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2025,
45(4):
041101.
doi: 10.11883/bzycj-2024-0118
Abstract:
With the extensive application of new-type ammunitions and large-caliber heavy artillery, the non-contact killing mode caused by explosive shock is rapidly substituting the original direct-contact killing induced by bullets, fragments, etc. Characterized by high lethality and precision, it poses a greater threat to combatants and equipment. This study focuses on the technology of explosion shock wave detection and evaluation, especially in the field of personal protection. It reviews typical explosion shock wave test environments, such as real-explosion tests and shock-tube tests, and analyzes the pros and cons of electrical and non-electrical test measurement methods. The progress of piezoresistive, piezoelectric, and optical-fiber sensors is discussed. The trend of sensors towards miniaturization and intelligentization is emphasized, and the urgent need for new sensing technologies is proposed. This study also introduces the shock-wave signal processing and over-pressure field reconstruction technologies integrated with artificial intelligence, and investigates the application of new technologies like compressed sensing technology and deep neural network technology. In addition, the overall situation of typical foreign portable explosion shock wave sensing systems are summarized. To enhance the comprehensive protection and emergency treatment capabilities of combatants in extreme environments, the necessity of rapidly developing a portable explosion shock wave detection and evaluation system with independent intellectual property rights is discussed.
With the extensive application of new-type ammunitions and large-caliber heavy artillery, the non-contact killing mode caused by explosive shock is rapidly substituting the original direct-contact killing induced by bullets, fragments, etc. Characterized by high lethality and precision, it poses a greater threat to combatants and equipment. This study focuses on the technology of explosion shock wave detection and evaluation, especially in the field of personal protection. It reviews typical explosion shock wave test environments, such as real-explosion tests and shock-tube tests, and analyzes the pros and cons of electrical and non-electrical test measurement methods. The progress of piezoresistive, piezoelectric, and optical-fiber sensors is discussed. The trend of sensors towards miniaturization and intelligentization is emphasized, and the urgent need for new sensing technologies is proposed. This study also introduces the shock-wave signal processing and over-pressure field reconstruction technologies integrated with artificial intelligence, and investigates the application of new technologies like compressed sensing technology and deep neural network technology. In addition, the overall situation of typical foreign portable explosion shock wave sensing systems are summarized. To enhance the comprehensive protection and emergency treatment capabilities of combatants in extreme environments, the necessity of rapidly developing a portable explosion shock wave detection and evaluation system with independent intellectual property rights is discussed.
2025,
45(4):
041401.
doi: 10.11883/bzycj-2024-0165
Abstract:
To investigate the effect of the longitudinal air gap on the detonation performance of HMX-based explosive, direct observation of steel plate deformation and damage under forward and slipping detonation of HMX based explosive was conducted based on the laser illumination combined with the ultra-high speed framing imaging technology. The multi-position optical speed measurement technology was also introduced to continuously measure the speed of steel plate, which enables a multidimensional characterization and quantitative research on steel plate damage under the influence of air gaps. It is found that when the air gap width is 0.05, 0.10 and 0.20 mm, the motion mode of the steel plate changes obviously under the forward detonation. The trend of the center point movement changes from step rising to oblique wave rising, indicating a notable elongation of the lead time of detonation wave. And the steel plate also has an obvious deformation and breakdown. Driven by slipping detonation, the motion patterns across various points of the steel plate are largely uniform, with only marginal variations in the lead time of detonation wave. No significant deformation or rupture of the steel plate is observed. It is considered that the wedge-shaped wave formed by the precursor shock wave and detonation waves is the key to the breakdown of the bottom of steel plate in the case of forward detonation. However, the momentum component of the precursor shock wave and detonation wave acting on the side of steel plate in the case of slipping detonation is small, so that no obvious damage occurs. This article also provides a lot of quantitative data on the deformation of steel plates subjected to longitudinal air gaps, which can provide high-precision experimental data for the related numerical simulations and theoretical analysis work.
To investigate the effect of the longitudinal air gap on the detonation performance of HMX-based explosive, direct observation of steel plate deformation and damage under forward and slipping detonation of HMX based explosive was conducted based on the laser illumination combined with the ultra-high speed framing imaging technology. The multi-position optical speed measurement technology was also introduced to continuously measure the speed of steel plate, which enables a multidimensional characterization and quantitative research on steel plate damage under the influence of air gaps. It is found that when the air gap width is 0.05, 0.10 and 0.20 mm, the motion mode of the steel plate changes obviously under the forward detonation. The trend of the center point movement changes from step rising to oblique wave rising, indicating a notable elongation of the lead time of detonation wave. And the steel plate also has an obvious deformation and breakdown. Driven by slipping detonation, the motion patterns across various points of the steel plate are largely uniform, with only marginal variations in the lead time of detonation wave. No significant deformation or rupture of the steel plate is observed. It is considered that the wedge-shaped wave formed by the precursor shock wave and detonation waves is the key to the breakdown of the bottom of steel plate in the case of forward detonation. However, the momentum component of the precursor shock wave and detonation wave acting on the side of steel plate in the case of slipping detonation is small, so that no obvious damage occurs. This article also provides a lot of quantitative data on the deformation of steel plates subjected to longitudinal air gaps, which can provide high-precision experimental data for the related numerical simulations and theoretical analysis work.
