An Experimental Study on the Mechanical Capability of a Rubber Gasket Joint in a Ductile Cast Iron Pipeline under Stretch-Bending

Buried pipelines suffer axial and bending force under earthquakes and ground displacements, and during the process, deformations and damages usually occur at the pipeline’s joints. Based on the pulling-out test and bending test, this paper is aimed at carrying out stretch-bending test on the rubber gasket joint in the ductile cast iron pipeline, which is commonly used in the water supply system. By applying different eccentric tensions (eccentricities are 25, 50, and 180 mm respectively) to the joint of two pipes, the relationship between axial pulling force and displacement, moment, and rotation angles were obtained meanwhile nonlinear mechanical characteristics and failure state of pipe joints were analyzed. Conclusions are drawn as follows: The deformation at joint is coupling response of axial displacement and bending deformation, which shows nonlinear behavior and pronounced variability. The damage state is pull-out of the joint by the tension with small eccentricity mainly due to the tension. The damage state is bell broken by the tension with large eccentricity mostly owing to the bending.