Residents living near drill-and-blast tunnels often experience disturbances from blasting operations.This motivates us to investigate the characteristics of airblasts and resulting noise through on-site monitoring at ...Residents living near drill-and-blast tunnels often experience disturbances from blasting operations.This motivates us to investigate the characteristics of airblasts and resulting noise through on-site monitoring at three tunnels.The research focuses on both the temporal evolution and spatial propagation of airblasts.Temporal analysis,including peak overpressure(POp),positive duration(PD),and Fourier main frequency(MF),emphasizes the relationship between airblast characteristics,blasting delays,and rock grade.It shows that airblast bandwidths are typically in the range of 3e200 Hz,with noise levels exceeding 130 dB,which is comparable to jet engines and rocket launch.Spatial propagation analysis reveals the impact of tunnel space on airblast propagation.Although POp and PD typically decrease with distance inside the tunnel,wave superposition can cause increased overpressure and prolonged durations at far-field distances(above 60 m kg^(-1/3)).Outside the tunnel,sound radiation was influenced by azimuth and was basically determined by sound power d an often-overlooked factor.To address the anisotropic propagation of airblasts,a predictive model was proposed for external noise levels,considering variables like distance,azimuth angle,initial sound power,and wave expansion.Validated by tests,this model successfully unifies data from three studies,helping to explain and predict airblast disturbances near tunnels.展开更多
The significance of studying, monitoring and predicting blast induced vibration and noise level in mining and civil activities is justified in the capability of imposing damages, sense of uncertainty due to negative p...The significance of studying, monitoring and predicting blast induced vibration and noise level in mining and civil activities is justified in the capability of imposing damages, sense of uncertainty due to negative psychological impacts on involved personnel and also judicial complaints of local inhabitants in the nearby area. This paper presents achieved results during an investigation carried out at Sungun Copper Mine, lran. Besides, the research also studied the significance of blast induced ground vibration and air- blast on safety aspects of nearby structures, potential risks, frequency analysis, and human response. According to the United States Bureau of Mines （USBM） standard, the attenuation equations were devel- oped using field records. A general frequency analysis and risk evaluation revealed that： 94% of generated frequencies are less than 14 Hz which is within the natural frequency of structures that increases risk of damage. At the end, studies of human response showed destructive effects of the phenomena by ranging between 2.54 and 25.40 mm/s for ground vibrations and by the average value of 110 dB for noise levels which could increase sense of uncertainty among involved employees.展开更多
The performance of multilayered thin steel plates subjected to close-range air blasts has been experimentally studied and compared with that of monolithic plates made of the same material and having equal mass. In pre...The performance of multilayered thin steel plates subjected to close-range air blasts has been experimentally studied and compared with that of monolithic plates made of the same material and having equal mass. In present experiments, multilayered plates are in-contact four-layered thin steel plates and two types of deformation/failure modes were observed for them. Comparisons concerning deformation/failure modes, strain distributions and energy absorptions between the multilayered plate and its monolithic counterpart were conducted. It is found that the multilayered plate is much superior to its monolithic counterpart in the ability to deform against blast loading. Furthermore, under intense airblast loading, the multilayered plate can not only absorb much more energy but also effectively reduce the secondary destruction ability of structural fragments in comparison with its monolithic counterpart.展开更多
