Yongwei Li

Master of Science, St Hugh's College, University of Oxford, Trinity Term 2015

Lateral Buckling of On-­bottom Pipelines in Sand

Recent oil and gas developments in remote offshore locations require the construction of long seabed pipelines that operate under high temperature and pressure. Stress induced by thermal expansion of unburied seabed pipelines causes buckling and lateral deformation of the pipeline, which can damage the pipe and affect its overall integrity. A cost-effective design is to relieve the stress through controlled lateral buckling, which requires accurate and reliable assessment of the lateral resistance of pipe-soil interface.
Previous investigating of pipe-soil interface behaviour refers to the following 4 aspects: 1) the initial embedment of pipeline at installation, 2) breakout resistance during buckle formation, 3) Large amplitude displacement as buckle takes place; and 4) reduction effect in stability due to cyclic loading. This study aims at developing a better understanding of the pipe-soil interaction system in terms of lateral stability. To analyse and predict the pipe-soil response, a series of laboratory tests were conducted on a loose dry sand bed. Three types of load-controlled/displacement-controlled tests, namely 1) penetration test, 2) side swipe test and 3) probe test were designed and conducted to estimate the influence of the key parameters on the lateral buckling resistance of a shallowly embedded pipe in sand.

Thesis (24.6Mb, pdf)