Liquefaction testing at a saturated loess site was performed under the simulated earthquake ground motion induced by artificial explosions with micro-time intervals.The time histories of ground acceleration,pore water...Liquefaction testing at a saturated loess site was performed under the simulated earthquake ground motion induced by artificial explosions with micro-time intervals.The time histories of ground acceleration,pore water pressure and the ultimate value of residual strain were recorded and measured.The modified FEQdrain computation software was used to analyze the liquefaction.Both the test and the analysis confirm the objective occurrence of loess liquefaction.Furthermore,the reliability of the method of the loess liquefaction analysis based on FEQdrain and the model of pore water pressure development of saturated loess are examined.展开更多
Several methods of mixed programming with LabVIEW and Matlab are introduced.Taking explosin test as application background,the design method and implementation process using MathScript node and COM technology are main...Several methods of mixed programming with LabVIEW and Matlab are introduced.Taking explosin test as application background,the design method and implementation process using MathScript node and COM technology are mainly discussed.Based on this,the advantages of LabVIEW＇s interface development and Matlab＇s rich data operation functions are combined to achieve the fitting of explosion pressure field and dynamic compensation of temperature measured.展开更多
The accelerated demand for engineering services has led to the extensive utilization of engineering blasting techniques.Blasting-induced changes in loess microstructure(e.g.particle breakage,pore structure change)dire...The accelerated demand for engineering services has led to the extensive utilization of engineering blasting techniques.Blasting-induced changes in loess microstructure(e.g.particle breakage,pore structure change)directly affect its macroscopic mechanical properties.However,there remains a notable lack of studies on the impact of explosions on loess microstructure and the quantificationof loess microstructure.This study employed micro-computed tomography(μ-CT)technology to examine loess samples extracted from the surrounding area of the explosion cavity,systematically investigating the volume,orientation,and morphological characteristics of particles and pores.The research findings indicated that the explosion caused a break for the particles with a diameter larger than 10μm,and the number of smaller particles increased.Blasting decreased the particle sphericity and orientation angle.The reduction in porosity was primarily attributed to a decrease in the volume of both macropores and mesopores,with a greater reduction in the volume of mesopores.Although the number of micropores increased,the volume change was insignificant.Furthermore,the explosion increased the pore fractal dimension and patch density,suggesting a more complex and fragmented pore structure.Moreover,the pore throat radius and channel length decreased with decreasing distance from the explosion cavity(D_(EC)),indicating that the pore's connectivity reduced.The radius of the blasting cavity was approximately 0.35 m.Additionally,the loess zone surrounding the blasting cavity was divided into failure,plastic,and elastic zones using the D_(EC)=0.2 m and 1.2 m as the boundaries.The impacts of the explosion on loess were mainly within the range of D_(EC)less than 1.20 m.The analysis of the traits,patterns,and mechanisms of explosions'impact on the loess's microstructure can provide microscopic insight into the macro-dynamic behavior,assess the impact of explosions on the surrounding loess,and identify the potential geological hazards triggered by blasting,which offers a theoretical foundation for the subsequent engineering design and security measures.展开更多
In this study,an explicit dynamic constitutive model was established for ultra high toughness cementitious composites(UHTCCs).The model,based on the Holmquist–Johnson–Cook(HJC)model,includes tensile and compressive ...In this study,an explicit dynamic constitutive model was established for ultra high toughness cementitious composites(UHTCCs).The model,based on the Holmquist–Johnson–Cook(HJC)model,includes tensile and compressive damage evolution,hydrostatic pressure,strain rate,and the Lode angle effect.The proposed model was embedded in LS-DYNA software and then comprehensive tests were carried on a hexahedral brick element formulation under uniaxial,biaxial,and triaxial stress states to verify its rationality through comparisons with results determined by the HJC and Karagozian&Case(K&C)models.Finally,the proposed model was used to simulate the damage caused to UHTCC targets subjected to blast by embedded explosive and projectile penetration,and predictions were compared with corresponding experimental results.The results of the numerical simulations showed that our proposed model was more accurate than the HJC model in predicting the size of the crater,penetration depth,and the distribution of cracks inside the target following the blast or high-speed impact loading.展开更多
