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Numerical simulation of true triaxial unilateral unloading effect of fractured rock

Chao Zhang, Jianxin Fu, Yu Wang

Engineering Computations

ISSN: 0264-4401

Article publication date: 5 September 2023

Issue publication date: 5 December 2023

197

Abstract

Purpose

The interaction between rock mass structural planes and dynamic stress levels is important to determine the stability of rock mass structures in underground geotechnical engineering. In this work, the authors aim to focus on the degradation effects of fracture geometric parameters and unloading stress paths on rock mechanical properties.

Design/methodology/approach

A three-dimensional Particle Flow Code (PFC3D) was used for a systematic numerical simulation of the strength failure and cracking behavior of granite specimens containing prefabricated cracks under conventional triaxial compression and triaxial unilateral unloading. The authors demonstrated the unique mechanical response of prefabricated fractured rock under two conditions. The crack initiation, propagation, and coalescence process of pre-fissured specimens were analyzed in detail.

Findings

The authors show that the prefabricated cracks and unilateral unloading conditions not only deteriorate the mechanical strength but also have significant differences in failure modes. The degrading effect of cracks on model strength increases linearly with the decrease of the dip angle. Under the condition of true triaxial unilateral unloading, the deterioration effect of peak strength of rock is very significant, and unloading plays a role in promoting the instability failure of rock after peak, making the rock earlier instability failure. Associating with the particle vector diagram and crack coalescence process, the authors find that model failure mode under unilateral loading conditions is obviously distinct from that in triaxial loading. The peak strain in the unloading direction increases sharply, resulting in a new shear slip.

Originality/value

This study is expected to improve the understanding of the strength failure and cracking behavior of fractured rock under unilateral unloading.

Keywords

Acknowledgements

Since acceptance of this article, the following authors have updated their affiliations: Chao Zhang and Jianxin Fu is at the State Key Laboratory of High-Efficient Mining and Safety of Metal Mines of Ministry of Education, University of Science and Technology Beijing, Beijing, China.

Citation

Zhang, C., Fu, J. and Wang, Y. (2023), "Numerical simulation of true triaxial unilateral unloading effect of fractured rock", Engineering Computations, Vol. 40 No. 9/10, pp. 2110-2128. https://doi.org/10.1108/EC-07-2022-0477

Publisher

:

Emerald Publishing Limited

Copyright © 2023, Emerald Publishing Limited

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