerous explosions, rayed deposits are expected to be preserved in cross section as lenses of relatively coarse and poorly sorted material compared to surrounding deposits. Asymmetrical deposits of inclined jets are anticipated to be particularly distinctive. The experimental facies associations indicate that these deposits would be easily distinguished, given sufficient exposure, from other heterogeneities caused by wind influence, collapse of the crater rim, or the influence of topography on density currents. These experimental results can also be used to further the discussion of deposits from inclined jets from other explosion scenarios, such as Vulcanian blasts and hydrothermal explosions. The experimental rayed deposits described here indicate that the classic interpretation of clast concentration zones in tephra ring deposits must be reevaluated.

Scaling multiblast craters: General approach and application to volcanic craters

AbstractMost volcanic explosions leave a crater in the surface around the center of the explosions. Such craters differ from products of single events like meteorite impacts or those produced by military testing because they typically result from multiple, rather than single, explosions. Here we analyze the evolution of experimental craters that were created by several detonations of chemical explosives in layered aggregates. An empirical relationship for the scaled crater radius as a function of scaled explosion depth for single blasts in flat test beds is derived from experimental data, which differs from existing relations and has better applicability for deep blasts. A method to calculate an effective explosion depth for nonflat topography (e.g., for explosions below existing craters) is derived, showing how multiblast crater sizes differ from the single‐blast case: Sizes of natural caters (radii and volumes) are not characteristic of the number of explosions, nor therefore of the total acting energy, that formed a crater. Also, the crater size is not simply related to the largest explosion in a sequence but depends upon that explosion and the energy of that single blast and on the cumulative energy of all blasts that formed a crater. The two energies can be combined to form an effective number of explosions that is characteristic for the crater evolution. The multiblast crater size evolution has implications on the estimates of volcanic eruption energies, indicating that it is not correct to estimate explosion energy from crater size using previously published relationships that were derived for single‐blast cases.

Determining the source characteristics of explosions near the Earth's surface

AbstractWe present a method to determine source characteristics of explosions near the Earth's surface. The technique accounts for the reduction in amplitudes as the explosion depth approaches the free surface and less energy is coupled into the ground. We apply the method to the Humming Roadrunner series of shallow explosions in New Mexico where the yields and depths are known. Knowledge of the material properties is needed for both source coupling/excitation and the free surface effect. Although there is the expected trade‐off between depth and yield, the estimated yields are close to the known values when the depth is constrained to the free surface. We then apply the method to a regionally recorded explosion in Syria. We estimate an explosive yield less than the 60 t claimed by sources in the open press. The modifications to the method allow us to apply the technique to new classes of events.

Types and mechanisms of strombolian explosions: characterization of a gas-dominated explosion at Stromboli

Textural and chemical analyses of bombs quenched directly from a normal explosion at Stromboli volcano (Italy) were integrated with coincident seismic, acoustic, and thermal data. The data set defines a new gas-dominated type of “strombolian” eruption, named type 0. These events are characterized by high-velocity emission (150–250 m s−1) of a few relatively small, juvenile particles, with entrained non-juvenile clasts that previously fell back into the vent to be re-erupted. For the studied event, the explosion depth was more than 250 m deep, and the particles showed little residence time in the shallow system. Slug ascent velocities over the final 20–35 m of magma-filled conduit, and the low viscosity of the resident magma, are all consistent with simple bubble burst in a “clean” conduit. This conduit type and eruption style likely fit popular slug ascent and burst models used to explain “strombolian” eruptions. In contrast, the ballistic-dominated type of explosions (type 1) are associated with larger proportions of stagnant material in the shallow system magma mix. We argue that the additional volume of this stagnant material pushes the free surface upward. Because of the larger volume of material available for entrainment into a type 1 slug burst, which has to fragment through a thick cap of degassed material, type 1 events tend to be rich in particles. In contrast, the less spectacular, gas-rich (type 0) events have little material to entrain, thus being poor in lapilli and bombs.