To analyze refreezing state and permafrost table of the frozen ground for the Qinghai-Tibet DC Transmission Line Engineering, temperature monitoring tests of fine-grained frozen soil were carried out and the thawing depth of backfilled soil was measured in Wudaoliang region of the Tibetan Plateau. The ground temperature fluctuates over time, and the fluctuation characteristics are determined by soil properties, climate, depth and other factors. The seasonally thawed layer is in the shallow of undisturbed frozen ground and backfilled soil. The maximum thawing depth of backfilled soil was about 2.3m more than permafrost table of the undisturbed frozen ground. Soil near the foundation slab was keeping frozen state. The results show that the construction of frozen ground in cold season is helpful to refreeze and keep frozen state of the ground, and can provide a basis for stability analysis of the engineering foundation.

Through the vertical static load test of pile, studied and demonstrated the applicability of cast-in-place piles in the construction of a thermal power plant’s in Guangxi Zhuang Autonomous Region, china. By testing the internal force of pile shaft, obtained the distribution of axial force, side friction and tip resistance, and ascertained the vertical bearing capacity of punched cast-in-place piles in the engineering geological conditions of this project. This research provides the important quality control standards and design basis for the follow-up pile foundation construction of large area of this project, and also provides reference for other projects in this area.

Transmission lines pass through various types of regions in China and some of that are corrosive. The foundation concrete of transmission lines in corrosive environments had shown serious deterioration, which usually caused by concrete deterioration, rebar corrosion, degradation of bond strength between rebar and concrete due to various corrosive effects. There are salt lake areas in west China where some power transmission channels pass through. Field tests are carried out in Golmud area to research the durability of foundation concrete of transmission lines. And test results show that the concrete strength in the air is higher than underground and the carbonation depth of the foundation concrete decreases with the increase of concrete compressive strength.