The Principle of High-speed Rail Seamless Rail

Edit:Zongxiang Heavy Industry--Elina Date:2021-11-09 14:05:31

In recent years, with the rapid development of high-speed and heavy-duty railways, the track structure has gradually been replaced by ordinary lines by seamless lines. Compared with ordinary lines, the seamless line eliminates a large number of rail joints in the factory, so it has the advantages of smooth running, low track maintenance costs, and long service life. It has become the main method of high-speed railway line construction at present.
Seamless steel rails, that is, super-long seamless steel rails, are not completely free of gaps, but the number of gaps in the entire railway section is so small that it is almost negligible. Under normal circumstances, it is formed by welding multiple short rails in sequence. When the wheel reaches the seam of the two rails, part of the wheel tread is pressed on the first rail, and the other part of the wheel tread is pressed on the second rail at the same time, so that the two steel rails are stressed at the same time, so that the wheel Smoothly pass through the joint between the two steel rails without vibration.

In the past, in order to take into account the thermal expansion and contraction of the track, expansion joints were left between each track, which is what we have seen in conventional railway tracks. For high-speed railways, traditional steel rails connection methods cannot be used. Seamless track is the basic requirement of high-speed railway. Seamless track is not a track without joints. Its length is often hundreds to thousands of kilometers, which is impossible to achieve. The seamless track is also welded by a single track, but a special welding machine is used. In order to overcome thermal expansion and contraction, the rail must be pre-stressed. Pre-stressed stretching is a modern new technology. After the pre-stressed stretching treatment, the thermal expansion and contraction caused by the temperature change can be offset, so that the large length does not need the expansion joint. Seamless track is also called pre-stressed (tensile) track. Pre-stressed stretch is not only used for high-speed railways, for example, the steel cables on our common cable-stayed bridges also need to be pre-stressed to overcome the tension changes caused by the thermal expansion and contraction of the steel cables.