Back analysis of the Nerlerk berm liquefaction slides

Five liquefaction slides occurred in 1983 during the construction of a hydraulically placed subsea sand berm designed to form part of a bottom-founded, offshore, hydrocarbon exploration platform at Nerlerk in the Canadian Beaufort Sea. These slides were triggered by simple static loading arising fro...

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Bibliographic Details
Published in:Canadian Geotechnical Journal
Main Authors: Sladen, J. A., D'Hollander, R. D., Krahn, J., Mitchell, D. E.
Format: Article in Journal/Newspaper
Language:English
Published: Canadian Science Publishing 1985
Subjects:
Online Access:http://dx.doi.org/10.1139/t85-077
http://www.nrcresearchpress.com/doi/pdf/10.1139/t85-077
Description
Summary:Five liquefaction slides occurred in 1983 during the construction of a hydraulically placed subsea sand berm designed to form part of a bottom-founded, offshore, hydrocarbon exploration platform at Nerlerk in the Canadian Beaufort Sea. These slides were triggered by simple static loading arising from the sand placement itself. Failures started at locally oversteepened side slopes and retrogressed to form bowl-shaped crests. The slide material came to rest beyond the berm at very flat slopes. Stability back analyses reveal that effective stress strength parameters consistent with limiting equilibrium are within the range of the collapse surface parameters determined from triaxial laboratory tests. This finding lends credibility to the collapse surface concepts introduced in another study. Back calculations show that the berm state prior to failure was much looser than the steady state, with the potential for a large strength loss. According to back calculations, the berm density was lower than that inferred from cone penetration tests. Key words: liquefaction, sand, hydraulic fill, slope stability, cone penetration testing.