Airblasts,as one common phenomenon accompanied by rapid movements of landslides or rock/snow avalanches,commonly result in catastrophic damages and are attracting more and more scientific attention.To quantitatively a...Airblasts,as one common phenomenon accompanied by rapid movements of landslides or rock/snow avalanches,commonly result in catastrophic damages and are attracting more and more scientific attention.To quantitatively analyze the intensity of airblast initiated by landslides,the Wangjiayan landslide,occurred in the Wenchuan earthquake,is selected here with the landslide propagation and airblast evolution being studied using FLUENT by introducing the Voellmy rheological law.The results reveal that:(1)For the Wangjiayan landslide,its whole travelling duration is only 12 s with its maximum velocity reaching 36 m/s at t=10 s;(2)corresponding to the landslide propagation,the maximum velocity,28 m/s,of the airblast initiated by the landslide also appears at t=10 s with its maximum pressure reaching594.8 Pa,which is equivalent to violent storm;(3)under the attack of airblast,the load suffered by buildings in the airblast zone increases to 1300 Pa at t=9.4 s and sharply decreased to-7000 Pa as the rapid decrease of the velocity of the sliding mass at t=10 s,which is seriously unfavorable for buildings and might be the key reason for the destructive collapse of buildings in the airblast zone of the Wangjiayan landslide.展开更多
Impacts of airblast and vibrations arise from blasting, a dangerous activity if not designed and performed to standard. This paper evaluates airblast and ground vibration levels and its potential impact on the neighbo...Impacts of airblast and vibrations arise from blasting, a dangerous activity if not designed and performed to standard. This paper evaluates airblast and ground vibration levels and its potential impact on the neighbouring communities. Two calibrated seismographs were used to monitor potential airblast and ground vibration generated from the blast at Chimiwungo Pit. The blast complied with the set limits for infrastructures and slopes monitoring. Vibrations recorded from the trial shot PPV were predicted at 2.46 mm/s and Airblast of 10 mm/s with a maximum of 134 dB at the mine boundary, all remained well below accepted industry standards and guidelines. The airblast and ground vibration levels monitored and recorded were considered to be normal for surface blasting operations and had no negative impact on the nearby township of Manyama.展开更多
由于加压工作条件下雾化粒径数据的稀缺以及基于物理机制粒径预测模型的缺乏,本文开展了加压工作条件下预膜空气雾化喷嘴燃油粒径预测模型研究。通过试验设计(Design of Experiment,DOE),采用激光粒度仪测试了空气压力、空气温度、空气...由于加压工作条件下雾化粒径数据的稀缺以及基于物理机制粒径预测模型的缺乏,本文开展了加压工作条件下预膜空气雾化喷嘴燃油粒径预测模型研究。通过试验设计(Design of Experiment,DOE),采用激光粒度仪测试了空气压力、空气温度、空气压降、燃油温度、油气比等多参数交叉影响下的雾化粒径数据,基于表面波不稳定理论构建了包含韦伯数、雷诺数、奥内佐格数等无量纲参数的预测模型。通过试验数据的验证,发现预测模型最大误差为14.1%,平均误差为5.2%,且残差符合正态分布。敏感性分析表明,预测模型准确捕捉了无量纲参数以及试验工况参数对粒径的影响。展开更多
基金supported by the Shenzhen Stability Support Plan(Grant No.20231122095154003)National Natural Science Foundation of China(Grant Nos.51978671 and 52422807).
文摘Residents living near drill-and-blast tunnels often experience disturbances from blasting operations.This motivates us to investigate the characteristics of airblasts and resulting noise through on-site monitoring at three tunnels.The research focuses on both the temporal evolution and spatial propagation of airblasts.Temporal analysis,including peak overpressure(POp),positive duration(PD),and Fourier main frequency(MF),emphasizes the relationship between airblast characteristics,blasting delays,and rock grade.It shows that airblast bandwidths are typically in the range of 3e200 Hz,with noise levels exceeding 130 dB,which is comparable to jet engines and rocket launch.Spatial propagation analysis reveals the impact of tunnel space on airblast propagation.Although POp and PD typically decrease with distance inside the tunnel,wave superposition can cause increased overpressure and prolonged durations at far-field distances(above 60 m kg^(-1/3)).Outside the tunnel,sound radiation was influenced by azimuth and was basically determined by sound power d an often-overlooked factor.To address the anisotropic propagation of airblasts,a predictive model was proposed for external noise levels,considering variables like distance,azimuth angle,initial sound power,and wave expansion.Validated by tests,this model successfully unifies data from three studies,helping to explain and predict airblast disturbances near tunnels.
