中文摘要：

青藏交直流联网工程是继青藏公路、青藏铁路等之后,在青藏高原多年冻土区建设的另一种新结构的冻土工程.系统地分析了青藏直流线冻土工程与其它工程的差异,并就该工程冻土基础温度、水分、应力和应变监测系统的建立和观测要素,以及初步观测结果等问题进行了讨论.通过对2011年全年观测数据分析发现,整个监测系统可以准确、及时反映输电线路冻土基础的不同性状和特征,可以反映影响塔基稳定性的主要因素及其变化趋势.初步观测结果表明,在不同时段,监测塔式基础底部总体处于冻结状态、塔基基本稳定,但个别监测塔基地温增温幅度、上限融化深度较大,沉降变形呈现增加趋势.鉴于工程完工和荷载作用的时效性,塔基稳定性应处于动态变化过程之中.为正确评价塔基稳定性,需要对塔基回填土的冻融、水热变化和塔基变形等重要过程进行长期监测研究.

英文摘要：

Following the Qinghai-Tibet Highway and Qinghai-Tibet Railway,the Qinghai-Tibet DC Transmission Line Interconnection Project is major permafrost engineering,and it is also a new type of engineering structure in permafrost regions.In this paper,the differences between the Qinghai-Tibet DC Transmission Interconnection Project and other permafrost engineering were analyzed.Then,the establishment of the monitoring system around the tower foundation,the observation elements and preliminary observational results were discussed.Analyzing the observation in 2011 found that the monitoring system is able to recognize accurately the various characteristics of the tower foundations in permafrost regions,as well as the main factors that control the stability and the variation tendency of tower foundations.The preliminary results revealed that the base of the monitoring tower foundations froze within the year,the tower foundation was stationary overall.However,near several tower foundations the ground temperature and the depth of the permafrost table were increasing,and the settlement and deformation showed a rising trend.In view of the project having completed just about 1 year,the stability of the tower foundation under change yet,it is necessary to monitor the load effecting on the tower foundation more time.Further more,the freezing-thawing and hydrothermal processes of the backfill,together with the deformation of the tower foundation,needs to analyze and research combining with the monitoring data and the simulation calculation.