昆仑山多年冻土隧道施工温度影响分析

Analyzing the Effect of Tunneling on Temperature of Permafrost in the Kunlun Mountains, Tibetan Plateau

青藏铁路昆仑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它人为活动,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,在ANSYS计算软件的工作平台上开发了计算软件.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,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,必须考虑施工期间的融化圈的影响,而观测时间要长一些,否则,测量的温度和应力与隧道稳定后的温度和应力将有较大的差异.

From in-situ measurement of air temperature and ground temperature inside the Kunlunshan Tunnel in the Qinghai-Tibet Railway, it is found that the thawed range of the permafrost surrounding the tunnel is very large, due to the hydration heat of the concrete lining, insulation measures during winter and other artificial activities. In this paper, taking water transfer and phase change into account, the finite element formulae of this problem and computer program on the base of ANSYS Software are derived from the governing differential equations and water transfer equations using Galerkin's method. Using the computer program, forecast analysis for the re-freezing of the Kunlunshan Tunnel is made. The analysis shows that insulation will delay the re-freezing. The thawed range of the permafrost surrounding the tunnel in cold regions caused by tunneling must be considered. The observation duration should be prolonged, because much time is needed for the tunnel going to be stable.