青藏铁路昆仑山隧道回冻预测分析

针对青藏铁路昆仑山隧道围岩多年冻土融化较多的问题，考虑水分迁移和冰水相变耦合影响，根据瞬态温度场问题的热量平衡控制微分方程和质量迁移方程，应用伽辽金法推导出了有限元计算公式并编制了计算软件。运用该计算软件对昆仑山隧道施工期间的融化进行了回冻预测分析。分析结果表明：保温材料对昆仑山隧道的回冻起着阻碍作用。在现场观测寒区隧道围岩的温度和应力时，必须考虑施工期间融化圈的影响，而且观测时间要长一些。否则，测量的温度和应力与隧道稳定后的温度和应力有较大的差异。

Forecast analysis for the re-frozen of Kunlunshan Tunnel on Qing-Tibet railway

According to the thawed range of the permafrost surrounding Kunlunshan Tunnel on Qing-Tibet railway being very large,water transfer and phase change were taken into account and the finite element formulae of this problem and computer program were derived from the governing differential equations and water transfer equations using GALERKIN's method.Using the computer program,forecast analysis for the re-frozen of Kunlunshan Tunnel was made.The analysis results show that insulation will delay the re-frozen of Kunlunshan Tunnel.The thawed range of the permafrost surrounding the tunnel in cold regions caused by construction must be considered,and the time of observation should be prolonged when their temperature and stress are observed in situ,or observation value will largely be different from real value in the state of the tunnel stability.