Residual strength after liquefaction: A rheological approach

The motion of a sphere pulled through liquefied sand of low relative density has been observed. Long triaxial specimens were prepared around a 12.7 mm-diameter sphere loaded by a wire/deadweight system. Velocities and drag forces were measured over a large range of shear strains and strain rates. Typical behavior involved a rapid drop to a non-zero minimum drag resistance followed by an increase in resistance with velocity. These results suggest that residual strength of sand after liquefaction is rate-dependent, and that the Bingham Plastic model seems a reasonable fit to the observed behavior over a large range of sliding velocities. Shear stresses calculated from the hydrodynamics of the sphere are of the same order as those inferred from field case histories. (c) 2005 Elsevier Ltd. All rights reserved.