Study on thermal regime of roadbed-culvert transition section along a high speed railway in seasonally frozen regions

- Thermal regime of Roadbed-Culvert Transition Section along the HDPDL has been investigated.
- The changing process of 0°C thermal line around the culvert has been investigated and simulation.
- The culvert weakening the temperature differences between two slope sides.
- We defined a coefficient like wetted perimeter, which was the shape-coefficient of the culvert.

Harbin to Dalian passenger dedicated line (HDPDL) was the first high-speed railway in the moderately deep seasonally frozen regions in the Northeast China. The roadbed-culvert transition section (RCTS) was paid special attention, as it was prone to uneven deformation. In this paper, the temperature field and its changing process of a typical RCTS at Siping site along HDPDL were discussed based on monitoring data. The results showed that during the freezing period (from November, 2010 to March, 2011), the thinner of the fill layer on the culvert, the higher temperature amplitude appeared in the RCTS. Due to the solar radiation difference on the sunny and shady slopes, the temperature in the sunny-slope was 1-3 °C higher than that in the shady-slope, and the difference increased as roadbed height increases. However, the culvert serves as a large ventilation duct, exchanging the amount of thermal rotation and weakening the temperature difference between the two sides. Numerical simulation of the temperature fields was carried out for discussing roadbed fill materials and culvert structures. The results indicated that, under the current design conditions, a pipe-style culvert shows a more stable thermal regime in the freezing period, while a box-styled culvert showed a more stable thermal regime in the thawing period. The anti-frost and insulation engineering measures were also discussed, and several critical design parameters were proposed and optimized. At last, it was found that the most suitable configuration was a box culvert with one section transiting to embankments, and this configuration was recommended for construction of high-speed railway in the seasonal frozen regions.