Large-deformation finite element analysis of pipe penetration and large-amplitude lateral displacement

TLDR

Seabed pipelines must accommodate thermal expansion through controlled lateral buckling and resist submarine slide damage, with lateral pipe–soil resistance strongly influencing overall pipeline response. The study investigates pipe penetration and lateral displacement using a large‑deformation finite element method. The analysis employs a large‑deformation finite element model that incorporates a softening rate‑dependent soil model. The results show that calculated soil flow mechanisms, pipe resistances, and trajectories agree with plasticity solutions and centrifuge tests, revealing that lateral resistance is governed by soil heave and berm formation, with light pipes rising and sliding at the berm base while heavy pipes dive and mobilize deep shearing zones, a behavior captured by an effective embedment concept that yields a power‑law relationship with normalized lateral resistance.

Abstract

Seabed pipelines must be designed to accommodate thermal expansion — which is commonly achieved through controlled lateral buckling — and to resist damage from submarine slides. In both cases, the pipe moves laterally by a significant distance and the overall pipeline response is strongly influenced by the lateral pipe–soil resistance. Here, the process of pipe penetration and lateral displacement is investigated using a large-deformation finite element method, with a softening rate–dependent soil model being incorporated. The calculated soil flow mechanisms, pipe resistances, and trajectories agree well with plasticity solutions and centrifuge test data. It was found that the lateral resistance is strongly influenced by soil heave during penetration and the berm formed ahead of the pipe during lateral displacement. For “light” pipes, the pipe rises to the soil surface and the soil failure mechanism involves sliding at the base of the berm. In contrast, “heavy” pipes dive downwards and a deep shearing zone is mobilized, expanding with continuing lateral movement. The different responses are reconciled by defining an “effective embedment” that includes the effect of the soil berm or wall ahead of the pipe. The relationship between normalized lateral resistance and effective embedment is well fitted using a power law.