Here, a seismic-response analysis model was proposed for evaluating the nonlinear seismic response of a pile-supported bridge pier under frozen and thawed soil conditions. The effect of a seasonally frozen soil layer on the seismic vulnerability of a pile-supported bridge pier was evaluated based on reliability theory. Although the frozen soil layer inhibited the seismic response of the ground surface to a certain extent, it exacerbated the acceleration response at the bridge pier top owing to the low radiation damping effect of the frozen soil layer. Furthermore, the frozen soil layer reduced the lateral displacement of the bridge pier top relative to the ground surface by approximately 80%, thereby preventing damage caused by earthquakes, such as falling girders. Compared to the thawed state of the ground surface, the bending moment of the bridge pier in frozen ground increases. However, the bending moment of the pile foundation in frozen ground decreases, thereby lessening the seismic vulnerability of the bridge pile foundation. The results of this can provide a reference for the seismic response analysis and seismic risk assessment of pile-supported bridges in seasonally frozen regions.

To solve the problem of poor engineering characteristics of silty clay subgrade of Changshuang Expressway area in Jilin Province, this study proposes an economical and efficient approach by utilizing lime as a stabilizer. The effects of lime content and curing conditions on the durability of lime-stabilized silty clay (LSC) were examined through immersion, freeze-thaw, and wet-dry cycle tests. The strength under freeze-thaw and wet-dry cycles initially increased and then decreased with cycle repetition. The final strength of LSC was significantly affected by the lime content, with 7 % being the optimum for subgrade fill in this area. Subsequently, the reliability of the experimental results was validated through ANOVA. Lime stabilizers can significantly reduce the economic cost of silty clay subgrades in practical applications. Through Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD), it was found that both water immersion and freeze-thaw cycles caused damage to the cementitious materials in LSC, whereas wet-dry cycles promoted the growth of cementitious materials. The experimental design of the study considered the frost heave and thaw settlement of high-water-content silty clay in Changshuang Expressway area, with an extreme air temperature of- 39.8 degrees C and a subgrade temperature of-15 degrees C. The findings provide new references for LSC subgrade construction in similar seasonally frozen regions and offer valuable insights for the experimental design of other soil types.