Evaluation of viscoplastic slope movement based on triaxial tests

Viscoplastic soil parameters are used in a nonlinear viscoplastic constitutive model to predict time-dependent displacement of slow-moving landslides. The viscoplastic material parameters are determined by a novel method that uses a standard triaxial apparatus. This method employs data obtained from consolidated drained triaxial tests and consolidated drained stress-controlled strain-rate tests. The methodology was applied to undisturbed samples from the Minor Creek landslide in the Franciscan Terrane of northern California. Viscoplastic parameters determined from the laboratory tests were combined with boring log data to calculate the landslide’s vertical velocity profile. This profile provided a reasonable match to a measured velocity profile obtained from repetitive inclinometer surveys.