青藏直流联网工程±500kV输电线路的工程问题分析

青海至西藏±500kV直流联网工程为我国首次在青藏高原多年冻土区全线铺设的高等级输电线路,该工程建设完成将对西藏经济与社会的发展起到重要的保障和支撑作用。由于输电线路将跨越青藏高原多年冻土区,冻土特有的工程问题将对工程设计、施工和安全运营产生重要影响。为保证工程建设的顺利进行项目组就其中的冻土、冻土工程等问题进行了较为系统的研究,并进行沿线的冻土调查和现场的试验研究。研究结果表明：输电线路布设与青藏公路基本相同,其中高含冰量冻土约占多年冻土线路段的59%,低含冰量冻土约占多年冻土线路段的25%;输电线路的主要工程问题为冻胀融沉、冻拔问题,不良冻土现象、气候变暖、冻土退化等问题会对线路工程稳定性产生影响;笔者还就输电线路选线选位原则、冻土勘察方法与原则、冻土区工程施工方法的选择等关键问题开展了系统研究。研究成果将为即将开工的±500kV青藏直流联网工程塔基定点、设计和施工以及线路选择提供科学依据。

Research on Frozen Engineering of Qinghai-Tibet 500kV DC Power Transmission Line

Qinghai-Tibet ±500kV DC Power Transmission Line is a high-grade transmission line which is constructed for the first time in permafrost zone of Qinghai-Tibet Plateau,which will play an important role for the development of Tibet＇s economy and society.Due to spanning permafrost zone of Qinghai-Tibet Plateau,specific engineering problems of frozen soil will have an important influence on engineering design,construction and safe function.In order to complete the engineering construction successfully,the project team has studied the frozen soil and permafrost engineering problems,and at the same time,makes permafrost investigation and spot trial.It is shown that the paths of the transmission line and Qinghai-Tibet Highway are the same,and ice-rich permafrost accounts for more than 59% of the total permafrost zone and ice-poor accounts for 25%.The main engineering problems of the line are frozen heave and thawing settlement,the harmful permafrost phenomena,climate warming,permafrost degradation and so on.Therefore,the unique engineering problems of the line will affect the project of the line.The suggestions about principles of choosing the transmission line,the way and code of frozen-soil investigation and construction way in frozen area are put forward.The study results will provide the useful scientific basis for design and construction of the transmission line.