关键词: 青藏红黏土, 冻融循环, 物理性质, 球形模板压入仪, 等效黏聚力

Abstract: Red clay was taken as research object, specimens from which had gone through different numbers of freezing-thawing cycles within a closed system. The changes of particle size composition and physical-mechanical properties of red clay under different freezing-thawing cycles were studied. The results showed that the specimens of powder group and clay group were significantly affected by the number of freezing-thawing cycles. The specimens with red clay particle size of less than 0.001 mm and particle size in the range of 0.01-0.05 mm had enriched in the first 10 cycles. After 10 cycles of freezing-thawing, the content of soil particles with particle size range from 0.002 mm to 0.005 mm had increased obviously with the increase of the cycles, and the content of soil particles with particle size range from 0.01 mm to 0.05 mm had decreased obviously. Soil particle content in the other particle size range had not affected by the number of the cycles nearly. The liquid and plastic limits of the red clay had increased with the increase of the number of the cycles. The effect of freezing-thawing cycles on the equivalent cohesive strength of red clay was more obvious. The effect of freezing-thawing cycles on the equivalent cohesive strength of red clay had varied greatly within the first 10 cycles. The new roadbed with red clay should consider the effect of additional settlement caused by freezing-thawing cycles. It is suggested that the long-term equivalent cohesive strength of red clay should predict by equation of Vyalov or Wu.

Key words: Qinghai-Tibet red clay, freezing-thawing cycles, physical properties, spherical template indenter, equivalent cohesion