The proposed prediction model for estimating the maximum rebound ratio was applied to a field explosion test, Mandai test in Singapore. The estimated possible maximum peak particle velocities(PPVs) were compared with ...The proposed prediction model for estimating the maximum rebound ratio was applied to a field explosion test, Mandai test in Singapore. The estimated possible maximum peak particle velocities(PPVs) were compared with the field records. Three of the four available field-recorded PPVs lie exactly below the estimated possible maximum values as expected, while the fourth available field-recorded PPV lies close to and a bit higher than the estimated maximum possible PPV. The comparison results show that the predicted PPVs from the proposed prediction model for the maximum rebound ratio match the field-recorded PPVs better than those from two empirical formulae. The very good agreement between the estimated and field-recorded values validates the proposed prediction model for estimating PPV in a rock mass with a set of joints due to application of a two dimensional compressional wave at the boundary of a tunnel or a borehole.展开更多
The transmission ratio along the radian direction normal to the joints was studied in the Universal Distinct Element Code （UDEC）. The variation of the transmission ratio with the ratio of joint spacing to wavelength...The transmission ratio along the radian direction normal to the joints was studied in the Universal Distinct Element Code （UDEC）. The variation of the transmission ratio with the ratio of joint spacing to wavelength was generalized into a general curve, which was determined by two critical points. The relationship between the two critical points and the affecting factors, quantity of joints and the normalized normal stiffness of joints, were obtained. A prediction model of the transmission ratio in the radian direction normal to the joints was proposed. The proposed model was applied to a field explosion test. The estimated values of the peak particle velocity from the prediction model were compared with the field records. The comparisons showed that the prediction model of the transmission ratio in the direction normal to the joints in the process of 2-D compressional wave propagation through multiple parallel joints is reliable.展开更多
This paper pays attention to the analysis of overall macroscopic process of wavemaking induced by explosion. Based on establishing the simplified model and MAC method, the numerical simulations for formulating crater ...This paper pays attention to the analysis of overall macroscopic process of wavemaking induced by explosion. Based on establishing the simplified model and MAC method, the numerical simulations for formulating crater induced by touching water surface explosion, the bubble jumping out of the water surface induced by underwater explosion as well as hollow column formation for large equivalent explosion etc were carried out. In order to predict the wave field, the scheme simulated by falling and evoluting of an ″equivalent cylinder″ were proposed. In addition to researching the wavemaking response in a harbour, two joining methods in time domain were presented. The results indicate that the model and numerical methods are feasible.展开更多
With the increasing demand for secure infrastructure such as hydrogen refueling stations,chemical plants,and energy storage systems,the need for protective structures capable of withstanding close-in detonations has b...With the increasing demand for secure infrastructure such as hydrogen refueling stations,chemical plants,and energy storage systems,the need for protective structures capable of withstanding close-in detonations has become more critical.Existing design guidelines for protective walls(e.g.,UFC 3-340-02)primarily address mid-and far-field explosions,providing limited insights into near-field effects.Considering the effect of slight slopes(<40°)on reducing maximum reflected overpressure is deemed negligible.This study investigated the effectiveness of a reinforced concrete(RC)modular protection system(MPS)incorpo rating a diagonally tapered wall in attenuating re flected overpressures from closein detonations.Full-scale field experiments using a 51.3 kg TNT charge,representing the explosion energy of a typical hydrogen vessel rupture,demonstrated that a wall with a 7°slope significantly outperformed a vertical wall of equivalent concrete volume in terms of blast resistance.Observed structural responses included cracking,horizontal shear failure,and overturning.Complementary simulations using a validated computational fluid dynamics(CFD)model showed that the tapered wall reduced peak overpressure by 30%-40%compared to an equivalent vertical wall.This result highlights the potential of minor geometric modifications to enhance blast resilience.The tapered design effectively redirects incident blast waves,reducing localized damage while also conserving material,thus preserving modular benefits such as ease of transport and reusability.These findings suggest that diagonally tapered RC-based MPSs can offer a practical and resilient solution for industrial and military applications subject to near-field or sequential blast threats.展开更多
基金China Ministry of Science and Technology (Granted No.2000-35)Registration No.for Publications of Lanzhou Institute of Seismology,CSB:LC2002-001.
