多年冻土区输电线路冻融灾害防控研究

Prevention and control of freezing and thawing disasters in electric transmission lines constructed in permafrost regions

随着我国冻土区输电线路的不断建设,冻土问题日益引起人们的关注,如何正确处理多年冻土与输电线路工程的关系,已成为输电线路建设的关键问题之一.文中主要就多年冻土区输电线路建设所遇到的冻融灾害以及相应对策进行了分析和讨论.相对于公路和铁路,输电线路基础均为埋入式基础,对冻土扰动强烈、传热作用突出.输电线路属于点线工程,在线路选线和设计阶段,通过输电线路选线、塔基类型的合理确定,可在很大程度上避免或减少冻融灾害的产生.在选择塔基类型时应重视冻拔作用对塔基稳定性的影响.输电线路基础为明挖基础时,施工周期和时间的选择、施工过程的控制等对减少热扰动作用明显.随着工程同步进行的冻土基础监测,对输电线路塔基稳定性分析、工程合理转序、运营维护都具有重要意义.输电线路建设中的冻土问题在不同建设阶段,防控重点均有所不同,只有全面把握,才能科学应对.

As China＇s ongoing electric transmission lines constructed in permafrost regions, the issues related to permafrost are concerned increasingly. The general disasters of thawing and freezing in the transmission lines constructed in permafrost regions and the solutions are analyzed in this paper. It is found that since the moment when the tower foundation of transmission line was buried, the permafrost around the foundation has been dis- turbed more strongly and the heat transfer has been more prominent as compared with those in highway and rail- way foundations. Therefore, controlling of diseases resulted from frost heaving and thaw settlement should be conducted in every stages of the construction of transmission lines. Transmission line belongs to dotted line pro- ject, so the frost heaving and thaw settlement would be avoided or eliminated by wise selection of line and tower type. Frost heaving should be paid more attention in choosing tower type. The choice of the construction period and time and the controlling of the construction process will be effective in controlling thermal disturbances if there is an open excavation foundation. A simultaneous permafrost monitoring following the construction going on will play an important role in analyzing project stability, switching engineering construction sequence, and op- erating and maintaining the project. It turns out that the performance of the permafrost issues are varying in dif- ferent stages, it could only be tackled scientifically by a comprehensive research.