The transient pressures induced by trains passing through a tunnel and their impact on the structural safety of the tunnel lining were numerically analyzed.The results show that the pressure change increases rapidly a...The transient pressures induced by trains passing through a tunnel and their impact on the structural safety of the tunnel lining were numerically analyzed.The results show that the pressure change increases rapidly along the tunnel length,and the maximum value is observed at around 200 m from the entrance,while the maximum pressure amplitude is detected at 250 m from the entrance when two trains meeting in a double-track tunnel.The maximum peak pressure on the tunnel induced by a train passing through a 70 m^(2) single-track tunnel,100 m^(2) double-track tunnel and two trains meeting in the 100 m^(2) double-track tunnel at 350 km/h,are−4544 Pa,−3137 Pa and−5909 Pa,respectively.The aerodynamic pressure induced axial forces acting on the tunnel lining are only 8%,5%and 9%,respectively,of those generated by the earth pressure.It seems that the aerodynamic loads exert little underlying influence on the static strength safety of the tunnel lining providing that the existing cracks and defects are not considered.展开更多
Provided the results of a research conducted to investigate the relationships between the empirical vibration attenuation equation of Peak Particle Velocity （PPV） and the Scaled Charge （SC） through testing the bla...Provided the results of a research conducted to investigate the relationships between the empirical vibration attenuation equation of Peak Particle Velocity （PPV） and the Scaled Charge （SC） through testing the blasting-induced vibrations on the spot of Wanshishan tunnel based on 96 vibration recordings. It is found that the maximum charge amount per delay in Wanshishan tunnel excavating is determined by the buildings on the surface and the constructed tunnel nearby. Considering that the repeated blast loading in tunnel blasting caused accumulative effects of damage on buildings, comfortable threshold damage limits of PPV to maintain buildings safety was given. Dynamic Stress Ratio （DSR） was adopted to study the stability of constructed tunnel on the action of blasting induced vibrations. The method to determine specific maximum charge amount per delay in Wanshishan tunnel excavation was given. It is proved that the findings in this study are very effective to control the negative effects of blasting-induced vibrations on buildings on the surface and constructed tunnel nearby.展开更多
This paper presents an overview of the safety performance of the major existing pipeline transmission system in Canada, USA and Europe. The article deals the experience of Georgia in the development of pipeline transp...This paper presents an overview of the safety performance of the major existing pipeline transmission system in Canada, USA and Europe. The article deals the experience of Georgia in the development of pipeline transport. The information on the distribution of catastrophic failures and incidents per individual cause is given. The role of corrosion in these failures is considered. To ensure efficient and reliable operations of oil and gas pipelines, the new compositions of competitive cost effective protective pipe enamel coatings have been developed.展开更多
Purpose： As trauma is a public health problem, different programs have been designed to prevent in- juries. The aim of this study was to evaluate the effectiveness of an educational model that measures the adolescent...Purpose： As trauma is a public health problem, different programs have been designed to prevent in- juries. The aim of this study was to evaluate the effectiveness of an educational model that measures the adolescents＇ attitudes towards the rules of road safety, alcohol and road accidents in Colombia. Methods： A pedagogical model evaluating the effect of road safety education and adolescents＇ attitudes towards and experiences of alcohol and road accidents in Colombia was created. After the education concluded, this educational process is analyzed by its impact on adolescents＇ behavior. The educational program included 160 adolescents with the mean age being 1Z5 years. Results： The test results indicated that before the educational program 80g of adolescents did not use a safety element when driving, while after the educational program the percentage of no helmet use among adolescents decreased from 72.5% to 24.3% （p = 0.0001 ） and driving a vehicle under the state of drunkenness from 49.3% to 8.1% （p = 0.0001）. Conclusion： An educational model aimed at preventing injuries caused by traffic accidents is shown to be effective in generating changes in adolescents＇ customs of and attitudes towards alcohol and road safety standards in Colombia.展开更多
基金Project(51975591)supported by the National Natural Science Foundation of ChinaProject(P2018J003)supported by the Technology Research and Development Program of China Railway。
文摘The transient pressures induced by trains passing through a tunnel and their impact on the structural safety of the tunnel lining were numerically analyzed.The results show that the pressure change increases rapidly along the tunnel length,and the maximum value is observed at around 200 m from the entrance,while the maximum pressure amplitude is detected at 250 m from the entrance when two trains meeting in a double-track tunnel.The maximum peak pressure on the tunnel induced by a train passing through a 70 m^(2) single-track tunnel,100 m^(2) double-track tunnel and two trains meeting in the 100 m^(2) double-track tunnel at 350 km/h,are−4544 Pa,−3137 Pa and−5909 Pa,respectively.The aerodynamic pressure induced axial forces acting on the tunnel lining are only 8%,5%and 9%,respectively,of those generated by the earth pressure.It seems that the aerodynamic loads exert little underlying influence on the static strength safety of the tunnel lining providing that the existing cracks and defects are not considered.
基金Supported by the National Natural Science Foundation of China（50974059）
文摘Provided the results of a research conducted to investigate the relationships between the empirical vibration attenuation equation of Peak Particle Velocity （PPV） and the Scaled Charge （SC） through testing the blasting-induced vibrations on the spot of Wanshishan tunnel based on 96 vibration recordings. It is found that the maximum charge amount per delay in Wanshishan tunnel excavating is determined by the buildings on the surface and the constructed tunnel nearby. Considering that the repeated blast loading in tunnel blasting caused accumulative effects of damage on buildings, comfortable threshold damage limits of PPV to maintain buildings safety was given. Dynamic Stress Ratio （DSR） was adopted to study the stability of constructed tunnel on the action of blasting induced vibrations. The method to determine specific maximum charge amount per delay in Wanshishan tunnel excavation was given. It is proved that the findings in this study are very effective to control the negative effects of blasting-induced vibrations on buildings on the surface and constructed tunnel nearby.
文摘This paper presents an overview of the safety performance of the major existing pipeline transmission system in Canada, USA and Europe. The article deals the experience of Georgia in the development of pipeline transport. The information on the distribution of catastrophic failures and incidents per individual cause is given. The role of corrosion in these failures is considered. To ensure efficient and reliable operations of oil and gas pipelines, the new compositions of competitive cost effective protective pipe enamel coatings have been developed.
文摘Purpose： As trauma is a public health problem, different programs have been designed to prevent in- juries. The aim of this study was to evaluate the effectiveness of an educational model that measures the adolescents＇ attitudes towards the rules of road safety, alcohol and road accidents in Colombia. Methods： A pedagogical model evaluating the effect of road safety education and adolescents＇ attitudes towards and experiences of alcohol and road accidents in Colombia was created. After the education concluded, this educational process is analyzed by its impact on adolescents＇ behavior. The educational program included 160 adolescents with the mean age being 1Z5 years. Results： The test results indicated that before the educational program 80g of adolescents did not use a safety element when driving, while after the educational program the percentage of no helmet use among adolescents decreased from 72.5% to 24.3% （p = 0.0001 ） and driving a vehicle under the state of drunkenness from 49.3% to 8.1% （p = 0.0001）. Conclusion： An educational model aimed at preventing injuries caused by traffic accidents is shown to be effective in generating changes in adolescents＇ customs of and attitudes towards alcohol and road safety standards in Colombia.
