Summary This paper describes an investigation of pipe–soil interaction equations suggested by currently used pipeline seismic design codes and the applicability of these equations to segmented pipelines. The results of computer‐aided analyses were compared to results obtained in full‐scale experiments on a segmented ductile iron pipeline 93 mm in diameter and 15 m in length. The pipeline was installed 600 mm below the ground surface in a sandy soil compacted to two different subgrade reaction values. The type of fault considered was a reverse fault with an intersection angle of 60° with the pipeline, and the fault movement was a total of 350 mm in three same steps in the fault trace direction. The findings of this study demonstrate the necessity of considering the nature of soil behavior in pipe–soil interaction equations and the effects of connection joints on the integrated response of pipelines to fault‐induced ground deformations. A new combination of equations constituting a direction‐wise selection from among the equations proposed by currently used guidelines is introduced as a new series to describe pipe–soil interaction for segmented pipelines and is verified using the results of full‐scale experiments. Copyright © 2014 John Wiley & Sons, Ltd.

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This study proposes “water pipeline system and design method with Earthquake Resistant Ductile Iron Pipe (ERDIP) against fault displacement”. ERDIP pipeline can absorb the large ground displacement at the event of big earthquakes by the joint movement (expansion, contraction and deflection) and the joint locking system. Though the ERDIP pipeline has many experiences of big earthquakes such as the 1995 Kobe Earthquake, the 2011 Great East Japan Earthquake, no documented failure has been reported for 40 years. In case of fault crossing pipeline, there is a possibility for relative displacement of several meters between the pipeline and ground, locally, to occur. This study examined the ERDIP pipeline design to withstand strike-slip fault by FEM analysis with shell element of 1500 mm ERDIP and spring elements which are modeling soil and ERDIP joint. ERDIP pipeline can accommodate about 2m fault displacement by the joint expansion/contraction and deflection, and keep the stress in the pipeline within elastic limit. The additional countermeasure should be required when the fault displacement is over 2m because the pipeline could be stressed beyond the elastic limit. As a countermeasure of over 2m displacement, it is effective to use “Large displacement absorption unit”, which can expand/contract 10 times compare to ERDIP joint and absorb the locally-concentrated axial displacement of pipeline. We confirmed that ERDIP pipeline with “Large displacement absorption unit”, which is named “Large displacement absorption system”, can accommodate more than 3m fault displacement within elastic range stress of the pipeline. We established the optimized layout of “Large displacement absorption unit”. We also established the design method using several “Large displacement absorption unit” when we can’t identify exact fault location, but the fault lies within the range of pipeline location.

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