The present study numerically explored the aerodynamic performance of a novel railway tunnel with a partially reduced cross-section.The impact of the reduction rate of the tunnel cross-section on wave transmissions wa...The present study numerically explored the aerodynamic performance of a novel railway tunnel with a partially reduced cross-section.The impact of the reduction rate of the tunnel cross-section on wave transmissions was analyzed based on the three-dimensional,unsteady,compressible,and RNG k-εturbulence model.The results highlight that the reduction rate(S)most affects pressure configurations at the middle tunnel segment,followed by the enlarged segments near access,and finally the exit.The strength of the newly generated compression wave at the tunnel junction where the cross-section abruptly changes increases exponentially with the decrease of the cross-sectional area.The maximum peak-to-peak pressureΔP on the tunnel and train surface for non-uniform tunnels is reduced by 10.7%and 13.8%,respectively,compared with those of equivalent uniform tunnels.Overall,the economic analysis suggests that the aerodynamic performance of the developed tunnel prototype surpasses those conventional tunnels based on the same excavated volume.展开更多
Recently based in the performance of tunnels under seismic movements a good progress is made in the seismic design of tunnels. The majority of problems in the tunnel structures take place in near fault conditions and ...Recently based in the performance of tunnels under seismic movements a good progress is made in the seismic design of tunnels. The majority of problems in the tunnel structures take place in near fault conditions and in the case of great variation of rock properties. Not having a previous experience in the seismic design of the tunnels that pass through tectonic zones with very large heterogeneity （strong rock-soil or very poor rock that behaves like soil） this article presents the general aspects of seismic calculation of tunnels and application in a specific example. The article presents the methods of seismic input modeling, design and particularities of numerical calculations. The geological conditions in which the case study tunnel will be constructed are very common in Albanian territory and represent one of the most difficult cases for the construction of road tunnels. The applied approach for using the longitudinal models for generating time histories of acceleration that can be used as input for transversal models is very simple and will help the designers for the seismic analysis of other tunnels that will be constructed in Albania.展开更多
基金Project(51975591)supported by the National Natural Science Foundation of China。
文摘The present study numerically explored the aerodynamic performance of a novel railway tunnel with a partially reduced cross-section.The impact of the reduction rate of the tunnel cross-section on wave transmissions was analyzed based on the three-dimensional,unsteady,compressible,and RNG k-εturbulence model.The results highlight that the reduction rate(S)most affects pressure configurations at the middle tunnel segment,followed by the enlarged segments near access,and finally the exit.The strength of the newly generated compression wave at the tunnel junction where the cross-section abruptly changes increases exponentially with the decrease of the cross-sectional area.The maximum peak-to-peak pressureΔP on the tunnel and train surface for non-uniform tunnels is reduced by 10.7%and 13.8%,respectively,compared with those of equivalent uniform tunnels.Overall,the economic analysis suggests that the aerodynamic performance of the developed tunnel prototype surpasses those conventional tunnels based on the same excavated volume.
文摘Recently based in the performance of tunnels under seismic movements a good progress is made in the seismic design of tunnels. The majority of problems in the tunnel structures take place in near fault conditions and in the case of great variation of rock properties. Not having a previous experience in the seismic design of the tunnels that pass through tectonic zones with very large heterogeneity （strong rock-soil or very poor rock that behaves like soil） this article presents the general aspects of seismic calculation of tunnels and application in a specific example. The article presents the methods of seismic input modeling, design and particularities of numerical calculations. The geological conditions in which the case study tunnel will be constructed are very common in Albanian territory and represent one of the most difficult cases for the construction of road tunnels. The applied approach for using the longitudinal models for generating time histories of acceleration that can be used as input for transversal models is very simple and will help the designers for the seismic analysis of other tunnels that will be constructed in Albania.
