Verification of the Applicable Range of Large Diameters in the Design Formula of Buried Pipelines Undergoing Fault Displacement

Numerous pipeline-fault crossing studies related to design methods on fault crossings such as fault displacement prediction, impact range setting, and development of countermeasure construction methods were reported recently. It is easy to take proactive countermeasures because the fault map, assumed fault displacement, and tolerance angle between the fault and the pipeline are known. However, the “Seismic Design Guidelines for Buried Pipes” in Japan mentioned the need of countermeasures for fault-crossing buried pipes, but specific design methods and countermeasures were not yet defined. The Japan Society of Civil Engineers Subcommittee has proposed a design formula for calculating the strain generated in buried pipelines (integrated pipelines) subject to fault displacement, and pipeline integrity can be easily judged. However, in this formula, the pipeline is modeled as a beam element, and there is concern about the effect of deformation in the cross-section of large diameter, thin walled pipelines such as water transport pipes. Herein, we report on the application of the design formula to a large diameter pipes which were verified using FEM analysis.