Differences in Cross-Section Design Between Chinese and Foreign Standard Rails
What are the core section parameters of national standard 60kg/m rail?
The height of national standard 60kg/m rail is 176mm, which can ensure the vertical bending stiffness of the rail and meet the load requirements of conventional speed and intercity railways. Its rail head width is 73mm, and the wider rail head can increase the wheel-rail contact area and reduce the wear rate of the rail surface. The rail waist thickness is set at 20mm, which can balance the lightweight and anti-overturning ability of the rail and avoid increasing the overall self-weight due to excessive thickness. The rail base width is 150mm, and the wide rail base can improve the contact stability between the rail and sleeper and reduce the risk of local crushing of the sleeper. In addition, the centroid height of its section is controlled at about 90mm, which can optimize the stress transmission path of the rail and reduce the probability of deformation during long-term service.
What are the section differences between European standard 60E1 rail and national standard 60kg/m rail?
The rail head width of European standard 60E1 rail is 75mm, 2mm wider than the national standard, which can better adapt to the wheel set size of European trains and improve wheel-rail adaptability. Its rail waist thickness is 16.5mm, thinner than the national standard, which can reduce the self-weight of the rail on the premise of meeting the strength and lower the laying cost. The rail base width is 155mm, slightly wider than the national standard, which can enhance the lateral limit effect of the rail on the ballastless track. The arc radius of the rail head of European standard rail is larger, which can reduce the wheel-rail contact stress and extend the contact fatigue life of the rail. At the same time, the section modulus distribution of its section is more inclined to the rail head area, and the bearing capacity of the wheel-rail contact part is strengthened in a targeted way.
Why does the section design of American standard rail focus on thickening the rail base?
American standard rail often needs to adapt to heavy-haul freight trains with large axle loads. Thickening the rail base can increase the contact area between the rail and sleeper and disperse the local pressure of the sleeper. Some American lines use wooden sleepers, and thickening the rail base can prevent the rail from pressing into the wooden sleeper and ensure the long-term geometric smoothness of the track. Thickening the rail base can also enhance the anti-pulling ability of the rail, especially in the ramp section, which can resist the longitudinal tension generated when the train is traction. The maintenance cycle of American standard lines is long, and thickening the rail base can reduce the replacement frequency of the rail due to rail base wear and reduce the operation and maintenance investment. In addition, thickening the rail base can improve the overall stability of the rail and adapt to the large curve radius working conditions of some American lines.
What are the key points of lightweight section design of Japanese standard rail?
The rail waist of Japanese standard rail adopts a gradient thickness design, which gradually thins from the rail head to the rail base, ensuring both rail head bearing and reducing rail base self-weight. Its rail head adopts a narrowing design, and the rail head width is generally 3-5mm smaller than the national standard, which is suitable for the small wheel diameter wheel sets of Japanese trains and reduces the friction resistance of wheel-rail contact. The edge of the rail base is treated with arc transition to reduce the stress concentration between the rail base and the pad and improve the service life of the pad. The section hollow ratio of Japanese standard rail is slightly higher than that of the national standard, which further optimizes the self-weight while ensuring the strength, adapting to the light transportation demand in mountainous areas of Japan. At the same time, the bending stiffness distribution of its section is more balanced, which can adapt to the alternating load of high-frequency start and stop of urban rail.
What special optimizations should be made to the section of rails in alpine regions?
The rail waist of rails in alpine regions should be appropriately thickened by 1-2mm to enhance the low-temperature brittle fracture resistance of the rail and resist the lateral stress caused by frost heave. The rail head surface needs to be added with a wear-resistant alloy layer. Because the lubrication effect between wheel and rail is poor in alpine regions, thickening the wear-resistant layer can reduce rail wear. The part of the rail base in contact with the pad needs to be roughened to prevent rail slippage caused by permafrost freeze-thaw and ensure track geometric stability. The centroid position of its section should be adjusted slightly downward to improve the anti-overturning ability of the rail and cope with the uneven settlement of the track foundation in alpine regions. In addition, the arc radius of the section transition area of the rail should be increased to avoid cracks due to stress concentration at low temperatures.