Monitoring and Analysis of Fine-Grained Frozen Soil Temperature and Permafrost Table for Transmission Line Foundation

Abstract

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.