Micromechanical modelling of short- and long-term behavior of saturated quasi-brittle rocks. (March 2020)

• Record Type: Journal Article
• Authors: Yuan, Shuang-Shuang; Zhu, Qi-Zhi; Zhao, Lun-Yang; Chen, Liang; Shao, Jian-Fu; Zhang, Jin
• Is Part Of: Mechanics of materials. Volume 142(2020)
• Publication Date: 2020-03
• Subjects: Hydromechanical behavior -- Short- and long-term deformation -- Damage-friction coupling -- Micromechanics -- Effective stress -- Quasi-brittle rocks; Strength of materials -- Periodicals; Mechanics, Applied -- Periodicals; Résistance des matériaux -- Périodiques; Mécanique appliquée -- Périodiques; Mechanics, Applied; Strength of materials; Periodicals; Electronic journals; 620.11
• DOI: 10.1016/j.mechmat.2019.103298
• Languages: English
• ISSNs: 0167-6636

Abstract

Highlights: A micromechanical model is presented for describing the short and long term behavior of saturated rocks. The effect of pore pressure is consider ed in the friction criterion through the local effective stress. The short and long term strength of saturated brittle rocks are analytically deduced. Using the long term strength, the creep parameter can be related to characteristic stress. Abstract: This paper presents a physically-motivated micromechanical damage model for describing short- and long-term behaviors of saturated quasi-brittle rocks under drained condition. Rocks are considered composed of a pores-weakened elastic solid matrix and distributed microcracks. The system free energy is determined with the Mori-Tanaka homogenization method. Two main dissipative mechanisms, inelastic deformation due to frictional sliding and damage by crack propagation, are involved and strongly coupled in both stress-loading phases and creep phases under constant stresses. The effect of pore pressure is taken into account in the damage-friction coupling context. The microcracks induced rock damage is divided into two parts: instantaneous damage related directly to stress-induced microcrack growth, and time-dependent damage caused by subcritical cracking. The short- and long-term strengths of saturated brittle rocks are analytically deduced by damage-friction coupling analysis. By using the long-term strength, the creep parameter is calibrated in terms of a critical stress state identified in experiment. Comparisons between model's predictions and laboratory tests are performed for two typical quasi-brittle rocks under triaxial compression tests and triaxial compression creep tests. It is shown that the proposed model can capture the main features of the mechanical behavior of quasi-brittle materials.