Three-dimensional UH model for structured soils considering bonding

In order to reflect the influences of bonding in structured soils on the ultimate shear stress ratio and dilatancy law, a dynamic moving critical state line (MCSL), which parallels to the traditional static critical state line (CSL) and moves to the CSL as bonding structure decays, is introduced in p-q stress space. Correspondingly, the yielding surfaces and the dilatancy equation are both modified to match the MCSL. After that, a UH model for structured soils considering bonding is developed from the structured UH model mainly considering soil structure collapse. Adopting the transformed stress method, the proposed model is developed to be applied in three-dimensional stress space. Compared to the structured UH model, the proposed new model adds only 1 model parameter expressing the initial bonding level, which can be estimated by unconfined compression tests. Comparisons between test data and model predictions of 4 structured soils indicate that the proposed model is qualified in reasonably describing the behaviors of the bonding structured soils in isotropic compression, drained/undrained triaxial compression and true triaxial shear.