Detection and Assessment of Natural Gas Pipeline Slip

A natural gas pipeline foundation pit collapsed due to the nearby construction somewhere in Guangdong, and the underground silt layer flow leads to the pipe slip deformation. The slip length was 65 m; significant deformation length was 35 m, and 0.7 m on the horizontal deformation. After the deformed part unloaded and stress relieving, the deformation measurement, nondestructive examination of welds, stress calculation, finite element analysis, and safety assessment were conducted. The calculating results showed that the maximum axial stress caused by slip was larger than the allowed stress of pipe at the fourth level area. It was suggested that the rebound pipe continues its service after external stress release, and the pile foundation should be fixed on two sides to improve the safety allowance.