Rock and Soil Mechanics ›› 2023, Vol. 44 ›› Issue (12): 3541-3550.doi: 10.16285/j.rsm.2023.5538

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Strength model of anisotropic rocks based on Hoek-Brown criterion

LI Guo-xiao1, 2, WANG Hang-long1, PENG Jun2, WANG Lin-fei2, DAI Bi-bo2   

  1. 1. Faculty of Land and Resources Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650093, China 2. State Key Laboratory of Safety and Health for Metal Mines, Sinosteel Maanshan Institute of Mining Research Co., Ltd., Maanshan, Anhui 243000, China
  • Online:2023-12-20 Published:2024-02-07
  • Contact: PENG Jun, male, born in 1986, PhD, Professor, research interests: deep rock mechanics and rock mass disaster prevention and control. E-mail:
  • About author:LI Guo-xiao, male, born in 1994, Master’s student, focusing on rock mechanical properties.
  • Supported by:
    the National Key Research and Development Plan for Young Scientists (2022YFC2905700), the Key Project of National Natural Science Foundation of China (52130403), the Natural Science Foundation of Anhui Province (2208085ME120) and the Key Research and Development Plan of Anhui Province (2022m07020001).

Abstract: In order to improve the applicability of Hoek-Brown failure criterion and reduce subjectivity in the determination of geological strength index (GSI) value for anisotropic rocks, a modified Hoek-Brown failure criterion is proposed, which considers the variation of the GSI value with the bedding angle of anisotropic rocks. Triaxial compression test data of anisotropic rocks with different bedding angles were first collected. The results show that the peak strength of anisotropic rocks exhibits a U-shaped relation with bedding angle . Then, the rock specimen with the bedding angle  = 0º is defined as the intact rock. The uniaxial compressive strength c and material parameter mi of intact rocks are obtained from data fitting using Hoek-Brown failure criterion. The corresponding GSI values under different bedding angles are calculated. The relationship between GSI and bedding angle  is fitted using Gaussian function, and a new strength model of anisotropic rocks is established based on Hoek-Brown failure criterion. Finally, the proposed model is verified by comparing the peak strength obtained from the GSI-softening model. It is found that the modified Hoek-Brown failure criterion is suitable for predicting the strength of anisotropic rocks with different bedding angles and under various confining pressure. The physical meaning of the new parameters in the model is also discussed.

Key words: anisotropic rock, bedding angle, Hoek-Brown failure criterion, GSI-strength model