The Tangguh LNG subsea pipelines are susceptible to upheaval buckling (UHB), for which the primary mitigation was to trench and bury with quarried rock. To ensure a uniform level of reliability is achieved and also to optimise rock volumes, a full structural reliability analysis (SRA) was undertaken as an alternative to utilizing DNV-RP-F110. This paper summarises the analysis of full scale test results to evaluate uplift resistance, including the effects of thin layers of natural trench backfill, filter and armour rock layering. The testing also undertook enough tests to enable statistical measures of reliability to be found. The results of testing are compared with generic uplift models presented in DNV-RP-F110, with considerable improvements justified within well defined confidence intervals.
Snap behaviour in the upheaval buckling of subsea pipelines under topographic step imperfection