【摘要】 青藏铁路风火山隧道现场实测气温和地温资料表明,施工期间隧道衬砌现浇混凝土水化热、冬季施工采取的保温措施以及其他人为活动,造成了该隧道围岩的多年冻土融化较多。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。运用该计算软件对风火山隧道施工期间冻土融化进行了回冻预测分析,分析表明,如果在不铺设保温材料的情况下,隧道的拱顶、左墙以及右墙 3 a 后基本上回冻,而仰拱底到了第 5 a 的 9月 30 日才回冻;如果在铺设了导热系数为 0.03 W/m·K 的保温材料情况下,拱顶 3 a 基本上回冻,左、右墙以及仰拱底到了第 5 a 的 9 月30 日才回冻,所以,保温材料对隧道围岩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,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。更多还原

【Abstract】 According to the in-situ measured data of the air temperatures and ground temperatures inside at Fenghuoshan Tunnel on Qinghai—Tibet railway,the thawed range of the permafrost surrounding the tunnel is extensive,which is caused by the hydration heat of the cast-in-place concrete lining,insulation measurement in the inlet,exit of the tunnel during winter construction,and other human activities. Taking water transfer and phase change into account,the finite element formulae of this problem and computation program are derived from the governing differential equations and water transfer equations by Galerkin’s method. With the computer program, forecast and analysis on the refreezing of permafrost for Fenghuohan Tunnel is performed. The analytical results show that the vault,left wall,and right wall of Fenghuoshan Tunnel will be refrozen in three years,and the arch bottom will be refrozen in September 30 of the fifth years without insulation. On the other hand,if the tunnel is fitted with insulation with thermal conductivity of 0.03 W/m·K,the vault of Fenghuoshan Tunnel will be refrozen in three years,left wall,right wall and the arch bottom will be refrozen at September 30 of the fifth years. Therefore,insulation material will delay the refrozen of permafrost of Fenghuoshan Tunnel. The thawed range of the permafrost surrounding the tunnel in cold regions caused by construction should be considered,and the time of observation should prolong when their temperatures and stresses are observed in site,otherwise observations will differ largely from the real values in the stable state of the tunnel.更多还原