Constitutive modeling of artificially cemented sand by considering fabric anisotropy

Artificially cemented sand has been widely used in practical applications relevant to soil improvement and liquefaction mitigation. It has also been frequently used in laboratory tests to simulate the cementation and bonding formed in naturally structured sand. Known to be difficult to characterize, the behavior of artificially cemented sand is typically affected by its internal structure consisting of both bonding and fabric. In this study, a novel constitutive model is proposed to describe the effect of bonding and fabric anisotropy on the behavior of artificially cemented sand. We choose the triaxial tensile strength as a macroscopic representation of the inter-particle bonding, and a fabric tensor to characterize the fabric in sand. The yield function adopted in the model is an extension of a recently developed anisotropic failure criterion, with the frictional parameter therein being replaced by a proper hardening parameter. A de-bonding law is proposed by assuming the de-bonding process is driven by the development of plastic deformation. The soil fabric is kept constant in the study to account for inherent anisotropy. Relevant model parameters can be conveniently calibrated by conventional laboratory tests. The model is employed to predict the behavior of cemented Ottawa sand and multiple-sieving-pluviated Toyoura sand, and the predictions compare well with the experimental data.