2025,
45(4):
041402.
doi: 10.11883/bzycj-2024-0163
Abstract:
To discuss the flying gap effect of the metal flyer on the initiating behavior for TATB-based explosives, initiation experiments for PBX-6 and PBXL-7 were performed. The target velocity and shape of the flyer to explosives were obtained using a 1 550 nm photon Doppler velocimetry. The running distance to detonation (RDTD) of explosive samples was gained by a Terahertz-wave Doppler interferometric velocimetry at the center point. The relationship between the experiment data captured above was analyzed. It reveals that the running distance to detonation of the TATB-based explosive changes non-monotonously with the increase of gap. With the gap increasing from zero to 20 mm, there are five stages. The initial stage is named S0, the flyer velocity declining stage is named S1, the free running stage of spallation is named S2, the remerging stage when the main flyer catches up and remerging with its spallation layer is named S3, and the stage when the main flyer and spallation are united as one is named S4. The RDTD for the TATB-based explosive is the smallest when the flyer velocity comes to stage S4, the RDTD at stage S0 is the next, and the RDTD at the velocity declining stage S1 and remerging stage S3 are the worst together. These experiment results suggest that the initiating performance of TATB-based explosives impacted by the flyer is not always better than the gap layer results. The initiation mechanism of explosives by flyer under different gaps is probably related to the target velocity together with the structure of the flyer. The simplex target velocity rising of flyer can’t always make the running distance to detonation of TATB-based explosives shorter. The initiation mechanism of TATB-based explosives impacted by flyer is more complex than the gap layer, requiring much experiment data and numerical simulation for further discussion.
To discuss the flying gap effect of the metal flyer on the initiating behavior for TATB-based explosives, initiation experiments for PBX-6 and PBXL-7 were performed. The target velocity and shape of the flyer to explosives were obtained using a 1 550 nm photon Doppler velocimetry. The running distance to detonation (RDTD) of explosive samples was gained by a Terahertz-wave Doppler interferometric velocimetry at the center point. The relationship between the experiment data captured above was analyzed. It reveals that the running distance to detonation of the TATB-based explosive changes non-monotonously with the increase of gap. With the gap increasing from zero to 20 mm, there are five stages. The initial stage is named S0, the flyer velocity declining stage is named S1, the free running stage of spallation is named S2, the remerging stage when the main flyer catches up and remerging with its spallation layer is named S3, and the stage when the main flyer and spallation are united as one is named S4. The RDTD for the TATB-based explosive is the smallest when the flyer velocity comes to stage S4, the RDTD at stage S0 is the next, and the RDTD at the velocity declining stage S1 and remerging stage S3 are the worst together. These experiment results suggest that the initiating performance of TATB-based explosives impacted by the flyer is not always better than the gap layer results. The initiation mechanism of explosives by flyer under different gaps is probably related to the target velocity together with the structure of the flyer. The simplex target velocity rising of flyer can’t always make the running distance to detonation of TATB-based explosives shorter. The initiation mechanism of TATB-based explosives impacted by flyer is more complex than the gap layer, requiring much experiment data and numerical simulation for further discussion.
2025,
45(4):
041403.
doi: 10.11883/bzycj-2024-0132
Abstract:
The sheet explosive loading technology is a crucial method for evaluating the dynamic response of the space structure under the X-ray radiation in laboratory. To achieve the ultra-low specific impulse explosive loading required for the structural assessment of new space vehicles, a sheet explosive has been developed, primarily composed of PETN as the main explosive and polymer rubber as the binder. The mass fraction of PETN is 90%–92%, the thickness range is 0.15–0.20 mm, the density range is 1.63–1.68 g/cm3, and the explosive velocity range is 7.44–7.71 km/s. To verify the high-impact initiation sensitivity of the sheet explosive, three rounds of verification experiments were designed based on the blast marketing method. In the experiment, the sheet explosive was directly applied to the effect plate or a certain air gap reserved between the sheet explosive and the effect plate. The detonation of the explosive was confirmed by examining the explosive marks left on the effect plate post-explosion. The experimental results show that the sheet explosive with a thickness of 0.15–0.50 mm can be reliably detonated by a mild detonating fuse with a charge line density of 0.2 g/m, and the explosive strips with a thickness of 0.20–0.50 mm can reliably transmit detonation. The specific impulse characteristics of the sheet explosives with different diameters and thicknesses were measured and studied by the impact pendulum measurement device. Combined with theoretical analysis, the specific impulse calculation model of the sheet explosive was used to perform polynomial fitting on the specific impulse direct measurement data of the sheet explosives with the thicknesses of 0.20, 0.30, 0.40 and 0.50 mm, respectively. The specific impulse values of sheet explosives with four thicknesses were linearly fitted. The results show that the specific impulse of the sheet explosive is proportional to the thickness and the ratio coefficient is 3 418.56 Pa·s/mm. The development of ultra-thin sheet explosive with a thickness of 0.2 mm and a specific impulse of about 680 Pa·s was successfully realized.
