This study presents experimental results from scale model tests on laterally loaded bridge pile foundations in soils subjected to seasonal freezing. A refined finite-element model (FEM) was established and calibrated based on data obtained from the experiments. Furthermore, the model was utilized to investigate the impact of soil scouring depth on the lateral behavior of bridge pile foundations embedded in seasonally frozen soils. The findings indicate that soil freezing significantly enhances the lateral bearing capacity of the pile-soil interaction (PSI) system while reducing lateral deflection of the pile foundation. However, soil freezing results in increased damage to the pile foundation and upward movement of the plastic zone toward the ground surface. Under unfrozen conditions, significant plastic deformations occur on the ground surface and even inside the piles due to the extrusion effect. Additionally, increasing soil scouring depth significantly reduces the lateral bearing capacity of the PSI system while also increasing lateral deflection of the pile foundation for a given load level. Notably, when the scouring depth exceeds 2 m in unfrozen soils, the entire pile experiences obvious deformation and inclination, exhibiting a short-pile behavior that negatively affects the lateral stability of the pile under lateral loads.

Chiaia station is one of the art stations of Line 6 of the Naples underground network; it was constructed in a 50-m-deep excavation, a few meters from historic buildings and 4.5 m from the main facade of a sixteenth-century Basilica. The excavation, carried out partially in loose to medium dense sands overlying the soft rock formation of Neapolitan Yellow Tuff (NYT), was supported by a retaining wall made of contiguous bored piles braced with internal struts and prestressed ground anchors. The excavation sequence was quite complex due to archeological findings and to the presence of anthropic cavities used over the centuries to quarry NYT blocks. One of the key goals of the design was to limit movements around the shaft to prevent damage in the historical buildings. Long-term monitoring data obtained during nearly 9 years confirm the success of the overall construction process. A rather complex three-dimensional (3D) finite-element model with constitutive relationships for both the upper sandy layers and the soft rock is presented in the paper; this model was adopted to back-analyze the data from the monitoring and explore the influence of some of the key features of the case study. The role of the building bending and shear stiffness, of the soft rock stiffness, and of further apparently minor issues-such as the seepage and the ground anchors' prestress-were investigated and discussed with the support of the model calculations. Observed settlements at the end of the excavation were in the range 10-15 mm, and in the long term they increased by 20%-50% to as much as 20 mm. The deflection ratios were very small, in the range 0.05 parts per thousand-0.15 parts per thousand, and no visible damages to the buildings were recorded. These values were reproduced by the finite-element model only after the introduction of the relevant building stiffness.