关键词: 冻土, 振陷模型, 低温动三轴试验, 轴向等幅循环荷载, 中国青藏铁路

Abstract:

Based on dynamic triaxial test at low temperature, deformation behavior of silty clay sampled from Beiluhe section of Qinghai-Tibet Railway under long-term cyclic loading is studied. At different negative temperatures, frequency, confining pressure and water content, relation curves between residual strain and vibration times of frozen soil are investigated; vibration excited subsidence model is built; and its parameters along with influential factors are discussed. The results demonstrate that the parameters are deeply influenced by adopted vibration times, among which, B(viscous, plastic, rheological and creep rate) decreases and C(creep regression coefficient) increases sharply with increasing of vibration times; with the exception of quickly destroyed specimens, both of the two parameters tend to be stable when vibration up to critical times; under the same vibration times, both of the two parameters decrease with rising of temperature, increasing of dynamic stress magnitude or chamber pressure, and are influenced little as vibration frequency higher than 6Hz. The work makes a contribution to properly predicting of settlement induced by residual deformation of frozen soil under long-term dynamic loads and provides experimental data to further research on dynamic characteristics of frozen soil.

Key words: frozen soil, model of vibration excited subsidence, dynamic triaxial test at low temperature, cyclic axial loading with constant magnitude, Qinghai-Tibet Railway