The sheet explosive loading technology is a crucial method for evaluating the dynamic response of the space structure under the X-ray radiation in laboratory. To achieve the ultra-low specific impulse explosive loading required for the structural assessment of new space vehicles, a sheet explosive has been developed, primarily composed of PETN as the main explosive and polymer rubber as the binder. The mass fraction of PETN is 90%–92%, the thickness range is 0.15–0.20 mm, the density range is 1.63–1.68 g/cm3, and the explosive velocity range is 7.44–7.71 km/s. To verify the high-impact initiation sensitivity of the sheet explosive, three rounds of verification experiments were designed based on the blast marketing method. In the experiment, the sheet explosive was directly applied to the effect plate or a certain air gap reserved between the sheet explosive and the effect plate. The detonation of the explosive was confirmed by examining the explosive marks left on the effect plate post-explosion. The experimental results show that the sheet explosive with a thickness of 0.15–0.50 mm can be reliably detonated by a mild detonating fuse with a charge line density of 0.2 g/m, and the explosive strips with a thickness of 0.20–0.50 mm can reliably transmit detonation. The specific impulse characteristics of the sheet explosives with different diameters and thicknesses were measured and studied by the impact pendulum measurement device. Combined with theoretical analysis, the specific impulse calculation model of the sheet explosive was used to perform polynomial fitting on the specific impulse direct measurement data of the sheet explosives with the thicknesses of 0.20, 0.30, 0.40 and 0.50 mm, respectively. The specific impulse values of sheet explosives with four thicknesses were linearly fitted. The results show that the specific impulse of the sheet explosive is proportional to the thickness and the ratio coefficient is 3 418.56 Pa·s/mm. The development of ultra-thin sheet explosive with a thickness of 0.2 mm and a specific impulse of about 680 Pa·s was successfully realized.
2025,
45(4):
041404.
doi: 10.11883/bzycj-2024-0218
Abstract:
In order to predict the quasi-static pressure of internal explosion in a closed environment composed of aluminum containing active materials and explosive rings, this paper summarizes the existing quasi-static pressure calculation models for hydrogen, oxygen, and nitrogen explosives considering post ignition effects, and proposes an optimization method for the quasi-static pressure calculation mode applicable to internal explosion of aluminum containing composite charges. After obtaining the ideal maximum reaction heat using the Geiss theorem, this method uses a parameter correction related to the aluminum containing composite explosive itself. Taking Herzog as an example, a specific prediction formula is provided. Then, composite charges of active materials and explosives, as well as aluminum containing explosives, were tested for implosion. Typical overpressure curves were provided, and the method for obtaining quasi-static pressure in the tests and related sources were explained. The experimental data was compared and analyzed with the quasi-static pressure results calculated by the established optimization model, demonstrating the reliability of the modified model. At the same time, the internal explosion results of two types of explosives were compared, and the calculation model was extended to general aluminum containing explosives. The accuracy of the model was verified using quasi-static pressure data from relevant literature, and the reasons for errors and possible improvement methods were analyzed. The research results show that the established quasi-static pressure correction model for post combustion of composite explosives is in good agreement with experimental and literature data, with an average error of 9.1% and a maximum error of 15.8%; The average error of the calculation results for aluminum containing explosives is 12.1%, with a maximum error of 20.6%.
In order to predict the quasi-static pressure of internal explosion in a closed environment composed of aluminum containing active materials and explosive rings, this paper summarizes the existing quasi-static pressure calculation models for hydrogen, oxygen, and nitrogen explosives considering post ignition effects, and proposes an optimization method for the quasi-static pressure calculation mode applicable to internal explosion of aluminum containing composite charges. After obtaining the ideal maximum reaction heat using the Geiss theorem, this method uses a parameter correction related to the aluminum containing composite explosive itself. Taking Herzog as an example, a specific prediction formula is provided. Then, composite charges of active materials and explosives, as well as aluminum containing explosives, were tested for implosion. Typical overpressure curves were provided, and the method for obtaining quasi-static pressure in the tests and related sources were explained. The experimental data was compared and analyzed with the quasi-static pressure results calculated by the established optimization model, demonstrating the reliability of the modified model. At the same time, the internal explosion results of two types of explosives were compared, and the calculation model was extended to general aluminum containing explosives. The accuracy of the model was verified using quasi-static pressure data from relevant literature, and the reasons for errors and possible improvement methods were analyzed. The research results show that the established quasi-static pressure correction model for post combustion of composite explosives is in good agreement with experimental and literature data, with an average error of 9.1% and a maximum error of 15.8%; The average error of the calculation results for aluminum containing explosives is 12.1%, with a maximum error of 20.6%.