文摘Liquefaction testing at a saturated loess site was performed under the simulated earthquake ground motion induced by artificial explosions with micro-time intervals.The time histories of ground acceleration,pore water pressure and the ultimate value of residual strain were recorded and measured.The modified FEQdrain computation software was used to analyze the liquefaction.Both the test and the analysis confirm the objective occurrence of loess liquefaction.Furthermore,the reliability of the method of the loess liquefaction analysis based on FEQdrain and the model of pore water pressure development of saturated loess are examined.
文摘Several methods of mixed programming with LabVIEW and Matlab are introduced.Taking explosin test as application background,the design method and implementation process using MathScript node and COM technology are mainly discussed.Based on this,the advantages of LabVIEW＇s interface development and Matlab＇s rich data operation functions are combined to achieve the fitting of explosion pressure field and dynamic compensation of temperature measured.
基金financiallysupported by the National Key&Program of China(Grant No.2022YFC3003403)the National Natural Science Foundation of China(Grant Nos.42472348 and 42220104005).
文摘The accelerated demand for engineering services has led to the extensive utilization of engineering blasting techniques.Blasting-induced changes in loess microstructure(e.g.particle breakage,pore structure change)directly affect its macroscopic mechanical properties.However,there remains a notable lack of studies on the impact of explosions on loess microstructure and the quantificationof loess microstructure.This study employed micro-computed tomography(μ-CT)technology to examine loess samples extracted from the surrounding area of the explosion cavity,systematically investigating the volume,orientation,and morphological characteristics of particles and pores.The research findings indicated that the explosion caused a break for the particles with a diameter larger than 10μm,and the number of smaller particles increased.Blasting decreased the particle sphericity and orientation angle.The reduction in porosity was primarily attributed to a decrease in the volume of both macropores and mesopores,with a greater reduction in the volume of mesopores.Although the number of micropores increased,the volume change was insignificant.Furthermore,the explosion increased the pore fractal dimension and patch density,suggesting a more complex and fragmented pore structure.Moreover,the pore throat radius and channel length decreased with decreasing distance from the explosion cavity(D_(EC)),indicating that the pore's connectivity reduced.The radius of the blasting cavity was approximately 0.35 m.Additionally,the loess zone surrounding the blasting cavity was divided into failure,plastic,and elastic zones using the D_(EC)=0.2 m and 1.2 m as the boundaries.The impacts of the explosion on loess were mainly within the range of D_(EC)less than 1.20 m.The analysis of the traits,patterns,and mechanisms of explosions'impact on the loess's microstructure can provide microscopic insight into the macro-dynamic behavior,assess the impact of explosions on the surrounding loess,and identify the potential geological hazards triggered by blasting,which offers a theoretical foundation for the subsequent engineering design and security measures.
基金Project supported by the National Natural Science Foundation of China(Nos.51678522 , 51878601)。
文摘In this study,an explicit dynamic constitutive model was established for ultra high toughness cementitious composites(UHTCCs).The model,based on the Holmquist–Johnson–Cook(HJC)model,includes tensile and compressive damage evolution,hydrostatic pressure,strain rate,and the Lode angle effect.The proposed model was embedded in LS-DYNA software and then comprehensive tests were carried on a hexahedral brick element formulation under uniaxial,biaxial,and triaxial stress states to verify its rationality through comparisons with results determined by the HJC and Karagozian&Case(K&C)models.Finally,the proposed model was used to simulate the damage caused to UHTCC targets subjected to blast by embedded explosive and projectile penetration,and predictions were compared with corresponding experimental results.The results of the numerical simulations showed that our proposed model was more accurate than the HJC model in predicting the size of the crater,penetration depth,and the distribution of cracks inside the target following the blast or high-speed impact loading.
