冻融循环下初始含水率对非饱和膨胀土剪切特性试验

In freezing-thawing cycles, soil moisture changes dramatically, which leads to the change of bearing capacity of expansive soil. In this study, the unconsolidated and undrained triaxial shear tests were carried out on unsaturated expansive soil with different initial water content, and the strength variation mechanism of expansive soil in freezing-thawing cycles was analyzed on the basis of experiments. The influence of initial water content on the deviatoric stress-strain relationship and shear characteristics of expansive soil under freeze-thaw cycle was discussed. The results showed that: 1) The form of deviatoric stress-strain curve of the unsaturated expansive soil changed gradually from strain softening to strain hardening with the increase of water content, while the peak deviatoric stress decreased with the increase of water content; 2) The shear strength of the unsaturated expansive soil decreased linearly with the increase of initial water content; 3) After the first freezing-thawing cycle, the deviator stress and shear strength of the unsaturated expansive soil decreased significantly, and reached stability after 3 to 7 freezing-thawing cycles. This study provides a powerful basis for the engineering design of expansive soil in a seasonal frozen zone.