2025,
45(4):
041405.
doi: 10.11883/bzycj-2024-0117
Abstract:
In this paper, the microspheres in flying-ash are used as sensitizer and inert additive to prepare the low detonation velocity emulsion explosives. The detonation velocity and the parameters of explosive shock wave in the air of emulsion explosives were measured by the probe method, the lead column compression method and the air explosion method, respectively. The safety of emulsion explosives was tested by the storage life experiment and thermal analysis experiment. The experimental results show that the detonation velocity, the brisance, the peak pressure, the positive impulse and the positive pressure action time of shock wave of emulsion explosives increased first and then decreased with the increase of the content of flying-ash microspheres. When the content of flying-ash microspheres was 15%, the detonation performance of emulsion explosive was the best, and when the content of flying-ash microspheres was 45% , the detonation velocity of the explosive decreased obviously. Meanwhile, the detonation velocity ranged from 2191 to 2312 m/s, which can satisfy the condition of using explosive for explosive welding. In addition, it is found that the detonation performance of emulsion explosives with D50=79 μm flying-ash microspheres was higher than those of flying-ash microspheres with D50=116 and 47 μm. The storage life and thermal analysis results indicate that the storage life of low detonation velocity emulsion explosives with flying-ash microspheres is significantly better than that of traditional low detonation velocity emulsion explosive with clay particles, the activation energy of thermal decomposition of the emulsion explosive with 15% flying-ash microspheres was only 0.3% higher than that of emulsion matrix. The results also show that the addition of flying-ash microspheres has no obvious effect on the thermal stability of the emulsion matrix. The research results have important reference value for green resource disposal of coal-based solid waste and formulation design of the low detonation velocity emulsion explosive.
In this paper, the microspheres in flying-ash are used as sensitizer and inert additive to prepare the low detonation velocity emulsion explosives. The detonation velocity and the parameters of explosive shock wave in the air of emulsion explosives were measured by the probe method, the lead column compression method and the air explosion method, respectively. The safety of emulsion explosives was tested by the storage life experiment and thermal analysis experiment. The experimental results show that the detonation velocity, the brisance, the peak pressure, the positive impulse and the positive pressure action time of shock wave of emulsion explosives increased first and then decreased with the increase of the content of flying-ash microspheres. When the content of flying-ash microspheres was 15%, the detonation performance of emulsion explosive was the best, and when the content of flying-ash microspheres was 45% , the detonation velocity of the explosive decreased obviously. Meanwhile, the detonation velocity ranged from 2191 to 2312 m/s, which can satisfy the condition of using explosive for explosive welding. In addition, it is found that the detonation performance of emulsion explosives with D50=79 μm flying-ash microspheres was higher than those of flying-ash microspheres with D50=116 and 47 μm. The storage life and thermal analysis results indicate that the storage life of low detonation velocity emulsion explosives with flying-ash microspheres is significantly better than that of traditional low detonation velocity emulsion explosive with clay particles, the activation energy of thermal decomposition of the emulsion explosive with 15% flying-ash microspheres was only 0.3% higher than that of emulsion matrix. The results also show that the addition of flying-ash microspheres has no obvious effect on the thermal stability of the emulsion matrix. The research results have important reference value for green resource disposal of coal-based solid waste and formulation design of the low detonation velocity emulsion explosive.
2025,
45(4):
041406.
doi: 10.11883/bzycj-2024-0109
Abstract:
For the launch safety problem of the typical CL-20-based high detonation velocity pressed explosive (C-1, 94.5% CL-20+5.5% additive), the impact response characteristics of the explosive were studied by a large-scale hammer test with 400 kg, which has an impact loading curve similar to the loading characteristics of artillery chamber pressure. Meanwhile, the improved stress rate characterization method, the lower limit method, and the drop height method were used to characterize the drop hammer impact response characteristics of the explosive, and compared with the same kind of pressed explosives JO-8 and JH-2. The improved stress rate characterization method is obtained by improving the data processing process based on existing criteria and weakening the sensitivity of the original criterion formula to oscillatory waveforms. The measured stress curves and characterization parameters of the bottom of the three pressed explosives under different drop heights are obtained by tests, and the impact sensitivity differences of the explosives and influence factors of the impact sensitivity of C-1 are discussed. The results show that the improved stress rate characterization method has certain effectiveness and universality for characterizing the impact sensitivity of explosives. Meanwhile, the improved stress rate characterization method is consistent with other methods in reflecting the law. The drop height of C-1 (H50) is 1.0 m, which is 62.50% and 50.00% of JO-8 and JH-2, respectively; the peak stress of the backseat corresponding to non-detonation (σ0) is 748.90 MPa, which is 85.42% and 64.33% of JO-8 and JH-2, respectively; the safety stress rate parameter (C0) is 344 GPa2/s, which is 45.87% and 39.14% of JO-8 and JH-2, respectively. The molecular structure of CL-20, the mechanical properties, and the thermal-chemical characteristics of the C-1 explosive cylinder are the main factors that make its impact sensitivity higher than JO-8 and JH-2. The research results can provide a reference for the application and design calculation of CL-20-based high detonation velocity pressed explosives in a high overload environment.
