1 Introduction

With the evolution of climate change, the thermal transfer effects of ballastless track in high-speed railways under complicated environmental conditions becomes increasingly important, governed by a number of meteorological factors, including solar radiation, ambient temperature, wind speed and direction, humidity, and many others [1]. Because these meteorological factors are highly site-specific, the huge area traversed by high-speed railway in China is affected by varying meteorological conditions that could have a significant effect on the mechanical behavior of track–bridge systems. The China Railway Track System type II (CRTS II) is a typical ballastless slab track for high-speed railway systems. In order to guarantee good structural performance for long-term operation, it is necessary to study the influence of meteorological conditions on the thermal transfer effects of CRTS II track.

In recent years, more and more researchers have studied the temperature field and the CRTS II track based on monitoring of field data. Dai et al. [2] and Huang et al. [3] investigated the temperature distribution characteristics of the CRTS II track using conventional statistical methods, while Yang et al. [4] and Song et al. [5] revealed the relationship between meteorological factors and the internal temperature of the CRTS II track through finite element models analysis. Using temperature tests of scaled models, Cai et al. [6] and Zhou et al. [7] investigated the influence of cyclic and overall temperature on the displacement, strain, and temperature field of a scaled CRTS II track–bridge structure. Furthermore, Zhu et al. [8] and Zhang et al. [9] explored interfacial damage development of CRTS II track under complex temperature conditions in a cohesive zone model (CZM) and concrete damaged plasticity model. In addition, Zhou et al. [10,11,12] studied the mechanical behavior of CRTS II track under the coupling effect of train and environment loads.

2 Meteorological Parameter Collection

Using a typical zone of CRTS II track on a bridge in the Beijing–Shanghai high-speed railway system as a case study, the meteorological data and internal temperature of the track structure were collected for 6 months. The relationships between ambient temperature and the temperature at the midspan and end of the bridge are depicted in Fig. 1, and the relationships among four meteorological parameters (temperature, solar radiation, wind speed, humidity) were also investigated. The change in the temperature within the track structure obviously lagged behind the change in the ambient temperature, and the temperature variation was smaller than that of the ambient temperature. Furthermore, Pearson correlation analysis showed a strong positive correlation between the ambient temperature and solar radiation, with a Pearson correlation coefficient of 0.85, while the correlation coefficient of 0.22 between the ambient temperature and air humidity was the smallest.

Fig. 1
3 images. A. A graph of temperature in degrees Celsius versus time in hours for the end, midspan 1, midspan 2, and air temperature. B. A wind rose diagram indicates the directions of wind and winter. C. A matrix with 4 columns and 4 rows depicts solar radiation, temperature, humidity, and wind speed.

Four meteorological parameters evaluated

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3 Heart Transfer Model

Based on the finite element (FE) software of Comsol, the heat transfer numerical models of CRTS II track on a simply-supported box bridge were established (Fig. 2a). The total dimensions of the five slab tracks were 32 m length × 13.4 m width × 3.35 m height, and the track slab, the CAM layer, base plate and box girder were simulated by the solid elements. Two ends of the slab tracks were constrained, and the thermal responses of the track structure under the four meteorological parameters were compared. As shown in Fig. 2b, c, the internal temperature and vertical displacement at the mid-span of the slab tracks become larger with increasing wind speed or solar radiation, especially for wind speeds >6 m/s or solar radiation >750 W/m2. According to the 3D temperature and stress field shown in Fig. 2d–f, increasing solar radiation or ambient temperature could lead to rapid heat transfer from the slab track to the base plate. The role of wind speed on the heat transfer effect in the track structure was limited.

Fig. 2
A. Diagram of F E model of a simply-supported box bridge. B and C. 2 Line graphs of the temperature of the track slab and the vertical displacement of the track slab versus wind speed and solar radiation. D, E, and F. Representation of fields of temperature and stress.

Thermal responses comparison under meteorological parameters: a FE model; b, c temperature and displacement responses under various wind speeds and solar radiation levels; d, e temperature field under 1100 W/m2 solar radiation; f stress field under 1100 W/m2 solar radiation

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4 Conclusions

Based on the combination of field measurement data and FE analysis, the thermal transfer effects in a CRTS II slab track–bridge system under various meteorological conditions were studied. The major findings were:

  1. (1)

    Three meteorological conditions—ambient temperature, solar radiation, and wind speed—had large correlation coefficients, showing they had the greatest influence on thermal transfer in the track structure.

  2. (2)

    Increasing solar radiation or ambient temperature could lead to increasing deformation and longitudinal stress of the slab track structure, but only wind speeds >6 m/s affected thermal transfer in the track structure.