Flexible pipes could be used in hazardous environments for their mechanical advantage, consisting of several different layers, each capable of resisting different types of loads. The long slender flexible pipes can be self buried or intentionally buried in the seabed and be exposed to large ground movement induced by ice-gouging, landslides, and fault crossing. In these circumstances, it is of great importance to investigate the flexible pipe deformation and the induced stress around the pipe. Whereas pipeline-soil interaction models in the literature mainly consider a rigid pipeline section, in this paper, works considers a deformable pipeline section were conducted by developing an advanced decoupled numerical framework, simulating a rough bore flexible pipe. Taking advantage of Coupled Eulerian-Lagrangian (CEL) method in computing large deformation problem and finite element models in analyzing deformation and stress responses of multi-layer flexible pipe, the methodology proposed in this paper is capable of estimating cross sectional deformation and local stresses, which may cause failure and significantly increase the risk of collapse.
The flexible pipes are widely used in the offshore conveying water, oil, and gas. They might be self buried in the ocean floor or trenches and backfilled for physical protection. Those pipelines, even when buried, are inserted in harsh environments and are constantly at risk of exposure to large ground deformations caused by fault crossing, landslide zones, ice gouging in arctic areas and other natural phenomena. This raises the concern of pipeline safety since failures may occur in pipelines under bending conditions, which may cause excessive tension and compression. When compared to rigid pipes, flexible pipes have low bending stiffness and could significantly deform and derive strength from the surrounding remolded soil and adjacent undisturbed soil. Therefore, it is of great importance to highlight the performance verification of buried flexible pipelines exposed to large soil deformation among the top design priorities.
The soil-pipeline interaction problem is a well-known challenge for research groups in both industry and academia. Theoretical and experimental models are available to predict the ultimate lateral resistance or force-displacement responses of embedded moving structures (e.g., ALA 2001; Martin and White 2012; Dong et al. 2021a), with some specifically focused on the trenched/backfilled pipeline-soil interactions (e.g., Chaloulos et al. 2015; Kianian et al. 2018; Kianian and Shiri 2020, 2021; Dong et al. 2021b). As in these studies, the pipeline is considered to be rigid and the focus is on the soil properties and the magnitude of the soil resistance. One example can be made out of Guo (2005), which focuses on retrieving the horizontal-vertical (p-q) load space for buried pipes using a series of experiments and verifying it with continuum FE analyses.
