Abstract Anisotropic rocks with oriented arrangement of minerals (AROAM) often exhibit complex mechanical behaviors under cyclic disturbances. To investigate the progressive failure characteristics and damage evolution of AROAM, this study used biotite–quartz schist as an example and conducted triaxial cyclic loading and unloading tests under different schistosity angles and confining pressures. Additionally, CT scanning and numerical simulations were employed to systematically analyze the failure modes, crack propagation modes, and damage evolution characteristics of rocks. The results indicated that the macroscopic failure mode of the rock is significantly influenced by schistosity. As the schistosity angle increases, the failure mode of rocks shifts from tensile–shear to shear failure. The 45° schistosity promotes shear crack propagation, whereas the 0° schistosity is more prone to tensile crack formation. However, increasing confining pressure leads all macroscopic failure modes to transition toward shear failure. During damage evolution, crack propagation shows a directional clustering effect, which is most pronounced at a 45° schistosity angle and weakest at 90°. At a 0° schistosity angle, cracks undergo tensile expansion, making them more sensitive to confining pressure. Under cyclic loading and unloading, the overall damage level of the rock initially decreases and then increases with increasing schistosity angle. In the early stages (1–2 cycles), damage initially increases and then decreases with increasing schistosity angle. Moreover, higher confining pressure effectively suppresses damage accumulation in the rock. This study offers valuable insights into the progressive failure process and damage characteristics of AROAM when subjected to cyclic disturbances, including underground excavation, tunnel construction, and reservoir impoundment or drawdown. Highlights <UnorderedList Mark="Bullet"> <ItemContent> Schistosity structure dictates rock’s fracture modes and crack development. </ItemContent> <ItemContent> Schistosity structure significantly affects the number and evolution of rock fractures. </ItemContent> <ItemContent> Schistosity structure alters the progression and severity of rock damage. </ItemContent> <ItemContent> Mineral arrangement and stress jointly influence the failure mode of rock. </ItemContent> </UnorderedList>

Progressive Failure Characteristics and Damage Evolution of Anisotropic Rocks with Oriented Arrangement of Minerals Under Triaxial Cyclic Loading and Unloading

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发表日期：

2026年1月12日

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Dahai Wang,
Changqing Liu,
Han Bao,
Hengxing Lan,
Peng Sha,
Bo Li,
Shijie Liu,
Changgen Yan

摘要

Abstract

Anisotropic rocks with oriented arrangement of minerals (AROAM) often exhibit complex mechanical behaviors under cyclic disturbances. To investigate the progressive failure characteristics and damage evolution of AROAM, this study used biotite–quartz schist as an example and conducted triaxial cyclic loading and unloading tests under different schistosity angles and confining pressures. Additionally, CT scanning and numerical simulations were employed to systematically analyze the failure modes, crack propagation modes, and damage evolution characteristics of rocks. The results indicated that the macroscopic failure mode of the rock is significantly influenced by schistosity. As the schistosity angle increases, the failure mode of rocks shifts from tensile–shear to shear failure. The 45° schistosity promotes shear crack propagation, whereas the 0° schistosity is more prone to tensile crack formation. However, increasing confining pressure leads all macroscopic failure modes to transition toward shear failure. During damage evolution, crack propagation shows a directional clustering effect, which is most pronounced at a 45° schistosity angle and weakest at 90°. At a 0° schistosity angle, cracks undergo tensile expansion, making them more sensitive to confining pressure. Under cyclic loading and unloading, the overall damage level of the rock initially decreases and then increases with increasing schistosity angle. In the early stages (1–2 cycles), damage initially increases and then decreases with increasing schistosity angle. Moreover, higher confining pressure effectively suppresses damage accumulation in the rock. This study offers valuable insights into the progressive failure process and damage characteristics of AROAM when subjected to cyclic disturbances, including underground excavation, tunnel construction, and reservoir impoundment or drawdown.

Highlights

Schistosity structure dictates rock’s fracture modes and crack development.

Schistosity structure significantly affects the number and evolution of rock fractures.

Schistosity structure alters the progression and severity of rock damage.

Mineral arrangement and stress jointly influence the failure mode of rock.