BASF and Sinopec began the construction for the expansion of their joint venture,BASF-YPC Co.,Ltd. (BYC). BASF and Sinopec plan to jointly invest approximately $1.4 billion
The complex bridge-track interaction between kilometer-span bridges and continuous Welded Rail(CWR)brings great challenges to CWR designing.Taking a suspension bridge with laying CWR as a case,the mechanical propertie...The complex bridge-track interaction between kilometer-span bridges and continuous Welded Rail(CWR)brings great challenges to CWR designing.Taking a suspension bridge with laying CWR as a case,the mechanical properties of CWR on the bridge are analyzed to reveal the sensitive areas of the track,and the design method of CWR and track structures on the beam ends are proposed.The results show that the unidirectional Rail Expansion Joints(REJ)need to be installed on the beam end of the kilometer-span bridge to reduce rail longitudinal force.Due to the bridge characteristics,there is no CWR fixed area on the kilometer-span bridge,and rail longitudinal force on the main span caused by bending loads needs to be concerned.The deformation of track on the beam end is complex,which is the weak area on the kilometer bridge,the large relative displacement between the stock rail of REJ and the main beam can cause poor stability of ballast bed on beam end,small resistance fasteners need to be laid on the sides of stock rail on the main beam to increase the stability of ballast and fasteners on the beam end.To improve the driving safety and comfort of beam end,the Sleeper-Supporting Apparatus(SSA)should be specially designed to ensure the uniform transition of track on beam ends.Temperature and wind loads have a significant impact on track regularity on the kilometer span bridge,the dynamic response of trains and bridges under those loads needs to be attended to.展开更多
Stress concentration occurs in the foundations of railway tracks where discontinuous components are located.The exacerbated stress under the expansion joints in slab tracks may trigger foundation failures such as mud ...Stress concentration occurs in the foundations of railway tracks where discontinuous components are located.The exacerbated stress under the expansion joints in slab tracks may trigger foundation failures such as mud pumping.Although the higher stress due to the discontinuities of track structures has been discussed in past studies,few focused on the stress response of roadbeds in slab tracks and quantitatively characterized the stress pattern.In this paper,we performed a dynamic finite element analysis of a track-formation system,incorporating expansion joints as primary longitudinal discontinuities.The configurations of CRTS Ⅲ slab tracks and the contact conditions between concrete layers were considered.Numerical results show that longitudinal influencing length of induced stress on roadbed under wheel load relates to the contact conditions between concrete layers,increasing nonlinearly at a larger coefficient of friction.Given a measured coefficient of friction of 0.7,the calculated longitudinal influencing length(9.0 m) matches with field data.The longitudinal influencing length is not affected with the increasing velocity.As stress concentration arises with expansion joints,the worstcase scenario emerges when double-axle loads are exerted immediately above the expansion joints between concrete bases.A stress concentration factor Cvon the roadbed is proposed;it increases with the increasing velocity,changing from 1.33 to 1.52 at velocities between 5 and 400 km/h.The stress distribution on roadbeds transforms from a trapezoid pattern at continuous sections to a triangle pattern at points with longitudinal discontinuities.An explicit expression is finally proposed for the stress pattern on roadbed under expansion joints.Although structural discontinuities induce stress raiser,the extent of concentration is mitigated with increasing depth at different velocity levels.展开更多
文摘BASF and Sinopec began the construction for the expansion of their joint venture,BASF-YPC Co.,Ltd. (BYC). BASF and Sinopec plan to jointly invest approximately $1.4 billion
基金supported by the National Key R&D Program of China(2022YFB2602901)the National Natural Science Foundation of China(No.52178405).
文摘The complex bridge-track interaction between kilometer-span bridges and continuous Welded Rail(CWR)brings great challenges to CWR designing.Taking a suspension bridge with laying CWR as a case,the mechanical properties of CWR on the bridge are analyzed to reveal the sensitive areas of the track,and the design method of CWR and track structures on the beam ends are proposed.The results show that the unidirectional Rail Expansion Joints(REJ)need to be installed on the beam end of the kilometer-span bridge to reduce rail longitudinal force.Due to the bridge characteristics,there is no CWR fixed area on the kilometer-span bridge,and rail longitudinal force on the main span caused by bending loads needs to be concerned.The deformation of track on the beam end is complex,which is the weak area on the kilometer bridge,the large relative displacement between the stock rail of REJ and the main beam can cause poor stability of ballast bed on beam end,small resistance fasteners need to be laid on the sides of stock rail on the main beam to increase the stability of ballast and fasteners on the beam end.To improve the driving safety and comfort of beam end,the Sleeper-Supporting Apparatus(SSA)should be specially designed to ensure the uniform transition of track on beam ends.Temperature and wind loads have a significant impact on track regularity on the kilometer span bridge,the dynamic response of trains and bridges under those loads needs to be attended to.
基金This work was supported by the National Natural Science Foundation of China(Nos.41901073 and 52078435)the Sichuan Science and Technology Program(No.2021YJ0001)。
文摘Stress concentration occurs in the foundations of railway tracks where discontinuous components are located.The exacerbated stress under the expansion joints in slab tracks may trigger foundation failures such as mud pumping.Although the higher stress due to the discontinuities of track structures has been discussed in past studies,few focused on the stress response of roadbeds in slab tracks and quantitatively characterized the stress pattern.In this paper,we performed a dynamic finite element analysis of a track-formation system,incorporating expansion joints as primary longitudinal discontinuities.The configurations of CRTS Ⅲ slab tracks and the contact conditions between concrete layers were considered.Numerical results show that longitudinal influencing length of induced stress on roadbed under wheel load relates to the contact conditions between concrete layers,increasing nonlinearly at a larger coefficient of friction.Given a measured coefficient of friction of 0.7,the calculated longitudinal influencing length(9.0 m) matches with field data.The longitudinal influencing length is not affected with the increasing velocity.As stress concentration arises with expansion joints,the worstcase scenario emerges when double-axle loads are exerted immediately above the expansion joints between concrete bases.A stress concentration factor Cvon the roadbed is proposed;it increases with the increasing velocity,changing from 1.33 to 1.52 at velocities between 5 and 400 km/h.The stress distribution on roadbeds transforms from a trapezoid pattern at continuous sections to a triangle pattern at points with longitudinal discontinuities.An explicit expression is finally proposed for the stress pattern on roadbed under expansion joints.Although structural discontinuities induce stress raiser,the extent of concentration is mitigated with increasing depth at different velocity levels.
