Consolidation behavior and modified model of Qinghai-Tibetan clay subjected to freeze-thaw cycles

Abstract

Freeze-thaw cycles (FTC) cause significant changes in the physical and mechanical properties of soil, leading to structural alterations that can seriously threaten the safety and longevity of engineering structures. To investigate the consolidation characteristics of soils subjected to FTC, 18 sets of consolidation compression tests were carried out with saturated clay. Using a modified consolidation apparatus, the changes in pore-water pressure (PWP) and strain during consolidation were measured, with a focus on the effects of dry density and the number of FTC. The results show that although the overall patterns of PWP and strain during consolidation are similar before and after FTC, variations in dry density and the number of FTC lead to significant differences in the measured values. Specifically, PWP decreases while soil deformation increases with an increasing number of FTC cycles, even across different dry density conditions. The most pronounced changes in PWP and strain occur during the first 1–3 FTC cycles, with some samples showing continued significant changes up to 3–5 cycles. However, beyond five FTC, the increments in PWP and strain become considerably smaller. Meanwhile, an approximate linear relationship was observed between the peak PWP and steady-state strain values during graded loading, with this linearity decreasing as dry density increases. In addition, the Burgers model was modified based on the measured dissipation pattern of PWP to overcome the shortcomings of the traditional Burgers model. The modified Burgers model provides a more accurate representation of the soil's deformation process following FTC compared to the traditional model. This study can provide theoretical guidance for predicting the deformation of soils after freeze-thaw cycles.

Keywords

• Saturated clay
• Freeze-thaw cycles
• Pore-water pressure
• Consolidation deformation
• Burgers model