Huang Tianzhu, Wang Lehua, Li Jianlin, Zhang Bingyi, Wang Xiaoping, Xu Xiaoliang
Key Laboratory of Geological Hazards on Three Gorges Reservoir Area, Ministry of Education, China Three Gorges University, Yichang, 443002, Hubei, China.
College of Civil Engineering and Architecture, China Three Gorges University, Yichang, 443002, Hubei, China.
Sci Rep. 2022 Sep 27;12(1):16072. doi: 10.1038/s41598-022-20433-y.
To study the differences in mechanical properties and failure characteristics of underground chambers surrounding rock under different stress conditions, triaxial loading and unloading tests were carried out on argillaceous sandstone. The three-dimensional topography parameters of the fracture surface were obtained by using high-precision three-dimensional topography scanning technology, including six height characteristic parameters and two texture parameters. Compared with the triaxial loading test, the strength, peak strain and residual strength of argillaceous sandstone with the same confining pressure under unloading conditions all decrease, and the stress-strain curve changes from ductility to brittleness. The Mogi-Coulomb strength criterion can better describe the strength properties of argillaceous sandstones than the Mohr-Coulomb and Drucker-Prager strength criteria. Under the unloading condition, the cohesion c decreased by 30.87% and the internal friction angle φ increased by 30.87% compared with the loading condition. The tensile cracks perpendicular to the unloading direction is formed during unloading, resulting in large roughness, dispersion and fluctuation of fracture surface.
为研究不同应力条件下地下洞室围岩力学特性及破坏特征的差异，对泥质砂岩开展了三轴加卸载试验。采用高精度三维地形扫描技术获取了断层面的三维地形参数，包括六个高度特征参数和两个纹理参数。与三轴加载试验相比，相同围压下泥质砂岩在卸载条件下的强度、峰值应变和残余强度均降低，应力 - 应变曲线由延性转变为脆性。与摩尔 - 库仑强度准则和德鲁克 - 普拉格强度准则相比，莫吉 - 库仑强度准则能更好地描述泥质砂岩的强度特性。在卸载条件下，与加载条件相比，黏聚力c降低了30.87%，内摩擦角φ增加了30.87%。卸载过程中形成垂直于卸载方向的拉伸裂纹，导致断层面粗糙度大、离散性和起伏性强。
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