Effects of stress on failure behaviour of shallow-marine muds from the northern Gulf of Mexico

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doi: 10.1144/SP477.13
Author(s): Dugan, Brandon; Zhao Xin
Author Affiliation(s): Primary:
Colorado School of Mines, Department of Geophysics, Golden, CO, United States
Other:
Shanghai Winners Education Consulting Company, China
Volume Title: Subaqueous mass movements and their consequences; assessing geohazards, environmental implications and economic significance of subaqueous landslides
Volume Author(s): Lintern, D. G., editor; Mosher, David C.; Moscardelli, L. G.; Bobrowsky, P. T.; Campbell, C.; Chaytor, J. D.; Clague, J. J.; Georgiopoulou, A.; Lajeunesse, Patrick; Normandeau, Alexandre; Piper, David J. W.; Scherwath, M.; Stacey, C.; Turmel, D.
Source: Subaqueous mass movements and their consequences; assessing geohazards, environmental implications and economic significance of subaqueous landslides, edited by D. G. Lintern, David C. Mosher, L. G. Moscardelli, P. T. Bobrowsky, C. Campbell, J. D. Chaytor, J. J. Clague, A. Georgiopoulou, Patrick Lajeunesse, Alexandre Normandeau, David J. W. Piper, M. Scherwath, C. Stacey and D. Turmel. Special Publication - Geological Society of London, Vol.477. Publisher: Geological Society of London, London, United Kingdom. ISSN: 0305-8719 CODEN: GSLSBW
Note: In English. 45 refs.Online First; illus., incl. 1 table, sketch maps
Summary: Direct simple shear experiments on mud samples from 0 to 15 mbsf (metres below seafloor) in the Ursa Basin (northern Gulf of Mexico) document that stress level impacts shear strength and pore pressure during failure. As burial depth increased (from 7.35 to 13.28 mbsf), cohesion decreased (from 12.3 to 6.5 kPa) and the internal friction angle increased (from 18° to 21°). For a specimen from 11.75 mbsf, an increase in maximum consolidation stress (from 45 to 179 kPa) resulted in an increase in the shear-induced pore pressure (from 29 to 150 kPa); however, the normalized peak shear stress decreased (from 0.37 to 0.25). Our results document that consolidation at shallow depths induces a positive feedback on pore-pressure genesis. For resedimented samples, which lack a stress history, cohesion was 3.6 kPa and the internal friction angle was 24°. As the maximum consolidation stress increased (from 40 to 254 kPa) on resedimented samples, the shear-induced pore pressure increased (from 22 to 203 kPa), whereas the normalized peak shear stress decreased (from 0.32 to 0.25). Our experiments showed that resedimented samples have similar strength and failure behaviour to intact samples. By constraining pore pressure, strength and initial stress state, we gain a better insight into slope-failure dynamics. Therefore, our experiments provide constraints on strength and shear-induced pore pressure at the onset of shallow failure that could be included in slope-failure and hazard models.
Year of Publication: 2018
Key Words: 07 Marine Geology and Oceanography; 30 Engineering Geology; Atlantic Ocean; Bathymetry; Clastic sediments; Deposition; Effects; Engineering properties; Equations; Errors; Experimental studies; Fabric; Failures; Friction angles; Gulf of Mexico; Marine environment; Marine sediments; Mass movements; Mississippi Canyon; Mud; North Atlantic; Pore pressure; Porosity; Samples; Sedimentation; Sediments; Shallow-water environment; Shear; Shear strength; Shear stress; Slope stability; Strain; Strength; Stress; Uncertainty; Ursa Basin
Coordinates: N280000 N281200 W0890000 W0891200
Record ID: 2018052729
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from The Geological Society, London, London, United Kingdom