青藏高原多年冻土区铁路路桥过渡段温度场三维数值分析

 基于过渡段相变三维传热分析模型，对未来30 年路桥过渡段温度场进行分析与预测，研究了过渡段阴阳坡时空效应对路桥过渡段长期热稳定性的影响。计算结果表明：随着路桥过渡段运营时间的增长，各纵断面最大融化深度部位逐渐由过渡段转移到台背后路基，各横断面最大融深及最大融化速率位置均由阳坡坡脚转移到路基中心与阳坡路肩之间，相同运营时间，沿台背方向阴坡坡脚冻土上限变化并不明显；随着运营时间的增长，各横断面阳坡坡脚融化速率均大于天然冻土地基融化速率；各横断面除阳坡坡脚的其余部位在运营25 年以前，人为上限退化率基本小于天然冻土上限，运营25 年后，人为上限退化率逐渐大于天然冻土上限。

Numerical Simulation of Thermal Field in Permafrost Embankmentbridge Transition Section of Qinghai-tibet Railway Bridge

A 3-D numerical simulation model of the permafrost roadbed-bridge transition section thermal field is built and the finite element method is adopted to predict and compare the thermal field for different transition section heights and different types of permafrost by raising temperature by 2.6℃ in the coming 50 years. The calculated results show that with the time, the maximum thawing depth profile parts move gradually from the transition section to the place behind the embankment,and the positions of the largest cross-sectional thawing depth and the maximum thawing rate move from the northern slope foot between the slope shoulders to the subgrade center. The cross sectional northern slope foot thawing rate becomes greater than the natural thawing permafrost foundation rate. For the rest parts of the transect before the operational 25 years, the artificial permafrost table degradation rate is lower than the natural permafrost table, and 25 years later, the artificial permafrost table degradation rate is higher than that of the natural permafrost table gradually.