Effect of the Mode of Shear on Static Liquefaction Analysis

Abstract

The current practices for determining the peak (yield) and postliquefaction (critical) undrained shear strength of liquefiable cohesionless soils for grounds subject to static shear stress (e.g., sloping grounds or grounds beneath foundations) require either a suite of costly laboratory shear tests on undisturbed field samples or empirical correlations with in situ penetration tests, which do not account for the effect of the shearing mode on soil behavior. Improved correlations are developed in this study for estimating the undrained triggering and postliquefaction shear strengths of cohesionless soils, which are based on the most reliable field-liquefaction data from past cases of liquefaction flow failures and soil shearing behavior observed in a large database of 600 laboratory shear tests for different modes of shear. The proposed method accounts for the variations in the mode of shear when providing estimates of the undrained triggering and postliquefaction strengths mobilized in static liquefaction flow failures.