Strength reduction for upheaval buckling of buried pipes in blocky clay backfill

Andrew John Brennan (Lead / Corresponding author), Mahmoud Ghahremani, Michael John Brown

Research output: Contribution to journalArticle

5 Citations (Scopus)
302 Downloads (Pure)

Abstract

Offshore pipelines are often buried to protect the pipeline from external loads and upheaval buckling. Models for pipe uplift resistance in clay soils are based predominantly on homogenous backfill conditions. In practice, however, there will be significant soil disturbance during installation. With certain trenching techniques this may produce a backfill more akin to a matrix of lumps of intact soil connected by weaker remoulded interfaces. This research uses centrifuge modelling to assess the resistance provided by a representative lumpy clay backfill that has experienced self-weight consolidation. A model pipe is then uplifted through this model backfill in order to assess the soil uplift resistance. Results show that the uplift resistance in this material is governed strongly by the size of the lumps and, to a lesser extent, by the rate at which displacement occurs. When interpreted in terms of the strength reduction η, that may be used to correct between theoretical and measured uplifts, lower values were derived than those currently used based on intact soils. The value of η is seen to be controlled by a non-dimensional drainage parameter, but may be practically estimated based on an estimate of the size of lumps relative to the pipe diameter.
Original languageEnglish
Pages (from-to)210-217
Number of pages8
JournalOcean Engineering
Volume130
Early online date8 Dec 2016
DOIs
Publication statusPublished - 15 Jan 2017

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  • Research Output

    • 5 Citations
    • 1 Conference contribution

    Development of a series of 2D backfill ploughing physical models for pipelines and cables

    Bizzotto, T., Brown, M., Brennan, A., Powell, T. & Chandler, H. W., Jul 2018, Physical Modelling in Geotechnics: Proceedings of the 9th International Conference on Physical Modelling in Geotechnics (ICPMG 2018), July 17-20, 2018, London, United Kingdom. McNamara, A., Divall, S. & Goodey, R. (eds.). 1 ed. Taylor & Francis, p. 553-558 4 p.

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    Open Access
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