Offshore pipelines are usually buried in a trench and covered by pre-excavated materials for physical protection. Large lateral displacement of trenched pipelines may be induced by mechanisms such as ground movement and ice gouging. The different soil properties between the backfilling material and the native ground may significantly influence the soil deformations and failure mechanisms around the pipe and affect the ultimate response of lateral displaced pipeline. Existing pipeline design codes ignore trench effects on the lateral pipe response and commonly use the undrained shear strength to assess the ultimate pipe-soil interaction force. Drained or partially drained conditions are quite common in real pipe-soil interaction events, and the soils surrounding the pipeline may benefit from consolidation during the pipe movement. In this study, first, the 2D remeshing and interpolation technique with small strain model (RITSS) was developed in ABAQUS for a LDFE framework. The pipeline-backfill-trench interaction was investigated. Then the developed model was extended to incorporate coupled consolidation analysis, accounting for excess pore pressure generation and dissipation. The study reveals a significant impact of the trench and consolidation on soil deformation, failure mechanism, and the pipe-soil lateral interaction force.
Xiaoyu Dong, Hodjat Shiri, Wangcheng Zhang and Mark F. Randolph
Keywords: Trench, Pipeline-soil interaction, Large deformation, Numerical modeling, Coupled analysis
Publisher: DFI