Prediction of compressive creep behaviors of expansive soil exposed to freeze-thaw cycle using a disturbed state concept-based model

Expansive soils are discovered along the high-speed railways in typical cold regions of northeastern China. The long-term safety of slopes with expansive soil along the high-speed railways requires a detailed characterization of the time-dependent performances of expansive soils. In this study, X-ray diffraction, thermal analyses, and triaxial compressive creep tests are performed to explore the effect of freeze-thaw (F-T) cycle and montmorillonite (MMT) content on the creep characteristics of expansive soils collected along the high-speed railways near the stations of Binxi, Jiamusi, and Yanji. The results reveal that an accelerating creep stage in the creep process is observed for soil samples with higher MMT contents. For the expansive soils with higher MMT contents, the creep strain rates in the last creep stage show that there exists a threshold for creep-induced sample failure. The F-T cycle considerably affects the creep deformation of expansive soil and results in a creep failure of expansive soils. An accelerated creep stage is more likely to occur under the action of lower confining pressure. Additionally, by utilizing field investigation and microstructure analysis, the creep failure mechanism of the expansive soil slope after F-T cycle is preliminarily discussed. Finally, a suitable creep model for expansive soils subjected to F-T cycles is proposed based on the disturbed state concept to predict the primary and steady creep stages. The experimental results exhibit good agreement with the predicted values, confirming the validity of the proposed model. This work can provide reliable experimental data for the creep theory of expansive soil subjected to the F-T cycle.