Thermomechanical Response of Buried Pipelines to Cold Wave-Induced Nonuniform Temperature Gradients

Nonuniform temperature fields induced by cold waves can alter the stress state of buried pipelines. However, current research on the thermomechanical effects of cold waves on buried pipelines remains insufficient. This study takes an operational DN1200 buried water transmission pipeline in Shanghai during cold wave periods as the research object and systematically explores the temperature evolution characteristics and stress distribution laws of buried pipelines under the action of cold waves through a combination of on-site monitoring, finite-element (FE) simulation, and theoretical derivation. On-site monitoring results show that the temperature response of each part of the pipeline lags behind the air temperature change: the lag time is 24–67 h for the pipe crown; 82–142 h for the pipe invert; and 11–32 h for the water. Cold waves significantly amplify the temperature difference between the pipe crown and invert as well as the temperature difference between the inside and outside of the pipeline. The established soil–pipe finite element model indicates that the stress of the pipeline under cold wave action is dominated by hoop stress, with the maximum value occurring at the pipe invert; further, the variation of hoop stress lags behind the air temperature change due to the heat transfer delay of the soil. After linear correction, the theoretical formula for the hoop stress of the pipeline under nonuniform temperature is consistent with the finite element simulation results ( R 2 = 0.9493 ), and the average error is controlled within 2%. This study can provide theoretical support and practical guidance for the cold-resistant design, safety assessment, and disaster prevention and mitigation of buried pipeline networks.