For the launch safety problem of the typical CL-20-based high detonation velocity pressed explosive (C-1, 94.5% CL-20+5.5% additive), the impact response characteristics of the explosive were studied by a large-scale hammer test with 400 kg, which has an impact loading curve similar to the loading characteristics of artillery chamber pressure. Meanwhile, the improved stress rate characterization method, the lower limit method, and the drop height method were used to characterize the drop hammer impact response characteristics of the explosive, and compared with the same kind of pressed explosives JO-8 and JH-2. The improved stress rate characterization method is obtained by improving the data processing process based on existing criteria and weakening the sensitivity of the original criterion formula to oscillatory waveforms. The measured stress curves and characterization parameters of the bottom of the three pressed explosives under different drop heights are obtained by tests, and the impact sensitivity differences of the explosives and influence factors of the impact sensitivity of C-1 are discussed. The results show that the improved stress rate characterization method has certain effectiveness and universality for characterizing the impact sensitivity of explosives. Meanwhile, the improved stress rate characterization method is consistent with other methods in reflecting the law. The drop height of C-1 (H50) is 1.0 m, which is 62.50% and 50.00% of JO-8 and JH-2, respectively; the peak stress of the backseat corresponding to non-detonation (σ0) is 748.90 MPa, which is 85.42% and 64.33% of JO-8 and JH-2, respectively; the safety stress rate parameter (C0) is 344 GPa2/s, which is 45.87% and 39.14% of JO-8 and JH-2, respectively. The molecular structure of CL-20, the mechanical properties, and the thermal-chemical characteristics of the C-1 explosive cylinder are the main factors that make its impact sensitivity higher than JO-8 and JH-2. The research results can provide a reference for the application and design calculation of CL-20-based high detonation velocity pressed explosives in a high overload environment.
2025,
45(4):
043301.
doi: 10.11883/bzycj-2024-0248
Abstract:
The penetration depth of the earth-penetrating projectile is a basic problem in the design of protection engineering. Scaled testing is an important method to study the penetration law. The size effect between the model test results and the prototype is a problem that must be solved to establish the calculation method of penetration using scaled tests. In this study, the stress and strain state evolution of the rock-like target medium subjected to the penetration of earth-penetrating projectiles and the penetration resistance function of the projectiles were derived using cavity expansion theory. The formula for the caliber coefficient characterizing the size effect was obtained, and a simplified analysis of the nose shape coefficient and caliber coefficient was conducted using curve fitting and Taylor expansion within the penetration velocity range of the conventional earth-penetrating weapons. A practical calculation formula for the penetration depth of conventional earth-penetrating weapons into rock-like media was proposed, whose coefficients can be directly determined by parameters of target and projectiles. The results show that the main influencing factor of the projectile’s penetration resistance is the impedance of the target. The source of the size effect is originated from the fact that the ranges of the target damage zones do not satisfy the geometric similarity law. The nose shape coefficient can be simplified into a linear function of the projectile’s aspect ratio, and the nose shape coefficient of a flat-nosed projectile is 0.57. The caliber coefficient of the projectile is determined by the ratio of the cavity radius of the penetration to the radius of the fracture zone and can be taken as 1.2−1.4 for conventional earth-penetrating weapons. The theoretical calculation formula of penetration depth is in good agreement with experimental results, and thus, has high reliability.
The penetration depth of the earth-penetrating projectile is a basic problem in the design of protection engineering. Scaled testing is an important method to study the penetration law. The size effect between the model test results and the prototype is a problem that must be solved to establish the calculation method of penetration using scaled tests. In this study, the stress and strain state evolution of the rock-like target medium subjected to the penetration of earth-penetrating projectiles and the penetration resistance function of the projectiles were derived using cavity expansion theory. The formula for the caliber coefficient characterizing the size effect was obtained, and a simplified analysis of the nose shape coefficient and caliber coefficient was conducted using curve fitting and Taylor expansion within the penetration velocity range of the conventional earth-penetrating weapons. A practical calculation formula for the penetration depth of conventional earth-penetrating weapons into rock-like media was proposed, whose coefficients can be directly determined by parameters of target and projectiles. The results show that the main influencing factor of the projectile’s penetration resistance is the impedance of the target. The source of the size effect is originated from the fact that the ranges of the target damage zones do not satisfy the geometric similarity law. The nose shape coefficient can be simplified into a linear function of the projectile’s aspect ratio, and the nose shape coefficient of a flat-nosed projectile is 0.57. The caliber coefficient of the projectile is determined by the ratio of the cavity radius of the penetration to the radius of the fracture zone and can be taken as 1.2−1.4 for conventional earth-penetrating weapons. The theoretical calculation formula of penetration depth is in good agreement with experimental results, and thus, has high reliability.
2025,
45(4):
043302.
