# Experimental Research on the Load Transfer Mechanism of Tie Plates for 400 km/h High-Speed Turnouts
## 1 Introduction
An important aspect of high-speed turnout research and development is the performance optimization of the elastic iron tie plate in the turnout area. The stiffness of the track structure is an important parameter that affects the comfort of vehicle operation, track geometry, sleeper bed, and maintenance and repair workload. The turnout area connects many different rail parts, such as stock, switch, wing, and point rails, coupled with spacing blocks and other factors, and thus the track stiffness in this area is unevenly distributed longitudinally. From a large amount of measured data, it is known that the rail vertical dynamic displacement is 0.5-0.7 mm on the passenger-dedicated line turnout in China, while the rail vertical dynamic displacement is 0.9-1.0 mm in the CN turnout in Germany. The rail shows a vertical dynamic displacement of about 0.7 mm on the regular high-speed railway line in China [20, 21, 22, 23]. It can be seen that the passenger-dedicated line turnouts in China have higher track stiffness than those in Germany; in fact, the track stiffness in the turnout zone is even greater than that on the regular line in China. With an increase in the operating speed, the effects of track vibration and uneven stiffness caused by the larger stiffness will be further amplified. Therefore, for the 400 km/h high-speed turnout, the track stiffness in the turnout area should first be further examined. Scholars have carried out a series of research works in the study of track stiffness. [PERSON] et al. [24; 25] studied the distribution and homogenization of track stiffness in the turnout area of heavy haul railway. [PERSON] et al. [26] studied the identification of sleeper support conditions using a mechanical model supported data-driven approach. In addition, they [27; 28] explored the mechanism of sleep-ballast dynamic impact and residual settlements accumulation in zones with unsupported sleepers. [PERSON] et al. [29] analyzed the impact of the variable stiffness section on the conditions of track and rolling stock interaction. [PERSON] et al. [4] studied the mechanical wear contact between the wheel and rail on a turnout with variable stiffness. [PERSON] et al. [30] analyzed the dynamic train-track interactions over railway track stiffness transition zones using baseplate fastening systems. [PERSON] et al. [31; 32] discussed the approach to the stiffness homogenization of the No. 12 crossover turnout with integrated bed. [PERSON] et al. [33; 34; 35] analyzed the change rule of switching force of small-sized turnout with the change of closure section's stiffness. [PERSON] et al. [36; 37] explored the influence of track stiffness irregularity beneath turnout on the dynamic characteristics of the wheel-rail system. Track stiffness optimization in the turnout area mainly follows the following two principles: (1) the stiffness of the turnout area should remain consistent with that of the regular line as far as possible and (2) the stiffness of the turnout area should be distributed uniformly. Based on the dynamic test results and the current use status of existing high-speed turnouts, after systematic theoretical and experimental research, this research group proposes to reduce the target stiffness of the turnout area from 25 \(\pm\) 5 kN/mm to 22 \(\pm\) 3 kN/mm, taking into account the complex structures of rail parts and connections in the turnout area, and proposes the reduction of the stiffness values of  
* the front end of the switch rail from 25 kN/mm to 22 kN/mm;
* the slide plate section from 22.5 kN/mm to 21 kN/mm;
* the large and long spacing blocks at the heel of the switch rail from 20 kN/mm to 19 kN/mm;
* the lead curve section from 25 kN/mm to 22 kN/mm;
* the movable section of the point rail in the frog area from 22.5 kN/mm to 21 kN/mm;
* the large and long spacing blocks at the heel of the frog from 20 kN/mm to 19 kN/mm;
* the guard rail section from 25 kN/mm to 22 kN/mm; and
* the crossover track sections before and after the turnout from 25 kN/mm to 22 kN/mm.