Jointed Pipeline Response to Large Ground Deformation

Abstract

The performance of segmental pipelines under large ground deformation is strongly influenced by the axial pullout and compressive load capacity of their joints, as well as by the limits on joint rotation during permanent and transient ground deformation. Although ductile iron (DI) pipelines with push-on joints are commonly used in water distribution systems, experimental data and numerical simulation related to their performance under large ground movements are lacking. This paper reports on a series of specially designed four-point bending experiments and finite-element (FE) simulations to characterize 150-mm (6-in.) diameter DI push-on joints. The results were used to develop a relationship between rotation and metal binding as a function of axial pullout, as well as to determine the magnitudes of rotation and moment that initiate joint leakage. FE simulations were performed to investigate the deformation associated with joint leakage. Uniaxial tension and one-dimensional compression tests were performed on the elastomeric gasket and fitted with hyperelastic strain energy approximations to characterize behavior under extreme loading. Numerical models demonstrate joint leakage to be independent of load path, and that a unique pressure boundary predicts leakage for many combinations of deformation.