Test of Long Collar with Superior Ability to Absorb Ground Displacement and Pipeline Design Method of Long Collar to Cross Faults

This study proposes improving a method for designing a water pipeline against fault displacement by incorporating long collar into hazard resilient ductile iron pipe (HRDIP) pipeline. A hazard resilient joint pipeline is capable of absorbing the large ground displacements by movement of its joint (expansion, contraction, and deflection) and the use of the joint locking system. Existing hazard resilient joint pipelines have been exposed to several severe earthquakes such as the 1995 Kobe Earthquake and the 2011 Great East Japan Earthquake, and there has been no documentation of their failure in the last 40 years. These performance records of hazard resilient joints are also highly evaluated in the West Coast of US; therefore hazard resilient joint has been widely adapted as a measure for fault, earthquake, landslide, etc. On the other hand, there are many faults which are estimated with large movements in the West Coast of US. In those locations, additional countermeasures are required when the fault displacement exceeds 1.8 m because this displacement could stress the hazard resilient joint pipeline beyond the elastic limit; therefore special countermeasures are adapted to increase the performance of the pipeline such as using long collar, which has an expansion/contraction performance more than 10 times as much as regular hazard resilient joint pipe joint. In this study, researchers conducted long collar joint deflection tests with fully expanded and contracted situations to make the relation between expansion/contraction and deflection performance clear. Based on the test results, researchers set the long collar’s joint deflection feature considering joint expansion/contraction accurately for finite element modeling (FEM) analysis and optimized the design of hazard resilient joint for fault movement.