New strain energy-based coupled elastoplastic damage-healing formulations accounting for effect of matric suction during earth-moving processes

摘要

Innovative initial elastic strain energy-based coupled elastoplastic hybrid isotropic damage and healing models for partially saturated soils have been developed and implemented for numerical simulation of two-dimensional earth-pushing processes. A class of elastoplastic constitutive damage-healing models, based on a continuum thermodynamic framework, is proposed within an initial elastic strain energy-based formulation. In particular, the change of effective stress caused by matric suction in the formulation is considered, and the governing incremental damage and healing evolutions are coupled and characterized through the effective stress concept in conjunction with the hypothesis of strain equivalence. Further, plastic flow is introduced by means of an additive split of the stress tensor. In this innovative formulation, two characteristic energy norms of the tensile and compressive strain tensors, respectively, are introduced for the corresponding damage and healing mechanisms. By incorporating a micromechanics-motivated damage characterization (P~+) and a healing characterization (P~-), the proposed model and computational algorithms have been implemented to demonstrate the significant flexibility on numerical simulation of earth-pushing processes. Completely new computational algorithms are systematically developed based on the two-step operator splitting methodology. The elastic-damage-healing predictor and the plastic corrector are implemented within the existing reproducing kernel particle method mesh-free codes. A numerical example under soil pushing is presented to illustrate the effect of matric suction for partially saturated soils or granular materials.