Shear-Wave Velocity to Evaluate In-Situ State of Ottawa Sand

The initial state of a sand, defined by the void ratio and effective mean normal stress, can be used to predict its large-strain response. Laboratory studies have shown that the shear-wave velocity of a sand is controlled primarily by the effective confining stresses and void ratio. Since shear-wave velocity can be measured both in the field and in the laboratory, there is an increasing interest in using shear-wave velocity to define the state of a sand. This paper presents an experimental study of shear-wave velocity interpretation for clean Ottawa sand based on steady/critical state concepts. The results show that the large-strain behavior of Ottawa sand can be estimated using shear-wave velocity measurements combined with a knowledge of the in-situ effective stress. Knowledge of the state of a sand makes it possible to estimate the boundary between either a contractant or dilatant sand at large strains. Based on these findings, a preliminary method to evaluate the potential for flow liquefaction using shear-wave velocity measurements is presented.