Abstract:
The increasing trend toward warmer and wetter climatic conditions on the Tibetan Plateau has heightened the risk of rainfall-induced landslides in areas where red clay is widely distributed. This study aims to investigate the evolution of shrinkage characteristics of red clay from the Nangqian area of the Qinghai-Tibet Plateau under repeated freeze–thaw cycles through the direct measurement method. The results show that the freeze-thaw cycle causes the initial structure of the soil to be destroyed and reorganized, resulting in volume shrinkage. After four freeze–thaw cycles, the volume of the sample shows a recoverable expansion and contraction change. With increasing freeze–thaw cycles (
N), the shrinkage characteristic curves of the two initial dry density specimens gradually shift upward, the slope of the proportional shrinkage section significantly decreases, and the curves tend to coincide at
N=5 and
N=7. Meanwhile, the fitting parameters
a and
b of the Fredlund model have smaller numerical fluctuations when
N=7, indicating that the influence of freeze–thaw cycles on soil shrinkage tends to be stable after approximately seven cycles. The freeze-thaw cycle causes structural shrinkage segments in the two initial dry density specimens, and the structural limits are approximately 0.77 and 0.68, respectively. This study provides a theoretical basis for the prevention of freeze-thaw disasters in plateau areas.