Full-scale laboratory testing research to study the performance of offshore pipelines

Monday, December 21, 2009 | By
Full-scale pipe-soil interaction testing chamber at UBC

Dr. Dharma Wijewickreme of UBC Civil Engineering has been recently awarded a grant from the National Priority Research Program (NPRP) of Qatar National Research Fund (QNRF) to study the “Behaviour of Offshore Pipeline-soil Interface Using Full-scale Laboratory Testing.” The work will be undertaken in collaboration with Dr. Hisham Eid of Qatar University.

The performance of oil and gas pipeline systems under operational and/or natural loadings is an important engineering consideration for the energy industry since the failure of these systems due to such loadings are often associated with business, environmental, and safety related risks. One example in this regard is the need to evaluate the performance of offshore pipelines when subjected to potential differential movements due to thermal expansion or contraction under production and shut-in conditions. Such differential pipeline movements are typically associated with large strains in the soil at the pipe-soil interface. Since a very large proportion of the offshore pipelines are located essentially at the seabed level, these interface shear strains are developed under significantly low soil effective normal stress levels. For most seabed soil types, development of such strains can significantly reduce the pipe-soil interface strength and consequently affect the stability of pipelines placed on sloping sea floors and the potential of pipeline walking.

The proposed research supported by the QNRF grant will involve full-scale laboratory testing to understand the strength and deformation characteristics at soil-pipe interfaces under low effective normal stresses. The UBC soil-pipe interaction chamber that is currently used for studying various on-land soil-pipe interaction problems for full-scale simulation of soil-pipe interaction problems by Dr. Wijewickreme will serve as the central experimental tool for undertaking this work. Research findings from this work will directly contribute to the offshore pipeline industry in assessing the stability of pipelines placed on sloping sea floors. The outcomes are also expected to contribute to advancing the fundamental understanding of the mechanical behavior of soils.

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