冻土区输电线路塔基选位的影响因素分析

THE INFLUENCE FACTOR ANALYSIS FOR SITE SELECT OF TRANSMISSION LINE IN FROZEN EARTH AREA

青海—西藏±500kV直流联网输电线路工程跨越整个青藏高原,其生存环境不可避免与冻土有着紧密联系,冻土特有的冻胀、融沉特性给线路的勘测、设计、施工及后期运营带来了极大挑战。本文对取自青藏高原的原状和重塑冻土样样品进行了物理力学试验。结果表明:同种土在不同含冰量下,随含冰量的增大,则冻融特性敏感性增强;不同性质的土,在含冰量相同的情况下,颗粒越细,则冻融特性越敏感。同时,分析认为:塔基地质环境、不良冻土现象、不同地貌单元、冻土的热稳定性特征及施工作业便捷性等都是影响塔基稳定性的重要因素。

The ±500kV Direct Transmission Line is across the entire Qinghai -Tibet plateau. So its environment has a tight link with frozen soils. Because of freezing soil specialty of frost - heaving and thaw - settlement, the transmission line would meet the great challenge in survey, design, construction and operation in post - construction stage. Therefore, in order to learn more about permafrost engineering problems of transmission line, the physical and mechanical tests are conducted. This paper analyzes the influence factors on the tower stability. The test results show that freezing and thawing behavior can increase the sensitivity as the water content increases for the same soil samples. If the water content keeps the same, the freezing and thawing behavior increases the sensitivity as the particle size decreases for different soil samples. Also, the results show that the geological environment, harmful features of frozen ground, different geomorphic units, thermal stability characteristics of permafrost, and the convenient construction are the factors influencing the tower foundation stability.