Signature of Anisotropy in Liquefiable Sand Under Undrained Shear

This paper presents a study on the anisotropic behavior of liqufiable sand subjected to undrained shear, by using a 3D Discrete Element Method with two different approaches describing particle rolling. By using a sliding and free-rolling model, the force network in relation to anisotropy in medium-loose or dense samples presents a clear bimodal character, while the liquefiable loose specimen behaves differently. Appreciable degree of anisotropy is found developed in the weak force network when the sample tends to liquefy. When the rolling resistance is considered, all samples show marked increases in anisotropy in both the weak and strong force networks as well as the overall shear strengths, as compared with the free-rolling case. The loose sample tends also to be more resistant to liquefaction in the latter case than in the free rolling case under otherwise similar conditions.