Thermal stabilization of duct-ventilated railway embankments in permafrost regions using ripped-rock revetment

- Remedying effect to the temperature field of high and low-positioned duct-ventilated embankment is investigated.
- Thermal character and sunny and shady effect of different conducted duct-ventilated embankments are analyzed.
- Variation of the temperature decreasing range after the remedy is presented.
- A further movement of the artificial permafrost table is found after the remedy.

Duct-ventilated railway embankment (DVE) is relatively effective at preserving underlying permafrost under the current climatic conditions. To increase its capacity to adapt to climate warming, a ripped-rock revetment was added to the DVE. To evaluate the effectiveness in cooling of different embankment treatments, long-term in-situ soil temperature data were collected from eight experimental embankment sections along the Qinghai-Xizang Railway in the Beiluhe region between 2002 and 2012. Analysis of these soil temperatures shows that the addition of the ripped-rock revetment is effective in improving the cooling capacity of the DVE, enhancing the thermal stability of both the embankment body and the underlying permafrost. Soil temperature in the overall embankment decreases about 0.5-1.0 °C, the temperature of the underlying permafrost decrease, the artificial permafrost table is further raised, and average range for cooling effect gets further enlarged under the joint effect of ventilated ducts and ripped-rock revetment. What is more, this cooling effect of embankments with low-positioned ducts is greater than that with high-positioned ducts. Besides, cooling effect is greater for ducts with a diameter of 30 cm coupled with ripped-rock revetment than that of 40 cm. Another positive outcome of this reinforcement is the greater restriction in the temperature difference between the sunny and shady embankment shoulders, especially for the embankments with low-positioned ducts or with a diameter of 30 cm. Therefore, implementation of ripped-rock revetment is recommended for duct-ventilated embankments, particularly for embankments where high-positioned ducts are present.