Stress Intensity Factor of Double Cracks on Seabed-Spanning Pipeline Surface under the Spring Boundary

In order to study the interaction of multiple cracks on the submarine spanning pipelines under a complex marine environment, the stress intensity factor (SIF) of double circumferential cracks on the surface of submarine pipelines was studied. The model of double cracks was established in the finite element software, and the SIF of double cracks was calculated by using the contour integration method. The SIF of double cracks with different boundaries was investigated. The influence of the distance of double cracks, crack depth ratio, and crack aspect ratio on the SIF of double cracks under the spring boundary were analyzed. The results showed that the change rule of double cracks was the same when the double cracks were the same size under different boundary conditions, and the spring boundary can better simulate the pipeline-soil interaction than the simple boundary. The distance of double cracks under the spring boundary had a greater influence on the SIF of double cracks. The variation of the crack depth ratio and crack aspect ratio had an effect on the change of the SIF of double cracks; increasing the crack depth ratio caused a decrease in the SIF of the main crack, while increasing the crack aspect ratio caused an increase in the SIF of the main crack. The results can provide the reference for the failure analysis of the submarine spanning pipeline.