Influence of drying-wetting cycles and soaking conditions on the shear creep characteristics of sandstone joints
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Graphical Abstract
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Abstract
Numerous slope failures have been reported during periods of water level fluctuations. Understanding the influence of water on the creep behavior of joints is essential for evaluating the long-term stability of slopes. This study focuses on the effects of drying-wetting cycles and soaking conditions on the long-term behavior of sandstone joints. A total of 12 multi-stage shear creep tests are carried out on sandstone joints subjected to varying drying-wetting cycles under both soaking and un-soaking conditions. Based on the experimental results, the influences of drying-wetting cycles as well as soaking conditions on the microstructure, shear creep displacement, strength, and failure morphologies of sandstone joints are investigated comprehensively. Results indicate that increasing drying-wetting cycles not only yields larger shear creep displacements but also leads to a negative exponential decrease in the strength of sandstone joints. Besides, soaking conditions strongly influence the creep behavior of sandstone joints. The failure strength and long-term strength of sandstone joints for soaked samples decrease by 13.6%–29.0% and 19.4%–37.5%, respectively, as compared to unsoaked samples. Furthermore, four distinct stages in the shear creep process were identified according to the results obtained from multi-stage shear creep tests and computerized tomography scans, and three creep failure modes of sandstone joints are thus determined. Finally, the influence mechanism of drying-wetting cycles and soaking conditions on the creep failure modes of sandstone joints is revealed. Drying-wetting cycles and soaking conditions diminish the influence of asperities on the shear creep behavior of joints, thereby reducing the resistance of joints to long-term deformation.
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