基金Project(50278057) supported by the National Natural Science Foundation of Chinaproject(2002CB412703) supported by the Major State Basic Research Development Program of China
文摘The proposed prediction model for estimating the maximum rebound ratio was applied to a field explosion test, Mandai test in Singapore. The estimated possible maximum peak particle velocities(PPVs) were compared with the field records. Three of the four available field-recorded PPVs lie exactly below the estimated possible maximum values as expected, while the fourth available field-recorded PPV lies close to and a bit higher than the estimated maximum possible PPV. The comparison results show that the predicted PPVs from the proposed prediction model for the maximum rebound ratio match the field-recorded PPVs better than those from two empirical formulae. The very good agreement between the estimated and field-recorded values validates the proposed prediction model for estimating PPV in a rock mass with a set of joints due to application of a two dimensional compressional wave at the boundary of a tunnel or a borehole.
基金The work was partially supported by the Major State Basic Research Development Program of China (No. 2002CB412703).
文摘The transmission ratio along the radian direction normal to the joints was studied in the Universal Distinct Element Code （UDEC）. The variation of the transmission ratio with the ratio of joint spacing to wavelength was generalized into a general curve, which was determined by two critical points. The relationship between the two critical points and the affecting factors, quantity of joints and the normalized normal stiffness of joints, were obtained. A prediction model of the transmission ratio in the radian direction normal to the joints was proposed. The proposed model was applied to a field explosion test. The estimated values of the peak particle velocity from the prediction model were compared with the field records. The comparisons showed that the prediction model of the transmission ratio in the direction normal to the joints in the process of 2-D compressional wave propagation through multiple parallel joints is reliable.
文摘This paper pays attention to the analysis of overall macroscopic process of wavemaking induced by explosion. Based on establishing the simplified model and MAC method, the numerical simulations for formulating crater induced by touching water surface explosion, the bubble jumping out of the water surface induced by underwater explosion as well as hollow column formation for large equivalent explosion etc were carried out. In order to predict the wave field, the scheme simulated by falling and evoluting of an ″equivalent cylinder″ were proposed. In addition to researching the wavemaking response in a harbour, two joining methods in time domain were presented. The results indicate that the model and numerical methods are feasible.
基金supported by the Dong-A University of the Republic of Korea research fund。
文摘With the increasing demand for secure infrastructure such as hydrogen refueling stations,chemical plants,and energy storage systems,the need for protective structures capable of withstanding close-in detonations has become more critical.Existing design guidelines for protective walls(e.g.,UFC 3-340-02)primarily address mid-and far-field explosions,providing limited insights into near-field effects.Considering the effect of slight slopes(<40°)on reducing maximum reflected overpressure is deemed negligible.This study investigated the effectiveness of a reinforced concrete(RC)modular protection system(MPS)incorpo rating a diagonally tapered wall in attenuating re flected overpressures from closein detonations.Full-scale field experiments using a 51.3 kg TNT charge,representing the explosion energy of a typical hydrogen vessel rupture,demonstrated that a wall with a 7°slope significantly outperformed a vertical wall of equivalent concrete volume in terms of blast resistance.Observed structural responses included cracking,horizontal shear failure,and overturning.Complementary simulations using a validated computational fluid dynamics(CFD)model showed that the tapered wall reduced peak overpressure by 30%-40%compared to an equivalent vertical wall.This result highlights the potential of minor geometric modifications to enhance blast resilience.The tapered design effectively redirects incident blast waves,reducing localized damage while also conserving material,thus preserving modular benefits such as ease of transport and reusability.These findings suggest that diagonally tapered RC-based MPSs can offer a practical and resilient solution for industrial and military applications subject to near-field or sequential blast threats.
