Analysis of Three-Dimensional Temperature Characteristics of Dry Bridges on Qinghai-Tibet Railway in Unstable Frozen Soil Region

Based on the differential equations for heat balance control of transient temperature field with phase changes, the finite element formulae are developed. Under condition that the climatic warming is considered, the three-dimensional numerical analysis is made for the temperature characteristics of the dry bridges on the Qinghai-Tibet Railway in the unstable frozen soil region, using the finite element formulae mentioned above. The analysis results show that in the coming 20 years, the operation of the dry bridges built in the frozen soil region could provide much of cool energy for the permafrost around the bridge piles, well protect the permafrost, and consequently could ensure the safety operation of the Railway. In addition, the analysis also proves that it is feasible to build the types of the dry bridges on the Qinghai-Tibet Railway that is currently under construction in the high-temperature frozen soil region.