Rock and Soil Mechanics ›› 2022, Vol. 43 ›› Issue (8): 2060-2070.doi: 10.16285/j.rsm.2021.6833

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Progressive failure strength characteristics of anisotropic rocks caused by mineral directional arrangement: a case of biotite quartz schist

BAO Han1, CHEN Zhi-yang1, LAN Heng-xing2, PEI Run-sheng1, WU Fa-quan3, YAN Chang-gen1, TAO Yue1   

  1. 1. School of Highway, Chang’an University, Xi’an, Shaanxi 710064, China 2. Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China 3. School of Civil Engineering, Shaoxing University, Shaoxing, Zhejiang 312000, China
  • Online:2022-09-30 Published:2022-09-30
  • Contact: WU Fa-quan, male, born in 1955, PhD, Research scientist,PhD supervisor, research interests: theory and application of engineering geology and rock mechanics. E-mail: E-mail:
  • About author:BAO Han, male, born in 1988, PhD, Professor, mainly engaged in teaching and research work in geotechnical engineering and geological engineering.
  • Supported by:
    the National Natural Science Foundation of China (42177142, 41927806, 42041006), the Youth Talent Promotion Program of Xi'an Association for Science and Technology (095920201310), and the Fundamental Research Funds for the Central Universities, Chang’an University (300102212213).

Abstract: To explore the strength characteristics of anisotropic rocks caused by mineral directional arrangement during progressive failure process, biotite quartz schist was taken as an example, and triaxial compression tests were carried out on samples with schistosity angles of 0°, 45° and 90°. The macro and micro failure characteristics and progressive failure strength index of the specimens were analyzed, and the differences with other types of anisotropic rock were discussed. The results show that the failure characteristics of biotite quartz schist are closely related to its schistosity. With the schistosity angle increasing from 0° to 90°, the main macro and micro fracture modes of the specimens change from tensile to shear, and then to co-existence of tensile and shear. The strength characteristic values of biotite quartz schist show significant anisotropy. With the increase of schistosity angle, the strengthening effect caused by confining pressure increase on the strength characteristic values weakens, but the change of the strength value has a trend of acceleration. The anisotropic variation law of the ratio of strength characteristic value is not obvious, which gradually weakens and even disappears under high confining pressure. The fracture modes, variations of strength characteristic values and their ratios of anisotropic rocks with directional arrangement of minerals are different from those of rocks with stratified structure. A thorough understanding of the mechanical properties of rocks with directional arrangement of minerals will be helpful to guide the related engineering practice.

Key words: mineral directional arrangement, biotite quartz schist, progressive failure, characteristic value of strength, anisotropy