Specifics of Explosion-Venting Structures Providing Acceptable Indoor Explosion Loads

This article experimentally and theoretically demonstrates that the presence of blast-relief openings (windows) equipped with explosion-venting structures (EVS) allows explosive pressure to be reduced to a safe level (2–4 kPa). We provide results of model and full-scale experiments aimed at studying the influence of EVS parameters of blast-relief openings in explosion-hazardous buildings on the intensity of explosive loads. It was demonstrated that the maximum explosive-pressure value inside EVS-equipped buildings depends on the EVS start-to-open pressure, the structure’s response rate (lag), and characteristic dimension of the premises. Thus, each particular building requires individual selection of EVS parameters, which provide a safe level of excessive pressure in case of an explosive accident. This aspect, however, prevents the widespread use of EVS at explosion-hazardous sites. This article offers an modest upgrade of the explosion-venting structure that provides an indoor pressure equal to the EVS start-to-open pressure. The suggested innovation excludes the possibility of a significant increase in explosive pressure due to an EVS response delay. The efficiency of the suggested technical upgrade was proven by numerical experiments and indirectly by experimental studies aimed at exploring the physical processes associated with the opening of EVSs after an explosion accident. The use of upgraded EVSs will allow for provision of a known maximum level of the explosion load should an explosion event occur in an EVS-equipped room.

Research on the escape mechanism and influencing factors of harmful gas induced by blasting excavation in deep rock tunnel

The escape of toxic and harmful gases is a common disaster effect in tunnel engineering. Frequent drilling and blasting excavation disturbances under high in-situ stress environment will inevitably lead to cumulative damage effect on surrounding rock, which will increase the permeability coefficient of surrounding rock, increase the risk of toxic and harmful gas escape, and seriously endanger construction safety. In this paper, based on real-time monitoring data of harmful gases during blasting and excavation of Yuelongmen Tunnel on Chengdu-Lanzhou Railway, this study summarized laws and distribution characteristics of harmful gas escape intensified by the blasting excavation, and the effectiveness of shotcreting and grouting for water blocking to inhibit gas escape is verified. Then, taking water-containing and gas-containing voids as carriers, considering the influence of different in-situ stress, explosion load and void parameters (including void pressure, void diameter and distance between void and tunnel), to carry out research on the escape mechanism of water-soluble (H 2 S) and insoluble (CH 4 ) toxic and harmful gases under the coupling effect of stress-seepage-damage. The relationship between the amount of harmful gas escaped and the damage degree of the surrounding rock of the tunnel is analyzed, and the functional relationship between it and the in-situ stress, explosion load and cave parameters is established. The results further demonstrate that the amount of escaped harmful gases, such as methane and H 2 S is closely related to lithology of surrounding rock, occurrence conditions of the deep rock mass, development degree of structural fractures and void parameters. The damage of surrounding rock caused by dynamic disturbance during blasting excavation is the main reason of aggravating harmful gas escape. The research results can provide a theoretical reference for preventing harmful gas from escaping in the similar engineering construction.

Dynamic Response and Parametric Studies of Elliptical Blast-Resistant Door with the Combined Structure for Large Vacuum Explosion Containers

In recent years, with the improvement of environmental protection requirements year by year and the continuous expansion of explosive working scale, higher standards have been put forward for explosive working. It is hoped that the sphere of influence of the explosion can be limited to a minimal range. The explosion vessel is driven by such demand. As the explosion vessel’s key component, studying the blast-resistant door in depth is of great significance. This paper introduces a new elliptical blast-resistant door with the combined structure (EBD), mainly welded with an elliptical panel, arc support plate, and triangle support plate. The finite element program AUTODYN was used to calculate the explosion load, and LS-DYNA was used to calculate the blast-resistant door’s dynamic response. The calculation results show that the newly proposed EBD’s blast-resistance capacity is better than that of the traditional structure. To further study the factors that affect the dynamic response of the EBD, a parametric study was carried out on the EBD, mainly analyzing the influence of the vacuum degree in the explosion vessel, the number of explosives, and the diameter ratio of the EBD. The parametric calculation results show that reducing the vacuum degree in the explosion vessel and the number of explosives during explosion working can improve the blast-resistance capacity of the EBD. Based on the analysis of the dynamic response of four kinds of EBD with different diameter ratios under 0.2 atm explosion load, the optimal diameter ratio of the EBD is given.

