温度场控制在多年冻土隧道施工中的作用

Effect of temperature control on tunnel construction in permafrost

多年冻土隧道工程首先遇到的问题是如何解决开挖与衬砌的矛盾,因为开挖作业与衬砌施工所需的温度场不同,隧道开挖需要较低的温度场以利于无支护毛洞的稳定,而衬砌施工需要较高的温度场以利于混凝土强度的增长。通过数值模拟分析,提出多年冻土隧道施工温度场的控制参数,并将多年冻土隧道的开挖施工划分为4个阶段:安全施工阶段、相对安全阶段、安全预警阶段和安全隐患阶段。根据这4个阶段的特征,提出各个阶段应采取的相应工程措施,尽可能降低施工风险。通过全方位监测隧道洞内温度场的变化,指导开挖和衬砌的施工。

The first problem of tunneling in permafrost area is how to excavate and how to lining at the same time, because the needed temperature for construction of liner is different from that of excavation. Excavating needs lower temperature for stability of wall rock, while construction of lining needs higher temperature for concrete strengthening. By finite element analysis of temperatures inside tunnel, four phases （safe phase, relatively safe phase, safety precaution phase and potential safety troubles phase） suitable for construction are put forward to guide excavation and construction of lining.