Pipe–Soil Interaction with Large Lateral Movement on Undrained Clay: An LDFE Analysis

A critical design challenge for pipelines laid directly on the seabed in deepwater is comprehending and, consequently, managing the effects of thermal- and pressure-induced lateral buckling for both light and heavy pipes. To ensure the lateral buckling occurs as planned, this paper presents a comprehensive study, using the large-deformation finite-element (LDFE) method, on pipe–soil interactions with large lateral movements on an undrained clay seabed. Both strain softening and rate effects are considered in the LDFE analysis. The LDFE method is validated against existing centrifuge test data. Then, a comprehensive parametric study is conducted, involving variations in pipe weight, initial embedment, strain softening, and rate effects. It is discovered that to distinguish between light and heavy pipe behaviors, a unique critical pipe weight factor can be employed. Both light and heavy pipes with large lateral movements are investigated. The light pipes showed a peak resistance at initial breakout stage, then reached their residual resistance without burial. The heavy pipes have two categories: medium-heavy pipes and heavy pipes. The medium-heavy pipes showed no self-burial, and their resistances increased sharply at initial stage and then gradually reached a constant. The heavy pipes showed a self-burial tendency with large lateral movement as they dove deeper. Hence, their resistances kept increasing with lateral movement. A simple prediction model for pipe–soil interactions with large lateral movements is proposed based on the newly proposed critical pipe weight factor.