An extended micromechanical-based plastic damage model for understanding water effects on quasi-brittle rocks
Qiaojuan Yu, Shigui Du, Qizhi Zhu, Zhanyou Luo, Sili Liu, Lunyang Zhao
Abstract
Water effects on the mechanical properties of rocks have been extensively investigated through experiments and numerical models. However, few studies have established a comprehensive link between the microscopic mechanisms of water-related micro-crack and the constitutive behaviors of rocks. In this work, we shall propose an extended micromechanical-based plastic damage model for understanding weakening effect induced by the presence of water between micro-crack’s surfaces on quasi-brittle rocks, based on the Mori-Tanaka homogenization and irreversible thermodynamics framework. Regarding the physical mechanism, water strengthens micro-crack propagation, which induces damage evolution during the pre- and post-stage, and weakens the elastic effective properties of rock matrix. After proposing a special calibration procedure for the determination of model parameters based on the laboratory compression tests, the proposed micromechanical-based model is verified by comparing the model predictions to the experimental results. The model effectively captures the mechanical behaviors of quasi-brittle rocks subjected to the weakening effects of water.