An experimental study of the impact of liquefaction-induced displacement on buried pipelines for buildings

This study aimed to investigate the impact of soil liquefaction-induced displacement on buried pipelines critical to the serviceability of buildings, including those for potable water and natural gas. The emphasis was on the service lines connecting distribution mains and buildings due to their higher vulnerability. Two types of forced displacement tests were conducted on full-scale physical models of buried service lines. One simulated the uplift or subsidence of distribution mains as the soil surrounding the pipelines is completely liquefied, while the other simulated the building settlement due to partial loss of foundation bearing capacity in various conditions of surrounding soil. The longitudinal strains, deflection, and possible leakage of pipelines were monitored during these tests. The results showed that sufficiently large displacement could cause yielding and pulling out from the joint of the pipe. However, high pipe flexibility and joint strength provided adequate resilience of buried pipelines to these damage modes. The corrugated section of stainless-steel pipe was also verified to reduce strain in the pipeline. Additionally, when a pipeline was subjected to building settlement, liquefaction of surrounding soil or not led to different strain distribution and deflection along the pipeline. Local buckling of the pipe near the loaded end was induced in non-liquefied cases due to the combination of forced displacement and soil reaction. These findings give a better knowledge of the resistance performance of buried pipelines against liquefaction-induced displacement.