doi: 10.11883/bzycj-2024-0136
Abstract:
Aiming at the resistance evaluation and engineering design of the rock-rubble concrete shield under the combination of penetration and explosion of Earth Penetrating Weapons, firstly, a finite element modeling method for rock-rubble concrete shields was proposed. By conducting numerical simulations of quasi-static and penetration tests on ultra-high performance concrete (UHPC) targets containing different coarse aggregate types (corundum and basalt), particle sizes (5–15, 5–20, 35–45, and 65–75 mm), and volume fractions (15% and 30%), the reliability of the finite element analysis approach was thoroughly verified. Then, using the semi-infinite rock-rubble concrete shield penetrated by the small-diameter bomb (SDB) as a case study, the quantitative influence of type (corundum, basalt, and granite) and dimensionless particle size of rock-rubble (ranging from 0.3 to 2.2 times the projectile diameter) on the penetration depth was analyzed, and optimal design recommendations were determined. Furthermore, the penetration analyses of three typical prototype warheads, i.e., SDB, WDU-43/B, and BLU-109/B, were carried out, and the corresponding penetration resistances of normal strength concrete (NSC), ultra-high performance concrete, and corundum rubble concrete (CRC) shields against the above three warheads were quantitatively compared. Finally, the engineering design method for the CRC shield under the combined effects of penetration and explosion of prototype warheads was proposed. The results indicate that the CRC shield containing the particle size of 1.3 to 1.7 times the projectile diameter exhibits the most excellent penetration resistance. Under the penetration of three types of warheads, the penetration depths in CRC shield were 0.29, 0.78, and 0.68 m, respectively, which are reduced by 61.8%–69.1% and 43.3%–58.0% compared to those in NSC and UHPC shields. Under the combined effects of penetration and explosion, the perforation limits of the CRC shield are 0.55, 1.41, and 1.48 m, while the scabbing limits are 1.11, 2.26, and 3.17 m. Compared with NSC and UHPC shields, the perforation limits are reduced by 58.5%–61.2% and 43.2%–58.1%, respectively, and the scabbing limits are reduced by 61.8%–69.2% and 34.7%–40.5%, respectively.
Aiming at the resistance evaluation and engineering design of the rock-rubble concrete shield under the combination of penetration and explosion of Earth Penetrating Weapons, firstly, a finite element modeling method for rock-rubble concrete shields was proposed. By conducting numerical simulations of quasi-static and penetration tests on ultra-high performance concrete (UHPC) targets containing different coarse aggregate types (corundum and basalt), particle sizes (5–15, 5–20, 35–45, and 65–75 mm), and volume fractions (15% and 30%), the reliability of the finite element analysis approach was thoroughly verified. Then, using the semi-infinite rock-rubble concrete shield penetrated by the small-diameter bomb (SDB) as a case study, the quantitative influence of type (corundum, basalt, and granite) and dimensionless particle size of rock-rubble (ranging from 0.3 to 2.2 times the projectile diameter) on the penetration depth was analyzed, and optimal design recommendations were determined. Furthermore, the penetration analyses of three typical prototype warheads, i.e., SDB, WDU-43/B, and BLU-109/B, were carried out, and the corresponding penetration resistances of normal strength concrete (NSC), ultra-high performance concrete, and corundum rubble concrete (CRC) shields against the above three warheads were quantitatively compared. Finally, the engineering design method for the CRC shield under the combined effects of penetration and explosion of prototype warheads was proposed. The results indicate that the CRC shield containing the particle size of 1.3 to 1.7 times the projectile diameter exhibits the most excellent penetration resistance. Under the penetration of three types of warheads, the penetration depths in CRC shield were 0.29, 0.78, and 0.68 m, respectively, which are reduced by 61.8%–69.1% and 43.3%–58.0% compared to those in NSC and UHPC shields. Under the combined effects of penetration and explosion, the perforation limits of the CRC shield are 0.55, 1.41, and 1.48 m, while the scabbing limits are 1.11, 2.26, and 3.17 m. Compared with NSC and UHPC shields, the perforation limits are reduced by 58.5%–61.2% and 43.2%–58.1%, respectively, and the scabbing limits are reduced by 61.8%–69.2% and 34.7%–40.5%, respectively.
2025,
45(4):
045101.
doi: 10.11883/bzycj-2024-0192
Abstract:
The evaluation of protective performance and optimization of the design of building structures under impact loading is a key issue of concern in the fields of national defense, civil engineering, and other military and civilian use. Lattice columns are often used as the main load-bearing components in engineering structures and are inevitably impacted by other unintentional loads under engineering service environments. In this paper, 1∶2 scaled-down secondary impact tests were carried out on lattice columns along different impact directions with the same impact energy each time and compared with single-impact lattice columns under the same total energy to analyze the force and deformation characteristics of the lattice columns under the impact loads. Then, based on the experimentally verified finite element model, a continuous secondary impact simulation was carried out on the foot-foot lattice column. The dynamic response of the lattice column subjected to two consecutive impacts with the same total energy was obtained, and the effects of different energy distributions on the impact force, residual displacement, and residual kinetic energy were analyzed. The results show that under the same total energy, the displacement of lattice columns under a single impact is greater than that of a secondary impact. The optimal energy distribution obtained by numerical simulation can reduce the residual displacement of members impacted along different directions by about 12%. When the lattice column is subjected to a larger proportion of energy for the first time or a smaller proportion of impact energy for the second time, the total energy absorbed by the column is smaller. Finally, based on the results of tests and numerical simulations, the maximum impact velocity at which the damaged column can withstand a second impact is proposed. The results of the study can provide a reference for the design method of lattice steel columns under such loading conditions.
