Shear failure behaviors and degradation mechanical model of rockmass under true triaxial multi-level loading and unloading shear tests

作者：Zhi Zheng, Ronghua Li, Peng‐Zhi Pan, Jinghua Qi, Guoshao Su, Hong Zheng · 发表于：International Journal of Mining Science and Technology · 年份：2024 · DOI：10.1016/j.ijmst.2024.10.002 · 被引用次数：49 · 研究领域：Rock Mechanics and Modeling、Geomechanics and Mining Engineering、Geotechnical and Geomechanical Engineering

The redistribution of three-dimensional (3D) geostress during underground tunnel excavation can easily induce to shear failure along rockmass structural plane, potentially resulting in engineering disasters. However, the current understanding of rockmass shear behavior is mainly based on shear tests under 2D stress without lateral stress , the shear fracture under 3D stress is unclear, and the relevant 3D shear fracture theory research is deficient. Therefore, this study conducted true triaxial cyclic loading and unloading shear tests on intact and bedded limestone under different normal stress σ n and lateral stress σ p to investigate the shear strength, deformation, and failure characteristics. The results indicate that under different σ n and σ p , the stress–strain hysteresis loop area gradually increases from nearly zero in the pre-peak stage, becomes most significant in the post-peak stage, and then becomes very small in the residual stage as the number of shear test cycles increases. The shear peak strength and failure surface roughness almost linearly increase with the increase in σ n , while they first increase and then gradually decrease as σ p increases, with the maximum increases of 12.9% for strength and 15.1% for roughness. The shear residual strength almost linearly increases with σ n , but shows no significant change with σ p . Based on the acoustic emission characteristic parameters during the test process, the shear fracture process and microscopic failure m...