Effect of Computational Parameters on Output Properties of Underwater Explosion by Intelligent Numerical Simulation

The computational parameters are of great influence on underwater explosion load. A one-dimensional wedge model is established to analyze the influence of boundary condition (BC), water domain and mesh density on the numerical simulation results. The results show that flowout BC is rigid boundary and transmit BC is not suitable for simulating the collapses phase of bubble pulsation. According to propagation distance of shock wave and its reflected wave, a simple method to calculate appropriate water domain is proposed. A positive correlation between mesh density (λ) and calculated peak pressure of shock wave (P m) is found. When λ tends to infinity, simulated Pm in near field is quite reliable, but the values in relatively far field are lower than empirical results.

Research on the Dynamic Response of Frame Structure under the Explosion Load of Acetylene-Air Mixture

Explosion is the act of generating huge energy in an instant and spreading rapidly around it. Due to the suddenness, fast propagation speed and high peak load of explosions, compared with other natural disasters, the damage it brings to humans is more significant and difficult to prevent. Among them, the explosion of acetylene-air mixture is the most typical explosion problem. This paper uses SAP2000 finite element software to perform a fine simulation of actual explosion events, studies the effect of the explosion of acetylene-air mixture on the frame structure column, and discusses the displacement and acceleration changes of various components. Research shows that the use of the principle of linear assumption of explosive load can effectively simulate the actual explosion situation. The structural damage and deformation caused by the explosive load have locality and weak transmission. When the peak of the explosion load is larger, the structure deformation is greater, and the impact of the explosion load on the structure is isotropic.

Strength Analysis of the Marine Weapon’s Construction

Due to the modernization of warships, it was necessary to carry out strength calculations for the newly assembled devices, for which there were no detailed technical requirements. The authors try to present and harmonize the requirements for naval military structures. The lack of experimental verification of newly built systems was indicated. Therefore the finite element method was used to determine the durability of the critical design elements. There is no explicit reference load in the literature, so the authors present a general solution to one of the worst cases. The work presents the cannon structure elements exposed to damage during the underwater explosion load, using the proposed methodology. The proposed method is sufficient to calculate individual ship cases. However, in the case of hull strength analysis, more complex algorithms should be used.

Research on Damage Characteristics of Brick Masonry under Explosion Load

As the main structural component of partition wall or load-bearing wall, brick masonry has been widely used in construction engineering. However, brick and mortar are all brittle materials prone to crack. Nowadays, fireworks, gas stoves, high-pressure vessels, and other military explosives may explode to damage nearby structures. Many explosion casualties had shown that the load-bearing capacity of brick masonry decreased dramatically and cracks or fragments appeared. Previous studies mainly focused on noncontact explosion in which shock wave is the main damage element. In fact, the response and damage effect of brick masonry wall under contact explosion are more complex, which attracts more attention now. In order to explore the damage characteristics of brick masonry under explosion load, a series of simulations and verification experiments are conducted. RHT and MO granular material models are introduced to describe the behaviour of brick and masonry, respectively, in simulation. The combination effect of front compressive wave and back tensile wave are main factors influencing the breakage of masonry wall. The experimental results are well in accordance with the simulation results. The front cross section dimension of crater is closely related to the radius of spherical explosive charge. A power function predictive model is developed to express the relationship between the radius of hole and the radius of explosive. Furthermore, with increasing the quantity of explosive charge, the number and ejection velocity of fragments are all increased. The relationship between maximum ejection velocity and the quantity of explosive also can be expressed as a power function model.

Study on Reduction Effect of Vibration Propagation due to Internal Explosion Using Composite Materials

With the increasing installation cases of underground explosive facilities (e.g., ammunition magazines, hydrogen tanks, etc.) in urban areas in recent years, the risk of internal explosions is also increasing. However, few studies on the measures for reducing damage by the ground vibration have been conducted except for maintaining safety distance. In this study, a method for attenuating the vibration propagated outward by installing a blast-proof panel was numerically and experimentally investigated. Two cubical reinforced concrete structures were manufactured according to the concrete strength and a blast-proof panel was installed on only one side of the structure. Then, acceleration sensors were installed on the external surface to evaluate the propagation of vibration outward depending on the installation of a blast-proof panel. Before a field experiment, a preliminary numerical simulation was performed. The results showed that the acceleration propagated outward could be effectively reduced by installing a blast-proof panel. Even though the performance of a blast-proof panel on vibration reduction was also investigated in the field experiment, significantly larger absolute accelerations were estimated due to the different experimental conditions. Finally, the vibration reduction effect of the blast-proof panel was numerically evaluated according to its thickness and the internal explosion load. A blast-proof panel more effectively reduced the acceleration propagated outward as its thickness increased and the explosion load decreased.