Research on the dynamic softening deformation characteristics and pore-water pressure response of warm frozen soil

Traffic- induced dynamic loads can destabilize frozen soil foundations, leading to various engineering problems. Compared to static loads, dynamic loads cause greater deformation and induce a softening effect that reduces the soil's resistance. This study conducted triaxial compression tests under both dynamic and static loads to compare how different temperatures, stress amplitude, and dry densities affect deformation behavior, internal temperature evolution, and pore-water pressure (PWP) response. Furthermore, orthogonal experimental design was employed to investigate the interaction effects between stress and temperature. The results indicate that axial strain and PWP respond similarly under both dynamic and static loads. During the initial loading stages, PWP increases, with dynamic PWP showing significant dissipation later, while static PWP stabilizes gradually. The trends in dynamic and static axial strain changes are largely consistent, but dynamic axial strain develops 2–3 times faster and causes a significant warming effect within the frozen soil mass. When deformation is minimal, axial strain and PWP are positively correlated. During the PWP increase phase, its rate of change is more closely correlated with the axial strain rate. The interaction between temperature and stress is more pronounced under dynamic loads. The results confirmed that warm frozen soil undergoes pronounced softening under dynamic loading. These findings contribute to advancing the theoretical understanding of frozen soil dynamics and support improved design strategies for transportation infrastructure in cold regions.