Influences of local factors on permafrost occurrence and their implications for Qinghai-Xizang Railway design

The construction of the Qinghai-Xizang Railway is facing some challenges posed by the presence of warm and ice-rich permafrost and predicted climate warming. To resolve these issues and ensure the railway a success, adjustments will have to be made in design strategies and principles. This paper presents several examples of permafrost-distribution anomaly caused by site-specific conditions. It analyzes the mechanism through which these local factors influence the occurrence and preservation of permafrost by modifying the heat convection and conduction patterns, and the amount of solar radiation received by the ground surface. A good understanding of these anomalies in permafrost occurrence is significant as it may provide some hints on the techniques and measures we can use to artificially simulate similar effects. A number of measures can be taken to lower ground temperature and to counter the effect of cli-mate warming. These measures include use of proper roadbed material and configuration, in order to adjust solar radiation, heat convection and conduction patterns. It is recommended that a new proactive approach be adopted in the railway design. This approach emphasizes the use of all the above-mentioned measures to cool down the roadbed. This is different from previous methods of preventing permafrost from thawing by utilizing more thermal resistant materials.