The evaluation of protective performance and optimization of the design of building structures under impact loading is a key issue of concern in the fields of national defense, civil engineering, and other military and civilian use. Lattice columns are often used as the main load-bearing components in engineering structures and are inevitably impacted by other unintentional loads under engineering service environments. In this paper, 1∶2 scaled-down secondary impact tests were carried out on lattice columns along different impact directions with the same impact energy each time and compared with single-impact lattice columns under the same total energy to analyze the force and deformation characteristics of the lattice columns under the impact loads. Then, based on the experimentally verified finite element model, a continuous secondary impact simulation was carried out on the foot-foot lattice column. The dynamic response of the lattice column subjected to two consecutive impacts with the same total energy was obtained, and the effects of different energy distributions on the impact force, residual displacement, and residual kinetic energy were analyzed. The results show that under the same total energy, the displacement of lattice columns under a single impact is greater than that of a secondary impact. The optimal energy distribution obtained by numerical simulation can reduce the residual displacement of members impacted along different directions by about 12%. When the lattice column is subjected to a larger proportion of energy for the first time or a smaller proportion of impact energy for the second time, the total energy absorbed by the column is smaller. Finally, based on the results of tests and numerical simulations, the maximum impact velocity at which the damaged column can withstand a second impact is proposed. The results of the study can provide a reference for the design method of lattice steel columns under such loading conditions.
2025,
45(4):
045201.
doi: 10.11883/bzycj-2024-0089
Abstract:
Plasma blasting rock breaking technology is characterized by green, high efficiency, controllability, and has a good application prospect in deep rock breaking. In order to provide a new rock-breaking method for the rock-breaking engineering under deep stress, four groups of plasma sandstone blasting tests under different peripheral pressures were carried out. The morphology, structure and distribution of three-dimensional cracks inside the rock were comparatively analyzed by CT scanning and three-dimensional reconstruction, so as to study the effectiveness of the plasma blasting technology in rock breaking under different peripheral pressures. Meanwhile numerical simulation was conducted by using LS-DYNA to establish the plasma equivalent explosive model, supplementing the verification of the role of plasma blasting in the coupled stress field, and investigating the mechanism of plasma blasting under different pressures, as well as the internal crack expansion, distribution and damage evolution laws in the rock body in the blasting process. The results show that under the same voltage, with the increase of the 3D peripheral pressure, the number and distribution range of cracks on the surface of the rock exhibit a trend of gradual reduction, while the complexity of the cracks within the sandstone and the depth of penetration are significantly reduced. Due to the dynamic stress field generated by plasma blasting and the static stress coupling field generated by the surrounding pressure, the shock wave generated by the plasma blasting in the initial stage of the explosion plays a major role for the effect of different pressures under the action of the rock crack morphology and the center of the expansion of the region does not show obvious differences. With the attenuation of the shock wave, the 3D surrounding pressure in the middle and late stages of the plasma blasting process plays a decisive role in inhibiting the cracks of the rock mass expansion and damage evolution. At the same time, with the increase of the surrounding pressure, the more significant inhibition effect on the expansion of cracks in the rock body, resulting in the body fractal dimension and damage degree of 3D cracks in the rock body, while the role of the surrounding pressure approximately follows a linearly decreasing relationship.
Plasma blasting rock breaking technology is characterized by green, high efficiency, controllability, and has a good application prospect in deep rock breaking. In order to provide a new rock-breaking method for the rock-breaking engineering under deep stress, four groups of plasma sandstone blasting tests under different peripheral pressures were carried out. The morphology, structure and distribution of three-dimensional cracks inside the rock were comparatively analyzed by CT scanning and three-dimensional reconstruction, so as to study the effectiveness of the plasma blasting technology in rock breaking under different peripheral pressures. Meanwhile numerical simulation was conducted by using LS-DYNA to establish the plasma equivalent explosive model, supplementing the verification of the role of plasma blasting in the coupled stress field, and investigating the mechanism of plasma blasting under different pressures, as well as the internal crack expansion, distribution and damage evolution laws in the rock body in the blasting process. The results show that under the same voltage, with the increase of the 3D peripheral pressure, the number and distribution range of cracks on the surface of the rock exhibit a trend of gradual reduction, while the complexity of the cracks within the sandstone and the depth of penetration are significantly reduced. Due to the dynamic stress field generated by plasma blasting and the static stress coupling field generated by the surrounding pressure, the shock wave generated by the plasma blasting in the initial stage of the explosion plays a major role for the effect of different pressures under the action of the rock crack morphology and the center of the expansion of the region does not show obvious differences. With the attenuation of the shock wave, the 3D surrounding pressure in the middle and late stages of the plasma blasting process plays a decisive role in inhibiting the cracks of the rock mass expansion and damage evolution. At the same time, with the increase of the surrounding pressure, the more significant inhibition effect on the expansion of cracks in the rock body, resulting in the body fractal dimension and damage degree of 3D cracks in the rock body, while the role of the surrounding pressure approximately follows a linearly decreasing relationship.
