Analytical Modeling of Buried Pipeline Response to Permanent Earthquake Displacements

摘要

The performance of continuous and jointed buried pipelines subjected to permanent differential ground movements caused by earthquakes, is examined. Observations of damage along the Sylmar segment of the San Fernando fault zone show that pipelines with rubber gasket joints perform substantially better than those with cement-caulked joints, and that lines of Mannesman steel are more heavily damaged than lines composed of cast iron or other types of steel. Behavior of various types of pipeline coupling was studied and an assessment made of their vulnerability to differential ground movement. Results of finite element modeling of jointed pipeline response to strike-slip faulting are summarized. The most important parameters affecting pipeline response to strike-slip faulting is the angle of pipeline/fault intersection. Pipeline performance is represented as a plot of the total fault offset to cause failure versus the angle of pipeline/fault intersection. For pipelines with flexible, gasketed couplings, this relationship is derived from two distinct curves: one determined by bending failure of the pipe and the other by axial pull-out at a coupling. Optimum orientation of the pipeline relative to the fault occurs at the transition point between failure by bending and coupling pull-out. The long-term records of maintenance for buried pipelines in areas of fault creep are examined.