Uniform support from the surrounding soil is important for maintaining the stable operation of buried pipelines. For segmented prestressed concrete cylinder pipe (PCCP), localized soil voids around the joint due to leakage or engineering activities make the pipe unsupported partially and threaten its integrity and strength. In this paper, the impact of a localized soil void on a pipe joint is qualitatively assessed using a beam-on-elastic-spring approximation model. It further provides quantitative analysis through a nonlinear finite element (FE) model of PCCPs and the surrounding soil. The derived algebraic solutions indicate that a unilateral local void induces shear force and rotation at the joint, whereas shear force becomes negligible when the void spans the joint, leading to increased rotation. Moreover, the rotation angle shows a positive correlation with soil load and a negative correlation with pipe diameter. Numerical analysis reveals that void elongation along the pipe length has a more pronounced effect on structural response than void depth and angle. When the void length reaches 2.5 m, the maximum principal stress on the mortar layer of the PCCP increases approximately eight-fold compared to the scenario without voids. Due to the rigidity and safety factor of the PCCP, small voids in the bedding typically do not cause immediate pipe damage or joint leakage; however, they can significantly alter the stress distribution within both the pipe and surrounding soil. As the void develops, the soil may collapse and compromise support, leading to additional secondary disaster risks and potential threats to pipeline safety. This research emphasizes the importance of effective pipe-soil interactions and provides theoretical insights for developing repair strategies for PCCP.

In recent years, the escalating frequency and intensity of extreme weather events like cold waves have heightened concerns regarding their impact on buried water pipelines, posing notable challenges to urban safety. These pipelines are particularly vulnerable to damage from the extreme low temperatures induced by cold waves, which can lead to significant system failures. This paper investigates the mechanical response of buried water pipelines to traffic loading before and after a cold wave using the Finite Element Method (FEM). Initially, a 3D numerical model was created to simulate the temperature distribution in the soil and buried pipe, utilizing field monitoring data gathered during a cold wave event at Shanghai city of Eastern China. Subsequently, a mechanical analysis of the soil-pipe model was conducted, employing the validated soil and pipe temperature field as predefined fields. The effects of temperature change rate, traffic load type, load position, and burial depth on the pipeline behavior are discussed in detail. The results demonstrated that cold waves significantly impact pipeline stress, an effect that is intensified by increased traffic loads. The peak Mises stress increased by up to 21 % for the 1.0 MPa load, underscoring the role of cold waves in amplifying pipeline stress. Moreover, while cold waves increase pipeline stress and vertical displacement, accelerating the rate of temperature change induced by the cold wave reduces the stress. Traffic load exerts the most significant impact at the bell and spigot joints, with effects remaining consistent regardless of joint position. Shallow-buried pipelines experience more pronounced stress changes in the presence of cold waves and traffic load, with stress increasing by 66.8 % at a depth of 1.5 m. This study demonstrates that the bell and spigot joints of shallow-buried pipes are highly susceptible to cold wave effects, especially under traffic loading, necessitating special attention to this potential failure location during such conditions.