Abstract
The creep deformation of expansive soil has been considered as a vital threat to the safety in engineering construction because it may cause serious slope diseases in geological engineering. Meanwhile, since expansive soil usually remains in unsaturated state, its mechanical property is significantly affected by the seasonal environment. Therefore, the nonlinear deformation of expansive soil has received increasing attention, especially the humidity-dependent creep properties. This study focused on the stability of the unsaturated expansive soil subgrade considering rainfall and the creep behavior. Pressure plate extractor and direct shear tests were performed to investigate the hydro-mechanical and creep characteristics of the unsaturated expansive soil. Both the Van-Genuchten and Burgers models were applied to analyze the test results and inserted into the numerical model of the slope under rainfall infiltration. Results show that the compaction degree and the stress state was closely related to the water holding capacity of the expansive soil. The nonlinearity of the creep behavior became increasingly obvious with the increase of time and the stress level. The safety factor of the slope decreased as the rainfall time increased, and the most dangerous slide of the slope moved toward the foot of the slope. Considering the long-term creep process, there was a period of rapid growth in horizontal displacement that is detrimental to the stability of the slope. Besides, the rainfall infiltration could accelerate the slope failure before and after this creep process.
Highlights
Disasters caused by expansive soil have received increasing attention with the development of engineering construction (Ikeagwuani and Nwonu, 2019)
The Van-Genuchten model used to fit the soil–water characteristic curve (SWCC) of expansive soil is reported in this study, and the effects of stress and compactness on the SWCC of expansive soil were analyzed
The Burgers model was used to study the creep behavior of expansive soils to evaluate the effect of the stress states on the creep properties
Summary
Disasters caused by expansive soil have received increasing attention with the development of engineering construction (Ikeagwuani and Nwonu, 2019). Under the drying and wetting cycles, the overlying pavement with expansive soil will be prone to uneven settlement, leading to the destruction or instability of the engineering structure (Lu et al, 2019). This phenomenon presents significant challenges to road engineering in designing and building stable. The most expansive soil subgrade structures are located above the groundwater level and remain in unsaturated state for a long time. The current traditional framework used for pavement design and construction ignores the water migration law and its effect on unsaturated embankment soil
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