Geotechnical and Rheological Characteristics of Saguenay Fjord Sediments Near the Transition from Solid to Liquid

Abstract

This paper examines the geotechnical and rheological characteristics in terms of the transition from slide to flow in submarine landslides. This paper contains the results of a series of laboratory tests on the Saguenay Fjord fine-grained sediments. There are two types of tests: (1) vane shear tests in which intact and remolded samples are sheared and exposed to ambient water and (2) rheological tests performed on remolded sediment (with variable liquidity index) using a viscometer. The results explain the effect of water infiltration into soil. The sudden reduction in shear strength varied between about 300 and 800 Pa (Δw = 2–20%). The viscosity obtained from normalized flow curves (i.e., the logarithmic plot of shear stress versus the shear rate) were employed to characterize the rheology of soil. The mean value of viscosity (strength parameter in this case) as a function of shear rate from the results of fine-grained sediments varied between about 0.1 and 0.4. The values of yield stress and viscosity that were associated with the passage from the remolded to the fluidized state were in the range of 200 to 300 for Saguenay Fjord sediments.

Keywords:

• fine-grained sediments
• normalized flow curve
• Saguenay Fjord
• submarine landslides
• viscosity
• water infiltration

Acknowledgment

The authors are indebted to anonymous reviewers for their valuable comments and recommendations.

Notes

Note. * = mean value. CF (%) = clay fraction; I _p = plasticity index (%); S = salinity (g/L); SS = Specific area (m²/g); w _L = liquid limit (%); w _n = water content (%); and w _p = plastic limit (%). Geotechnical data were compiled by Jeong (2006).

Note. P (cm) = penetration depth of vane blade; sat. = time of saturation (hours); w _n = natural water content; ΔC_ur = variation in undrained shear strength (kPa) from stage III to stage IV; and Δw = variation in water content from stage III to stage IV.

Note. I_L = liquidity index; n = power law index; α_v = strength parameter obtained from normalized flow curve (dimensionless); τ_c-B and τ_c-BH = Bingham and Herschel-Bulkley yield stress (Pa), respectively; η_h = Bingham viscosity (mPa · s); and K = flow consistency index (Pa · s).

Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/umgt.