2025,
45(4):
045202.
doi: 10.11883/bzycj-2024-0071
Abstract:
There are many microcracks and micropores in the rock, which will initiate, propagate, and coalescence under dynamic loading, leading to rock instability and failure. When blasting excavation is carried out, the retained rock mass will be subjected to the dynamic loading generated by cyclic blasting, resulting in cumulative damage, which will lead to the reduction of the rock mass strength, and even failure. In order to simulate this physical process, the existing rock dynamic damage constitutive model, which could perfectly describe the rock dynamic damage induced by blasting, was embedded into FLAC through secondary development to analyze the cumulative damage of rock mass under cyclic blasting. And then it was adopted to simulate the damage effect and stability of the rock slope with the locked segment under cyclic blasting. The stability of the slope under cyclic blasting was determined by the displacement criterion method, and the safety factor of the slope after each blasting was obtained by the strength reduction method. Finally, the relationship between the failure mode and stability of the slope and the location of the locked segment was discussed by analyzing the damage, displacement field, and safety factor of the numerical models for different locations of the locked segment in the soft interlayer. The results show that the slope stability gradually decreases with increasing the number of cyclic blasting after considering the cumulative damage effect of the rock slope. For the rock slope with the locked segment, the damage of the locked segment firstly occurs at both ends, and then propagates to the middle, in which the rock mass shows a progressive failure mode. Because the cumulative damage of the rock slope is considered, the safety factor of the slope will decrease after each blasting. When the cumulative damage is not considered, the safety factor of the slope is basically unchanged. The failure mode of the rock slope with a locked segment under cyclic blasting is the combination of dynamic tensile failure and shear failure caused by rock mass slip. The location of the locked segment in the weak interlayer affects the failure mode and stability of the slope. Therefore, when carrying out similar engineering activities, the cumulative damage effect of rock mass should be considered to avoid engineering accidents.
There are many microcracks and micropores in the rock, which will initiate, propagate, and coalescence under dynamic loading, leading to rock instability and failure. When blasting excavation is carried out, the retained rock mass will be subjected to the dynamic loading generated by cyclic blasting, resulting in cumulative damage, which will lead to the reduction of the rock mass strength, and even failure. In order to simulate this physical process, the existing rock dynamic damage constitutive model, which could perfectly describe the rock dynamic damage induced by blasting, was embedded into FLAC through secondary development to analyze the cumulative damage of rock mass under cyclic blasting. And then it was adopted to simulate the damage effect and stability of the rock slope with the locked segment under cyclic blasting. The stability of the slope under cyclic blasting was determined by the displacement criterion method, and the safety factor of the slope after each blasting was obtained by the strength reduction method. Finally, the relationship between the failure mode and stability of the slope and the location of the locked segment was discussed by analyzing the damage, displacement field, and safety factor of the numerical models for different locations of the locked segment in the soft interlayer. The results show that the slope stability gradually decreases with increasing the number of cyclic blasting after considering the cumulative damage effect of the rock slope. For the rock slope with the locked segment, the damage of the locked segment firstly occurs at both ends, and then propagates to the middle, in which the rock mass shows a progressive failure mode. Because the cumulative damage of the rock slope is considered, the safety factor of the slope will decrease after each blasting. When the cumulative damage is not considered, the safety factor of the slope is basically unchanged. The failure mode of the rock slope with a locked segment under cyclic blasting is the combination of dynamic tensile failure and shear failure caused by rock mass slip. The location of the locked segment in the weak interlayer affects the failure mode and stability of the slope. Therefore, when carrying out similar engineering activities, the cumulative damage effect of rock mass should be considered to avoid engineering accidents.
2025,
45(4):
045401.
doi: 10.11883/bzycj-2024-0142
Abstract:
Numerical simulation was carried out by using the Fluent simulation software and combining it with the situation of the working face 3906 in a mine to investigate the propagation law of gas explosion in a U-shaped ventilation coal mining face and to explore the sensitivities of the overpressure attenuation of a gas explosion to different influencing factors. The relative errors between the numerically-simulated results and experimental ones are less than 15%, which verifies the reliability of the mathematical model developed in this paper. Then, the key parameters, namely, grid size, iteration time step, and ignition temperature are optimized to 0.2 m, 0.05 ms, and1900 K, respectively. Numerical simulation indicates that the relationship between the peak of the explosion overpressure and the distance away from the explosion center of the coal face meets an exponential function relationship. The relationship between the arrival time of the peak explosion overpressure and the distance away from the explosion center meets a linear function. By designing an orthogonal array, 16 sets of data were obtained through simulation, and the following analyses were conducted based on this data. The extreme difference values of the three main control factors were obtained by using extreme difference analysis. The extreme difference value of the temperature is the greatest, the one of the gas concentration take the second, and the one of the gas accumulation area pressure is the least. The most significant impact of the temperature on the explosion overpressure attenuation in the numerical simulation, in which the R-value reaches 5.928. ANOVA analysis was carried out to study the significances of the main control factors affecting the explosion overpressure attenuation rate. In the three main control factors, the significance of the temperature is the most, the one of the gas accumulation zone pressure comes second, and the one of the gas concentration is the weakest. And the temperature shows a significance level of 31.835, while the other two factors are not significant.
Numerical simulation was carried out by using the Fluent simulation software and combining it with the situation of the working face 3906 in a mine to investigate the propagation law of gas explosion in a U-shaped ventilation coal mining face and to explore the sensitivities of the overpressure attenuation of a gas explosion to different influencing factors. The relative errors between the numerically-simulated results and experimental ones are less than 15%, which verifies the reliability of the mathematical model developed in this paper. Then, the key parameters, namely, grid size, iteration time step, and ignition temperature are optimized to 0.2 m, 0.05 ms, and
