Abstract:Traffic load is one of the main live loads of pipelines buried under the road surfaces. The urban water supply pipelines are subjected to repetitive traffic loads during their operational lifespan, which may potentially lead to the fatigue failure of the pipelines. However, existing research mostly focuses on the static or dynamic mechanical responses of pipelines, with limited studies on the fatigue mechanical performance of pipe joints.This paper considered the statistical data on highway vehicle loads alongside constant loads such as soil pressure and pipe self-weight at first. The mechanical responses of ductile iron pipe joints under traffic loads were calculated using ABAQUS. Subsequently, to simulate cyclic loading under actual traffic conditions, bending fatigue tests of ductile iron pipe joints were conducted under internal water pressurebased on the principle of equivalent rotation angle. The study established the relationship between the maximum rotation angleat pipe joints and leakage rate under various fatigue load amplitudes. Finally, the fatigue life of pipelines under variouscombinations of traffic load was analyzed using the cumulative damage theory and the relationship between the fatigue load amplitude and cycle number of DN200 ductile iron pipe was obtained based on the test data. The research results indicate that: (1) the maximum rotation angle at pipe joint is an important indicator for evaluating the degree of fatigue failure, (2) the maximum rotation angle of pipe joint is positively correlated with the leakage rate, with leakage accelerating as rotation angle increases continuously; (3) the degradation of rubber ring at pipe jointssignificantly contributes to seal failure and subsequent leakage.
