Abstract
Rock damage caused by its microcrack growth has a great influence on the deformation and strength properties of rock under compressive loading. Considering the interaction of wing cracks and the additional stress caused by rock bridge damage, a new calculation model for the mode-I stress intensity factor at wing crack tip was proposed in this study. The proposed calculation model for the stress intensity factor can not only accurately predict the cracking angle of wing crack, but can also simulate the whole range of variation of wing crack length from being extremely short to very long. Based on the modified stress intensity factor, a macro–micro damage model for rock materials was also established by combining the relationship between microcrack growth and macroscopic strain. The proposed damage model was verified with the results from the conventional triaxial compression test of sandstone sample. The results show that the proposed damage model can not only continuously simulate the stress-strain curves under different confining pressures, but also can better predict the peak strength. Furthermore, the sensitivities of initial crack size, crack friction coefficient, fracture toughness, initial damage and parameter m on the stress-strain relationship are discussed. The results can provide a theoretical reference for understanding the effect of microcrack growth on the progressive failure of rock under the compressive loading.
Highlights
Rock materials are heterogeneous bodies that composed of a variety of mineral grains, cements, microcracks
The wing crack models proposed by Horri and Nemat-Nasser [1,2] and Ashby and Hallam [3] can better describe the initiation and propagation process of cracks, and are gradually used to study the mechanical and deformation properties of rock materials
Wing crack model is the basis for studying the initiation, propagation, interaction and coalescence of compression–shear crack in rock materials
Summary
Citation: Peng, Z.; Zeng, Y.; Chen, X.; Cheng, S. A Macro–Micro Damage Model for Rock under Compression Loading. Appl. Sci. 2021, 11, 12154. https://doi.org/10.3390/ app112412154 Received: 15 November 2021 Accepted: 14 December 2021 Published: 20 December 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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