文摘The significance of studying, monitoring and predicting blast induced vibration and noise level in mining and civil activities is justified in the capability of imposing damages, sense of uncertainty due to negative psychological impacts on involved personnel and also judicial complaints of local inhabitants in the nearby area. This paper presents achieved results during an investigation carried out at Sungun Copper Mine, lran. Besides, the research also studied the significance of blast induced ground vibration and air- blast on safety aspects of nearby structures, potential risks, frequency analysis, and human response. According to the United States Bureau of Mines （USBM） standard, the attenuation equations were devel- oped using field records. A general frequency analysis and risk evaluation revealed that： 94% of generated frequencies are less than 14 Hz which is within the natural frequency of structures that increases risk of damage. At the end, studies of human response showed destructive effects of the phenomena by ranging between 2.54 and 25.40 mm/s for ground vibrations and by the average value of 110 dB for noise levels which could increase sense of uncertainty among involved employees.
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 51179200 and 51209211)the Innovation Research Foundation for Ph. D Candidates of Naval University of Engineering, China (Grant No. HGYJSJJ2012001)
文摘The performance of multilayered thin steel plates subjected to close-range air blasts has been experimentally studied and compared with that of monolithic plates made of the same material and having equal mass. In present experiments, multilayered plates are in-contact four-layered thin steel plates and two types of deformation/failure modes were observed for them. Comparisons concerning deformation/failure modes, strain distributions and energy absorptions between the multilayered plate and its monolithic counterpart were conducted. It is found that the multilayered plate is much superior to its monolithic counterpart in the ability to deform against blast loading. Furthermore, under intense airblast loading, the multilayered plate can not only absorb much more energy but also effectively reduce the secondary destruction ability of structural fragments in comparison with its monolithic counterpart.
基金supported by the National Natural Science Foundation of China(42322702,42177131)。
文摘Airblasts,as one common phenomenon accompanied by rapid movements of landslides or rock/snow avalanches,commonly result in catastrophic damages and are attracting more and more scientific attention.To quantitatively analyze the intensity of airblast initiated by landslides,the Wangjiayan landslide,occurred in the Wenchuan earthquake,is selected here with the landslide propagation and airblast evolution being studied using FLUENT by introducing the Voellmy rheological law.The results reveal that:(1)For the Wangjiayan landslide,its whole travelling duration is only 12 s with its maximum velocity reaching 36 m/s at t=10 s;(2)corresponding to the landslide propagation,the maximum velocity,28 m/s,of the airblast initiated by the landslide also appears at t=10 s with its maximum pressure reaching594.8 Pa,which is equivalent to violent storm;(3)under the attack of airblast,the load suffered by buildings in the airblast zone increases to 1300 Pa at t=9.4 s and sharply decreased to-7000 Pa as the rapid decrease of the velocity of the sliding mass at t=10 s,which is seriously unfavorable for buildings and might be the key reason for the destructive collapse of buildings in the airblast zone of the Wangjiayan landslide.
文摘Impacts of airblast and vibrations arise from blasting, a dangerous activity if not designed and performed to standard. This paper evaluates airblast and ground vibration levels and its potential impact on the neighbouring communities. Two calibrated seismographs were used to monitor potential airblast and ground vibration generated from the blast at Chimiwungo Pit. The blast complied with the set limits for infrastructures and slopes monitoring. Vibrations recorded from the trial shot PPV were predicted at 2.46 mm/s and Airblast of 10 mm/s with a maximum of 134 dB at the mine boundary, all remained well below accepted industry standards and guidelines. The airblast and ground vibration levels monitored and recorded were considered to be normal for surface blasting operations and had no negative impact on the nearby township of Manyama.
文摘由于加压工作条件下雾化粒径数据的稀缺以及基于物理机制粒径预测模型的缺乏,本文开展了加压工作条件下预膜空气雾化喷嘴燃油粒径预测模型研究。通过试验设计(Design of Experiment,DOE),采用激光粒度仪测试了空气压力、空气温度、空气压降、燃油温度、油气比等多参数交叉影响下的雾化粒径数据,基于表面波不稳定理论构建了包含韦伯数、雷诺数、奥内佐格数等无量纲参数的预测模型。通过试验数据的验证,发现预测模型最大误差为14.1%,平均误差为5.2%,且残差符合正态分布。敏感性分析表明,预测模型准确捕捉了无量纲参数以及试验工况参数对粒径的影响。
