At present, the jointless track used in high-speed rail is usually of temperature stress type, and 2~4 pairs of standard length rails are set between two long rail tracks to form a buffer zone. That is to say, the whole length of the rail is not seamless, there will be telescopic rails at a certain distance, or the rail will be welded and bonded, and there is a certain displacement space, which is not seamless.

The phenomenon that objects expand when heated and contract when cooled is common in nature. This is inevitable. Ordinary ballasted track is supported by ballast, but the ballast is loose and has good pressure absorption performance, but poor stability. The reserved rail interface is not only beneficial to thermal expansion and cold contraction, but also beneficial to dispersing pressure. It's just that the expansion joint at the interface needs to reserve the corresponding degree value when it expands with heat and contracts with cold, which causes waste to a great extent, and also increases the wear of rail and hub, leading to unstable driving and noise experience.

High-speed rail made corresponding countermeasures at the beginning of design. Ballastless track is prefabricated in the prefabrication factory according to the scientific scheme, which greatly improves the riding stability. Almost all tracks are welded super-long tracks, which greatly reduces the expansion joints of traditional rails. Therefore, it is necessary to redesign to solve the problem of thermal expansion and cold contraction. Generally speaking, we will collect data according to local meteorology and geology, and calculate the reasonable value of local average temperature, as well as the deformation of objects caused by thermal expansion and cold contraction. When the rail leaves the factory, we have reserved space for thermal expansion and cold contraction under the corresponding data such as average temperature, air pressure and precipitation.

When laying rails on ballastless track, tighten screws, buttons, plastic pads, etc. The rail will be locked on the sleeper plate, which is equivalent to using part of the force as the internal stress of the rail to offset the stress caused by thermal expansion and cold contraction, that is, forcing the rail not to deform. In addition, the rail waist will be perforated to release thermal expansion and cold contraction to avoid rail expansion. Observatories will also be set up on bridges and relatively stable road sections to effectively monitor deformation variable values, so as to take artificial measures to release energy in time.