Adaptability Analysis For Key Parameters Of Horizontal Curve From Existing Railway Operated For CRH2 High-speed Train

In the design of railway line,the layout of track in horizontal plane plays an important role,which becomes a key factor affecting the operation performance of high-speed trains on existing lines,as curve parameters are hardly to be modified after construction.Aiming at improving the transportation benefits of existing railways,it is of great significance to study the influence of curve parameters in terms of dynamic performance of the high-speed vehicle to ensure the safety and comfort of high-speed trains on existing lines.The adaptability of the key parameters of the horizontal curve for the high-speed train operated on the existing lines is studied,providing a theoretical reference for the engineering practice of the existing lines to enable the operation of the high-speed train.Considering the operation of the China Railway high-speed train,the CRH2 vehicle model was established based on the theory of multi-body system dynamics.Based on relevant design specifications and the track irregularity theory,the existing line plane conditions and track geometry were determined.Using the established the high-speed vehicle model,the safety and stability of the high-speed vehicle were simulated and analyzed respectively in different types of curve sections.The investigation involves several key parameters of the existing line,including the length of the curve transition,the cant deficiency,and the curve radius.The results show that the length of transition curve has limited effect on the dynamic performance of high-speed trains operation on the existing line.However,the cant deficiency of the curve is a key factor affecting the dynamic performance of high-speed vehicle.If the cant deficiency is basically unchanged,the curve radius of the existing line will have little effect on the dynamic performance of high-speed vehicle.When the length of the transition curve is sufficient and the cant deficiency reaches 100 mm,the safety indicators of the high-speed vehicle such as derailment coefficient,wheel load reduction rate,and lateral force of the wheel set meet the limit requirements.The stability index is always better than the limit value representing the excellent level.Taking the cant deficiency value of 100 mm as the standard,the running speed of the high-speed vehicle on some curves of mixed passenger and freight railway can be improved to a certain extent.In view of the special situation that some curves of the existing line are not set with transition curves,the dynamic performance of the high-speed vehicle on the curve without transition curve is calculated by the simulation.The results show that when the running speed of the curve without transition curve varies between 120 and 160km/h,the change trend of the safety and stability indicators of the high-speed vehicle is basically stable.When the running speed exceeds 160 km/h,the vertical acceleration increases,and the significant fluctuations occur.Based on the simulation results of the dynamic responses of the high-speed EMU under different cant,it is concluded that the cant of the curve without transition curve should not exceed 20 mm.On this basis,a scheme is proposed to increase the running speed of the high-speed train from 140 km/h to 160 km/h at the section without transition curve.Aiming at the reverse curve condition,as the most unfavorable condition from the existing line,the dynamic performance analysis of the high-speed vehicle is carried out.When the cant deficiency is defined as 60 mm and 100 mm respectively,the dynamic performance of the high-speed vehicle on the reverse curve section has no obvious change.In addition,regardless of the conventional reverse curve,the reverse curve without transition curve and the combined reverse curve,the dynamic response of the vehicle on the intermediate straight line does not exhibit obviously sudden change and shock.