Estimating the undrained strength of sand: a theoretical framework

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  • Abstract: A framework for estimating the ultimate undrained steady state shear strength of sand (S-u) from in situ tests, which combines the theory of critical state soil mechanics with shear wave velocity measurements, is presented. For a particular direction of undrained loading, samples of a given sand at a constant void ratio will reach the same S-u, despite the magnitude of the initial effective confining stresses. Unique S-u/p' or S-u/sigma'(v) ratios for a given direction of loading exist for a particular sand only if state parameter is constant throughout the deposit. Normalized shear wave velocity, V-s1, can be correlated with void ratio and is therefore used to estimate S-u for a given initial state and direction of loading. Strengths in triaxial compression are examined in this paper; however, the same framework can be used to estimate strengths under other directions of loading. The S-u-V-s1 relationship is shown to be relatively sensitive and should be used more as a screening tool rather than an accurate means of predicting S-u. V-s1 is converted to equivalent values of SPT (N-1)(60) and CPT q(c1), and the results are compared with the current methods of estimating S-u.

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    Article (Published)
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    © 1995 NRC Research Press (Canadian Science Publishing. This version of this article is open access and can be downloaded and shared. The original author(s) and source must be cited.
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    • Fear, C. E., & Robertson, P. K. (1995). Estimating the undrained strength of sand: a theoretical framework. Canadian Geotechnical Journal, 32(5), 859-870. DOI: 10.1139/t95-082.