弱胶结泥岩真三轴力学特性试验研究

Experimental Study on True-Triaxial Mechanical Properties of Weakly Cemented Mudstone

摘要: 我国西部矿区广泛分布弱胶结泥岩，其胶结性差、结构松散，在采动扰动下易发生变形破坏，严重威胁矿井安全。为揭示中主应力对其力学行为的影响机制，以内蒙古塔拉壕煤矿底板泥岩为研究对象，开展真三轴加载试验，分析不同中主应力比(σ₂/σ₃)下岩样的应力–应变演化特征、强度规律及破坏模式。结果表明：弱胶结泥岩峰值强度与中主应力比呈显著正相关，随着σ₂/σ₃增大，峰值强度提高了45.43%；弹性模量随σ₂/σ₃增大呈先增后减特征，并在1.5~2.0区间达到最大；岩样破裂面规整性随σ₂/σ₃增大而降低，破坏形态趋于复杂化。强度准则对比显示，Mogi-Coulomb准则对试验数据的拟合效果最佳，其决定系数R²达到0.9793。研究结果可为西部矿区深部巷道支护设计及数值模拟参数选取提供依据。

Abstract: Weakly cemented mudstone is widely distributed in mining areas of western China. It is characterized by poor cementation and loose structure, and is prone to deformation and failure under mining disturbance, which seriously endangers mine safety. To reveal the influence mechanism of intermediate principal stress on its mechanical behavior, true-triaxial loading tests were conducted on floor mudstone specimens from Talahao Coal Mine in Inner Mongolia. The stress-strain evolution characteristics, strength laws, and failure modes of rock samples under different intermediate principal stress ratios (σ₂/σ₃) were analyzed. The results show that the peak strength of weakly cemented mudstone has a significant positive correlation with the intermediate principal stress ratio, and the peak strength increases by 45.43% with the rise of σ₂/σ₃. The elastic modulus increases first and then decreases with increasing σ₂/σ₃, reaching the maximum value in the range of 1.5~2.0. The regularity of fracture surfaces decreases, and the failure pattern becomes more complex as σ₂/σ₃ increases. Comparison of strength criteria indicates that the Mogi-Coulomb criterion presents the best fitting performance for the test data, with a coefficient of determination R² of 0.9793. The research results can provide a reference for deep roadway support design and parameter selection for numerical simulation in western mining areas.